marine reserves may eventually have a positive influence on adjacent fisheries. Although

evidence for spillover has increased recently, mechanisms inducing movement of adult fish

from reserve to fished areas are poorly understood. While density-dependent export is a

reasonable expectation, given that density of fish targeted by fisheries should increase over

time inside well-protected no-take reserves, no study to date has demonstrated development

of the process. This study provides evidence consistent with density-dependent export of

a planktivorous reef fish, Naso vlamingii, from a small no-take reserve (protected for 20

years) at Apo Island, Philippines. Mean density of N. vlamingii increased threefold inside

the reserve between 1983 and 2003. Density approached an asymptote inside the reserve

after 15–20 years of protection. Modal size in the reserve increased from 35 to 45 cm total

length (TL) over 20 years of protection. In addition, both density and modal size increased

outside the reserve close to (200–300 m), but not farther from (300–500 m), the reserve

boundary over the 20 years of reserve protection. Movement of adult N. vlamingii across

the boundaries of the reserve was rare. Aggressive interactions among adult N. vlamingii

were significantly higher (by 3.7 times) inside than outside the reserve. This suggests that

density-dependent interactions were more intense inside the reserve. When interacting adults

differed in size, the larger individual usually chased away the smaller one. Furthermore,

the mean size of adult fish captured by experimental fishing decreased from 35-cm TL 50–

100 m outside the boundary, to 32-cm TL 250–300 m outside the boundary. This represents

some of the best evidence available for density-dependent home-range relocation of fish

from a no-take reserve.

regions along the western to southeastern coastal area in Sri Lanka was studied using

RAPD (Random Amplified Polymorphic DNA). Intra- and interspecific variation was observed

using 20 primers of the 45 primers screened. Some primers showed diagnostic banding patterns and

allowed unambiguous differentiation between B. sexangula and B. gymnorhiza without any indication

of hybrid individuals. RAPD markers were also used to produce a similarity matrix among

individuals of a species. A higher degree of polymorphism was observed within populations of B.

gymnorhiza in Rekawa, situated in the climatically intermediate (between the wet and dry) zone,

than within populations from the wet zone (Galle and Negombo). RAPD data analysis did not reveal

a clear relationship between genetic differences and macrogeographical variation along the western

and southern coastal area in Sri Lanka, but indicated that a small population of B. sexangula was

genetically different. A more pronounced genetic difference at the population level in B. sexangula

than in B. gymnorhiza is suggested. ©2000 Elsevier Science B.V. All rights reserved.

como los ecosistemas mas productivos del planeta (Whittaker y Likens, 1975; Odum y Heald,

1975). La elevada fertilidad de los manglares y los ecosistemas lagunares-estuarinos mantiene

una rica y compleja cadena alimenticia caracterizada por una elevada produccio n. En algunos

casos, parte de esta fertilidad es exportada y contribuye con la riqueza pesquera de la zona

costera adyacente (Martusobroto y Namin, 1977). Los manglares y los complejos lagunaresestuarinos

a diferencia de los bosques templados y selvas tropicales son ecosistemas abiertos

y por lo tanto para su funcionamiento adecuado requieren del mantenimiento de los factores

externos como los aportes de agua dulce por r?os, arroyos y manto freatico, as? como una

comunicacio n al mar. Las actividades en la cuenca hidrolo gica, como en la franja litoral y zona

marina adyacente, son importantes factores de influencia en los procesos funcionales de los

manglares y lagunas costeras estuarinas. Los r?os, ecosistemas lagunares-estuarinos, los

manglares y la zona marina adyacentes estan funcionalmente vinculados a trave s de las

mareas y bocas (Fig. 18.1).

Es importante destacar que el 90% de la pesca mundial se realiza en la plataforma

continental (<200 m de profundidad) y de e sta el 70% lo constituyen organismos estuarinos o

aquellos que algu n per?odo de su vida transcurre en un ecosistema lagunar estuarino

(McHugh, 1976). El ecosistema de manglar, corresponde a la vegetacio n arbo rea de la zona

de mareas en las regiones tropicales y subtropicales. Los manglares son halo fitas facultativas

que pueden crecer a diferentes salinidades que van desde 0 ups (dulceacu?colas) hasta

hipersalinas (>40 < 80 ups), pero alcanzan su maximo desarrollo en condiciones salobres (~15

ups). Los manglares estan formados por unidades taxono micas muy diversas con mas de 50

especies agrupadas en 12 familias aproximadamente (Chapman, 1970). Es la vegetacio n

dominante que bordea las lagunas costeras y estuarios. Se estima que del 60% al 75% de las

costas de regiones tropicales estan bordeadas por manglares.

El presente cap?tulo es una revisio n del tema de los manglares, haciendo e nfasis en los

servicios, usos y funciones de los mismos y su interaccio n con la camaronicultura. As?mismo,

se discuten los impactos indirectos de la camaronicultura en los ecosistemas costeros y

finalmente se sen alan las medidas de mitigacio n en el contexto internacional y en Me xico; en

este u ltimo sentido se proponen una serie de criterios ecolo gicos con objeto de mitigar los

efectos de las actividades camaron?colas sobre los manglares y los ecosistemas lagunares

costeros.

described as occurring in the upper intertidal zone

of mangrove forests, but mature trees are occasionally

found at lower elevations. In the Utwe River basin, on the

Pacific island of Kosrae, we investigated the relative

importance of several biotic and abiotic factors that may

control the intertidal distribution of X. granatum. Factors

we evaluated included differential seed predation across

the lower, mid, and upper intertidal zones and seedling

responses to salinity, tidal flooding, and shade. Seed

predation was 22.4% over the first 34 days and varied

little among zones or in gaps versus under the forest

canopy. By day 161, there were still no differences in

seed mortality, but a significant difference was found in

seedling establishment, with much greater establishment

in the upper intertidal plots. X. granatum seedlings in a

greenhouse experiment exhibited greater growth in

freshwater than seedlings in 23 ppt salinity, which is

typical of salinity levels found in the mid intertidal zone

in our field study sites in Micronesia, where mature X.

granatum trees are generally absent. Seedlings grown in

23 ppt salinity, however, exhibited few visible signs of

stress associated with patterns in growth. Seedlings grown

in a simulated tidal flooding treatment (with 23 ppt

salinity) also showed few signs of stress. Growth declined

dramatically under 80% shade cloths, but there were few

interactions of shading with either 23 ppt salinity or

simulated tidal flooding. Differential seed predation is not

likely to be the primary factor responsible for the

intertidal distribution of X. granatum on Kosrae. However,

seedling tolerance of flooding or salinity may be more

important, especially relative to a potential contribution to

secondary stress mortality. Other factors may ultimately

prove to be more critical, such as physiological effects of

salinity on seed germination, effects of tides on seed

dispersal and rooting, or differential herbivory on

seedlings.

confluence of land and sea, have been heavily used

traditionally for food, timber, fuel and medicine, and

presently occupy about 181 000km2 of tropical and

subtropical coastline. Over the past 50 years, approximately

one-third of the world’s mangrove forests have

been lost, but most data show very variable loss rates

and there is considerable margin of error in most estimates.

Mangroves are a valuable ecological and

economic resource, being important nursery grounds

and breeding sites for birds, fish, crustaceans, shellfish,

reptiles and mammals; a renewable source of

wood; accumulation sites for sediment, contaminants,

carbon and nutrients; and offer protection against

coastal erosion. The destruction of mangroves is

usually positively related to human population

density. Major reasons for destruction are urban

development, aquaculture, mining and overexploitation

for timber, fish, crustaceans and shellfish. Over

the next 25 years, unrestricted clear felling, aquaculture,

and overexploitation of fisheries will be the

greatest threats, with lesser problems being alteration

of hydrology, pollution and global warming. Loss of

biodiversity is, and will continue to be, a severe

problem as even pristine mangroves are species-poor

compared with other tropical ecosystems. The future

is not entirely bleak. The number of rehabilitation and

restoration projects is increasing worldwide with some

countries showing increases in mangrove area. The

intensity of coastal aquaculture appears to have

levelled off in some parts of the world. Some commercial

projects and economic models indicate that

mangroves can be used as a sustainable resource,

especially for wood. The brightest note is that the rate

of population growth is projected to slow during the

next 50 years, with a gradual decline thereafter to the

end of the century. Mangrove forests will continue to

be exploited at current rates to 2025, unless they are

seen as a valuable resource to be managed on a

sustainable basis. After 2025, the future of mangroves

will depend on technological and ecological advances

in multi-species silviculture, genetics, and forestry

modelling, but the greatest hope for their future is for

a reduction in human population growth.

Keywords: mangrove forest, conservation, exploitation,

coastal resources, management, current state, projection

regions. Yet the conversion of mangrove forest, due in particular to aquaculture development, is occurring at a dramatic rate.

Drawing on insights and concepts offered by political ecology and complex systems, processes of mangrove forest conversion and

aquaculture development in the coastal zone of Banawa District, Central Sulawesi, are analyzed. This is accomplished by exploring:

(1) the comparative benefits of aquaculture developments and intact mangrove forest ecosystems; (2) a policy narrative supportive of

intensified aquaculture development at the expense of common property resource systems in the region; and (3) the manner in which

this narrative interacts with cross-scale administrative, institutional, economic, socio-cultural and property rights dynamics. The

analysis suggests that policy and management issues aimed at conserving mangrove forests and alleviating the ecological and socioeconomic

impacts of aquaculture development in the region are not simply a matter of government formulating, enforcing and

monitoring regulations that guard against mangrove forest conversion. Rather, there is a need to formulate, propose, implement and

monitor strategies that contest existing policy narratives and challenge entrenched economic interests and power relationships.

California, México were studied. The density (4700 ha) and basal area (13.5m2 ha) were more

characteristic of a fringe-type mangrove stand, while average height (2.7 m), number of species in

0.1 ha (1), and complexity index (1.7) were closer to those of a dwarf-type mangrove. Structure is

jointly influenced by a high rate of evaporation (2982 mm per year), scarce rainfall (290 mm per

year, mainly in summer) and a brief period of tidal flooding (also only in the summer). Litterfall averaged

1.75 t ha per year, placing it even lower than the lowest value reported so far for mangrove

litterfall (2–16 t ha per year). Litterfall showed a unimodal seasonal pattern, with higher values in

summer. Rainfall, sea level and the ratio rainfall/evaporation explained 86% of the seasonal litterfall

variability.

remote sensing sensors and analysis techniques for the purpose

of mangrove mapping. A study area in Southern Thailand of

approximately 40 x 30 km size was selected. A systematic

assessment of strengths and limitations of data taken from

different sensors, namely Landsat TM, Spot HRV, MOS

MESSR, JERS-1 SAR and ERS-1 SAR, was carried out. The

results of the investigation show that optical remote sensing data

is highly suitable for mapping mangrove forests and can

discriminate reasonably well four mangrove forest classes,

namely homogeneous rhizophora, homogeneous nypa, mixed

dense and mixed open mangrove forest. The classification

accuracy is approximately 87%. The use of radar data alone

resulted in a significantly lower classification accuracy, but on

the other hand provided additional information related to the age

distribution of rhizophora stands.

a variety of pollinators including birds, bats, and insects.

This study analyzed the floral scent chemistry of mangroves

on Iriomote Island (located near Taiwan) including

Bruguiera gymnorrhiza (L.) Lamk. (Rhizophoraceae),

Kandelia candel (L.) Druce (Rhizophoraceae), Rhizophora

stylosa Griff. (Rhizophoraceae), Sonneratia alba J. Smith

(Sonneratiaceae), Nypa fruticans (Thunb.) Wurmb.

(Palmae), Lumnitzera racemosa Willd. (Combretaceae),

Avicennia marina (Forsk.) Vierh. (Avicenniaceae or Verbenaceae),

and Pemphis acidula Forst. (Lythraceae). A

total of 61 chemicals (fatty acid derivatives, terpenoids,

carotenoid derivatives, benzenoids, nitrogen-containing

compounds, 13 unknown chemicals) were detected in the

floral scents of the various species. The species displayed a

distinct chemical profile ranging from only two chemicals in

the floral scent of Kandelia candel to more than 25 chemicals

in the floral scent of Nypa fruticans. All of the identified

chemicals have been found in the floral scents of other

angiosperms. The chemical profile of some species can be

correlated with their floral morphology and pollinators.

mangroves (mangroves, mangrove minors and mangal associates). It describes how people have and are using

mangroves on a traditional basis. It also describes the world’s mangrove resources and products, in terms of their

economical importance, medicinal values and other uses and functions. The economical uses of products from

mangrove ecosystems are many and varied. Traditionally, the mangroves have been exploited for firewood and

charcoal. Use has also been found for mangroves in the construction of dwellings, furniture, boats and fishing gear,

tannins for dyeing and leather production. Themangroves provide food and wide variety of traditional products and

artefacts for the mangrove dwellers. Extracts and chemicals from mangroves are used mainly in folkloric medicine

(e.g. bush medicine), as insecticides and piscicides and these practices continue to this day. However the extraction

of novel natural chemical compounds from mangroves, in addition to those already known to the pharmacopoeia

of the people is in its infancy. A knowledge of the biological activities and/or chemical constituents of plants is

desirable, not only for the discovery of new therapeutic agents, but because such information may be of value in

disclosing new sources of already known biologically active compounds. It is of further value to those interested

in “deciphering” the actual value of folkloric remedies.

and coastal fish resources. A review of the literature

highlights the lack of quanti®ed relationships. We show

that mangroves can be considered as a particular case of

an estuarine environment, and then address the broader

issue of the relationships between tropical estuaries and

®shery resources. An estuarine fish community is com-

posed of three main assemblages, respectively from con-

tinental, strictly estuarine or marine origin. The major

characteristics of these assemblages are defined. On this

basis we detail the diferent and sometimes opposite im-

pacts of major rehabilitation actions on each assemblage.

The biological approach is then widened by a critical

overview of current approaches in economic valuation of

mangrove-related fish resources. This provides a rational

and scientific foundation for economic analysis of re-

sources and for coastal management decisions, and allows

us to define priorities for further scientific and policy

research in these areas.

(USA, some states in Mexico), the systematic destruction

of these ecosystems is increasing. Deforestation of

mangrove communities is thought to be one of the major

reasons for the decline in coastal fisheries of many tropical

and subtropical countries. Although mangroves in the

tropics can regenerate themselves or be restored using

low-technology propagule planting, arid mangroves

(areas having limited or no access to fresh water) can

seldom regenerate, and if they do, it happens very

slowly. To conserve arid tropical mangrove ecosystems,

maintenance and restoration of the microbial communities

is required. There is sufficient published evidence to

propose a close microbe–nutrient–plant relationship that

functions as a major mechanism for recycling and conserving

essential nutrients in the mangrove ecosystem.

The highly productive and diverse microbial community

living in tropical and subtropical mangrove ecosystems

continuously transforms dead vegetation into sources of

nitrogen, phosphorus, and other nutrients that can later

be used by the plants. In turn, plant-root exudates serve

as a food source for the microorganisms living in the

ecosystem, with other plant material serving a similar

role for larger organisms, such as crabs and detritusfeeding

fish. This speculative synthesis of recent work

on growth-promoting bacteria proposes that mangrove

rhizosphere bacteria be used as a tool to enhance reforestation

with mangrove seedlings. This can be done by

inoculating seedlings with plant-growth-promoting bacteria

participating in one or more of the microbial cycles

of the ecosystem.

swamp-forest litter, seagrasses, seagrass epiphytes, and marine particulate organic

matter [MPOM]) from four estuaries on Kosrae, Federated States of Micronesia for stable

isotope (d13C and d34S) analysis. Unique mixing solutions cannot be calculated in a dualisotope,

five-endmember scenario, so we tested IsoSource, a recently developed statistical

procedure that calculates ranges in source contributions (i.e., minimum and maximum

possible). Relatively high minimum contributions indicate significant sources, while low

maxima indicate otherwise. Litter from the two forest types was isotopically distinguishable

but had low average minimum contributions (0–8% for mangrove litter and 0% for swampforest

litter among estuaries). Minimum contribution of MPOM was also low, averaging

0–13% among estuaries. Instead, local marine sources dominated contributions to consumers.

Minimum contributions of seagrasses averaged 8–47% among estuaries (range 0–88%

among species). Minimum contributions of seagrass epiphytes averaged 5–27% among

estuaries (range 0–69% among species). IsoSource enabled inclusion of five organic matter

sources in our dual-isotope analysis, ranking trophic importance as follows: seagrasses .

seagrass epiphytes . MPOM . mangrove forest . freshwater swamp-forest. IsoSource is

thus a useful step toward understanding which of multiple organic matter sources support

food webs; more detailed work is necessary to identify unique solutions.

programa regional plurianual de cooperación

en el campo de pesca entre los seis países centroamericanos

Guatemala, Honduras, El

Salvador, Nicaragua, Costa Rica y Panamá y la

Unión Europea iniciado en 1990. Uno de los

últimos eventos públicos organizados por PRADEPESCA

fué un taller regional sobre el tema

Monitoreo y manejo de áreas costeras con énfasis en

la camaronicultura, que tuvo lugar en Managua

(Nicaragua) en los días 26-28 de mayo de 1999.

El taller era enfocado al desarrollo de las áreas

costeras del Golfo de Fonseca compartido entre

Nicaragua, Honduras y El Salvador.

La gran actualidad del tema resultó de la nueva

situación del cultivo de los camarones peneidos

en el Istmo Centroamericano. En Honduras,

Nicaragua y El Salvador existen alrededor de

20,000 ha de cultivos de camarones, convirtiendo

el Istmo en el segundo lugar de mayor producción

en Latinoamérica. En Nicaragua este cultivo

empezó a lograr éxito económico relativamente

tarde, alcanzando niveles importantes en el año

1994 (1,076.5 t) y triplicándose este resultado

hasta 1997 (3,165.1 t). Sin embargo, ya en el año

1998 las expectativas de casi 5 mil t se frustraron

a causa del huracán Mitch que redujo la producción

esperada en un 20% es decir que solamente

se produjeron 4,068.5 t. Por añadidura, desde

enero de 1999 la camaronicultura centroamericana

se vió frente a un reto aún más grande – lo del

virus de la enfermedad llamada mancha blanca

que amenaza la industria camaronera de manera

muy seria. Había entonces que reconsiderar a

fondo los conceptos y procedimientos de esta

industria, inclusive los aspectos higiénicos.

El fuerte desarrollo de la camaronicultura y las

perspectivas económicas de esta industria relegaron

al segundo plano las preocupaciones por la

protección de los manglares. Si bien es verdad

que se establecieron reglamentos, p.ej. relativo a

“franjas de amortiguamiento”, su observancia es

precaria – en perjuicio de las mismas granjas

camaroneras. Con la aparición de la mancha blanca

la situación podría cambiarse debido a la tendencia

en el uso de un sistema de ciclo cerrado con

cultivo intensivo en lugar de expandir las áreas.

El rápido desarrollo de la camaronicultura en los

últimos años y los reveses sobrevenidos atraen la

atención a las estrechas interconexiones entre

ecología costera y protección de los manglares,

desarrollo de la camaronicultura y manejo de las

áreas costeras. El desarrollo de la camaronicultura

en áreas de manglares requiere de una mejor

comprensión de la ecología de las áreas costeras.

Los efectos ecológicos, económicos y sociales de

este desarrollo destacan la necesidad de una

vista integral sobre los nuevos acontecimientos.

intact mangrove forest left on mainland Singapore. Mangroves colonized the area around

6820 BP, as sea level rose following the last glacial maximum and a variable thickness of

Holocene sands, muds and peats (generally ~1 to >3.8 m thick) were deposited over the pretransgression

land surface.

An analysis of a time series of photographs covering the period from 1946 to 2001 has

revealed major changes in the distribution of mangroves in the area resulting from development-

induced changes in the local hydrodynamic regime and clearance for aquaculture.

Mangroves covered 117.3 ha in the study area in 1946 and were actively advancing over the

coastal mudflats until 1980. Despite the addition of 6.24 ha from mangrove colonization, the

total area covered by mangroves was reduced by ~50% by 1980 due to clearance for aquaculture.

Following 1980, a reduction in sediment supply possibly due to the construction of

the Kranji Dam, immediately east of the study area, led to the initiation of erosion along

much of the coastline, with the mangrove fringe having retreated by up to 50 m in 2001.

Establishment of the wetland reserve in 1992 enabled the partial regeneration of mangroves

in the area to 86.8 ha, 25% less than in 1946.

Three areas of undisturbed old growth mangroves >55 years in age have been identified

and are considered to be of high conservation value. Two of these areas are within the current

boundaries of the Sungei Buloh Wetland Reserve, but are located along coastal areas

that are undergoing severe erosion. The third area is located in the south of the study area,

protected from coastal erosion, but outside the current nature reserve boundary and hence is susceptible to loss as a result of future development. This third area is possibly the oldest

undisturbed fragment of mangrove forest on mainland Singapore.

strong disturbances have occurred.We surveyed 31 mangrove localities in Buenaventura Bay, Central Pacific Coast

of Colombia, where structural parameters were measured within a 0.1 ha plot. Also, most likely disturbances were

noted for each plot. Complexity index was calculated in its classical form using the arithmetic mean of the three

tallest trees (maximal mean) and alternatively using: a) the total mean: the height average of all trees recorded in

each plot; and b) the mode: the most frequent tree height class (10 cm intervals) within each plot. Afterwards,

we compared the three computations and discussed the reliability of each one according to the current state by

plot. In addition, all structural parameters were sorted in two diameter at breast height (dbh) cohorts (2.5–10 cm

and >-10 cm) to figure out which contributes more to the forest structure. We conclude the following: (a) The

mean of the three tallest trees is not a good estimator of forest development when seasonal or strong disturbances

occur since complexity index based in it always overestimates forest structure. (b) Seasonal disturbances and

recruitment produce mosaic forests. The best estimator of this condition is the mean height which encompasses

both central tendency and variability. (c) The modal height is also helpful to establish the dominant cohort when

forests show two or more storied-canopies, or intermediate cohorts are missing. It also applies when a new stock

of recruits is entering in a mature forest (the modal or maximal heights can be used interchangeably in this case).

(d) Maximal height is the best estimator for uniformly developed forests with closed canopies and/or a single

dominant tall-cohort. (e) If one is not confident about which height type to include to compute the complexity

index, we recommend to sort out structure data by dbh-cohorts and calculate indices for both of them. This will

show which cohort is contributing most to forest complexity. Finally, we suggest to exclude non-mangrove species

from the complexity index computation since they mostly do not contribute significantly to forest basal area.

nutrient dynamics in previously deforested plantations. Dynamics of nutrients (carbon, nitrogen and C:N ratios) in decomposing

leaves of conspecific species were investigated with litterbags in Sonneratia alba and Rhizophora mucronata reforested treatments

using appropriate bare and natural less disturbed treatments as controls. Bare treatments had the lowest decay rates (Kd -1) and

thus the highest t50 values (when 50% of the original weight had been decomposed) for both species. The contrary was true for

natural treatments, while both parameters were intermediate in reforested treatments, suggesting that other than direct litter input,

reforestation has modified site conditions which have enhanced organic matter decomposition. There were significant seasonal

differences in decay rates for treatments within the R. mucronata species, with rates being higher during the wet season with accompanying

lower t50 values. Decay rates were overall higher (P < 0.05) in the S. alba species and as a result no litter was retrieved from

its natural treatment by the 5th week. Higher amphipod colonisation was observed in reforested and natural treatments than bare

treatments, which may have contributed to higher decay rates in the former. There were significant differences (P < 0.05) in N

concentration among treatments with natural and reforested treatments having similarly higher concentrations than bare treatments

in both seasons. C:N ratios (an important determinant of nutritional leaf quality) were also similarly low in natural and reforested

treatments and higher in bare treatments. Mangrove reforestation thus seems to have enhanced litter degradation and concomitant

nutrient remineralisation, suggesting that other than species litter quality, tidal inundation and seasonal factors, specific stand

management regimes play an important role in determining the efficiency of these ecological processes in mangrove ecosystems.

Although some would appear to be sedentary, all are capable of invading new territory at some stage in

their life cycle. Underlying these comparatively rapid changes is a much slower evolutionary system

whereby new species are formed and spread out. Depending on their place of origin and genetic

resources, some of the new species may give rise to continuing phyletic lines. At the same pace, some

older species approach extinction by continuing to lose territory. Over time, this evolutionary system

appears to be no less dynamic than the contemporary one.

In recent years, considerable attention has been paid to the East Indies as a centre of origin for the

marine tropics. While other centres of origin in the Antarctic and the North Pacific have been

recognized, little attention has been paid to their external influence. Yet in the cooler waters of the

oceans, they are as important to those areas as the East Indies is for the tropics. Evidence indicates that

evolutionary flows from all three centres contribute to a dynamic system that extends throughout the

world ocean. Each of the three centres and its salient features is discussed in turn, the information is

summarized, and then stated in the form of a hypothesis.

a number of riverine estuaries along the eastern coast of Cape York Peninsula, in the Gulf of Carpentaria and at one

location in Van Diemen Gulf in the Northern Territory. Detailed records were taken of species occurrences along

shore normal transects upstream to tidal limits in each system. A simple numeric procedure developed by Williams,

Bunt and Clay (Marine Ecology Progress Series 72: 283±287, 1991) was applied to the data to de®ne species sequential

ordering across the intertidal surfaces. Considerable diversity in zonal pattern was found, partly the result of ¯oristic

differences between and along rivers within the study area but also arising from variability in the centres of

distribution of species across the intertidal surface. Close examination of the data suggests the variability to be

attributable to the differing responses of individual species to the character and pattern of environmental controls

operating from point to point locally and at larger scales throughout the mangrove environment. It is concluded that

constancy of centres of distribution and of sequencing order under conditions in tropical Australia are not to be

expected. At the same time, within the range of along transect species distributions, conditions are likely to be

encountered which permit individual species, whether rarely or not, to occupy all or most of the intertidal surface.

Any other pattern of distribution is interpreted to represent conditions which, at least to a degree, are limiting for the

species in question. In mangrove environments of considerable diversity, only extensive survey can be expected to

reveal the full extent of zonal pattern in the associated vegetation.

biocénoses marines de la baie du Grand Cul-de-Sac Marin a été réalisé. Dans les Antilles, ces biocénoses sont souvent

intriquées de façon complexe, ce qui rend leur cartographie difficile. Les techniques de télédétection spatiale et

aéroportée peuvent apporter des solutions à ce problème. Dans le présent travail, une méthode d’analyse des données XS

du satellite SPOT a été mise au point pour améliorer nettement la discrimination des objets, même profonds, en

amplifiant des différences spectrales minimes associées à un signal de très faible intensité. Des surfaces de référence sont

délimitées en vue de construire une classification supervisée ; 32 thèmes sont identifiés sur une superficie de 23 700 ha,

jusqu’à l’isobathe 20 m. La mangrove occupe 2 700 ha et les surfaces immergées incluent 3 800 ha de fonds durs et

15 700 ha de fonds meubles. Sur les récifs, les communautés coralliennes florissantes ne représentent que 113 ha, soit

11,2% de la surface des récifs cartographiés. Ce résultat met en évidence l’état alarmant des récifs coralliens en

Guadeloupe. Sur les fonds sédimentaires, une attention spéciale est accordée aux herbiers de phanérogames marines qui

constituent un faciès particulier occupant 8 200 ha, soit 42% des biocénoses infralittorales cartographiées et 58% des

fonds meubles. Leur description fait l’objet de 12 thèmes, différenciés sur la base du taux de recouvrement des fonds par

les phanérogames et du type de sédiment colonisé par ces plantes. La méthode d’inventaire cartographique (analyse de

données SPOT) révèle la grande complexité de la zone d’étude. La carte produite constitue un outil de référence à la

disposition des scientifiques et des gestionnaires de cet espace. © 2001 Ifremer/CNRS/IRD/Éditions scientifiques et

médicales Elsevier SAS.

to understand the general pattern of optimum forest stature at the mouth of estuaries in the Everglades, such as the

Shark River Slough, Florida (U.S.). The basal area of mangroves decreases from 40.4 m2 ha21 and 39.7 m2 ha21 at two

stations 1.8 km and 4.1 km from the estuary mouth to 20.7 m2 ha21 and 19.6 m2 ha21 at two sites 9.9 km and 18.2 km

from the mouth, respectively. The gradient in basal area at these four sites is mostly the result of approximately 34 yr

of growth since Hurricane Donna. Wood productivity is higher in the lower estuary (10.7 Mg ha21 yr21 and 12.0 Mg ha21

yr21) than in the upper estuary (3.2 Mg ha21 yr21 and 4.2 Mg ha21 yr21). Porewater salinity among these four mangrove

sites during seasonal sampling in 1994 and 1995 ranged from 1.6 g kg21 to 33.5 g kg21, while sulfide was generally ,

0.15 mM at all sites. These soil values indicate that abiotic stress cannot explain the decrease in forest structure along

this estuarine gradient. Concentrations of nitrogen (N) and phosphorus (P) are more closely related to patterns of forest

development, with higher soil fertility at the mouth of the estuary as indicated by higher concentrations of extractable

ammonium, total soil P, and available P, along with higher ammonium production rates. The more fertile sites of the

lower estuary are dominated by Laguncularia racemosa, whereas the less fertile sites in the intermediate and upper estuary

are dominated by Rhizophora mangle. Relative N mineralization per unit of total N is higher in the lower estuary and is

related positively to concentrations of available P, indicating the importance of turnover rates and nutrient interactions

to soil fertility. Concentrations of Ca-bound P per volume soil in the lower estuary is 40-fold higher than in the upper

estuary, and along with an increase in residual P in the upper estuary, indicate a shift from mineral to organic P along

the estuarine gradient. Mineral inputs to the mouth of Shark River estuary from the Gulf of Mexico (rather than upland

inputs) apparently control the patterns of mangrove structure and productivity.

Propagule (diaspore) predation by crabs has been shown to be a major source of

mortality for mangroves. We measured predation by crabs on seeds of nine tropical

mangrove species in multifactorial experiments by following the fates of tethered

propagules.

2

We tested whether planting, intertidal position and canopy gaps influenced predation

of propagules and whether the predation of propagules was reduced in the presence of

conspecifics. We also tested if predation influenced patterns of propagule establishment.

3

Mortality due to predation ranged from 22 to 100%, with

Aegiceras corniculatum > Avicennia marina > Bruguiera parviflora > Aegialitis annulata

> B. exaristata > Ceriops australis > C. decandra = B. gymnorrhiza > Rhizophora stylosa

. Initial predator preference

was correlated with the size of propagules.

4

Propagule planting (prone vs. implanted) and canopy type had the largest magnitude

of effects across all species for treatment effects. Propagules dispersed in the prone

position had more mortality while those dispersed into canopy gaps were generally

less preyed upon. Three species were tested for dominance-predation by regression of

stand relative density with final predation by crabs for canopy treatments. No species

had significant effects that supported the hypothesis.

5

Predation by crabs often changed with intertidal position but showed no consistent

pattern among species or gap treatments. Interactions of canopy treatment and tidal

position showed that predation by crabs did not have a major influence on the zonation

of mangroves in our study sites.

6

Analyses of covariance of predation and establishment showed that establishment

success is strongly controlled by predation in six of the nine species tested. This suggests

that herbivores have a greater impact on recruitment than do microhabitat effects on

resources. The combined effects of predator refuge and growth preference enhance

recruitment in large canopy gaps. Crab predators appear to maintain the floristic

similarity between canopy gaps and surrounding forests in tropical mangrove forests of

northern Australia by removing allopatric species from gaps.

mangrove forest in North Brazil is discussed in relation to existing phosphate and physicochemical data in waters

of an adjacent tidal creek. Due to smooth topography, an increase of 20 cm in tidal height above average neap tides

increases flooded area from about 50 to 80%. Analysis of the relationship between microtopography, tidal height

and flooding rate showed that in the upper 60 cm of the mangrove forest, increases of 20 cm in topographical

height resulted in a doubling of the inundation frequency. This can be particularly relevant for the analysis of

nutrient mobilization and vegetation structure of infrequently inundated wetlands. Throughout the year, low-tide

phosphate in creek water was inversely proportional to the maximum area flooded during high tide, this correlation

being higher during the dry season. Similarly, the inverse relationship between flooded areas and low-tide / hightide

pH ratios was highly significant during the dry season and the beginning of the rainy season. Although the

high correlations obtained are based on data pairs obtained at high and low tide, it has to clarified whether the

association between inundation degree and creek water pH is relevant for the stability of P compounds in sediment

on the short scale of a tidal cycle.

Taylor River Slough in the Everglades National Park, were studied. Although the four mangrove species reported

for Florida occurred at the study site, dwarf Rhizophora mangle trees dominated the forest. The structural

characteristics of the mangrove forest were relatively simple: tree height varied from 0.9 to 1.2 meters, and tree

21 density ranged from 7062 to 23 778 stems ha . An allometric relationship was developed to estimate leaf, branch,

prop root, and total aboveground biomass of dwarf Rhizophora mangle trees. Total aboveground biomass and their

components were best estimated as a power function of the crown area times number of prop roots as an

20.5083 independent variable (Y5 B 3 X ). The allometric equation for each tree component was highly significant

2 (p,0.0001), with all r values greater than 0.90. The allometric relationship was used to estimate total

21 aboveground biomass that ranged from 7.9 to 23.2 ton ha . Rhizophora mangle contributed 85% of total standing

crop biomass. Conocarpus erectus, Laguncularia racemosa, and Avicennia germinans contributed the remaining

biomass. Average aboveground biomass allocation was 69% for prop roots, 25% for stem and branches, and 6%

for leaves. This aboveground biomass partitioning pattern, which gives a major role to prop roots that have the

potential to produce an extensive root system, may be an important biological strategy in response to low

phosphorus availability and relatively reduced soils that characterize mangrove forests in South Florida.

most of the main islands of the Hawaiian Archipelago. We investigated the structural properties .and estimated productivity

of a R mangle population at Nuupia Ponds Wildlife Management Area (NPWMA), on windward Oahu, where the

mangroves were being controlled due to their propensity to overgrow archaeological sites and the habitat of endangered

Hawaiian waterbiids. Mangroves within NPWMA were very dense (> 24,000 trees ha-‘) and most were relatively small

(only 3.3% of the trees were 2 10 cm DBH). Mean basal area, aboveground biomaq’and number of seedlings were all

high, at 37.2 m* ha-t, 279 t (dry wt) ha-‘, and 121 m-*, respectively. The seedlhtg density may be particularly unusual

and appears to be due to extremely high rates of propagule production coupled with low rates of propagule predation.

Stand productivity was estimated by stem growth (allometry), litterfall, and a light attenuation approach to determining

net canopy photosynthetic production. All three methods yielded estimates that are higher than previously reported for

R. mangle and comparable with estimates of highly productive Rhiwphura sppdominated stands in Australia and Asia.

The high density, biomass, and productivity of this stand relative to stands within the species’ native range may be due

to a combination of favorable site conditions, lack of competition from other woody plants, and very low rates of

herbivory and propagule predation.

satellite imagery with a very high spatial resolution of 1 metre to distinguish two

mangrove species in Sri Lanka belonging to the same genus (Rhizophora apiculata

and R. mucronata). Not only is this an advancement for the monitoring of forests,

it is even more important considering their patchy nature in Sri Lankan mangroves

(in contrast to classically zoned forests). Apart from congeneric distinction, introgressive

species (Acrostichum aureum) can also be detected from IKONOS imagery,

which is important in the early warning for cryptic ecological changes that may affect

mangrove species composition (both floral and faunal) and functioning. The

results tabulate the usage of various image composites, transformations and classifications,

and indicate the danger of too much detail in remote sensing, and the

need to apply an optimum resolution. We also highlight that the highest resolutions

(as in pansharpened multispectral composites) remain invaluable for visual ecological

investigations, which are not at all outdated by new digital satellite images of

(sub)metre spatial resolution and their possibility for computer-aided analysis.

a quantitative and qualitative evaluation of the degradation of vegetation structure and dynamics of

mangrove communities over a period of 25 yr, using aerial photography in a geographical information

system (GIS), combined with ground-truth data for different vegetation layers, and with faunal

and environmental factors. Retrospective analysis and understanding of current practices were aided

by interviews with Gazi village elders and by field observations of mangrove tree stumps. GIS-based

vegetation maps were combined with data obtained using the point-centred quarter method

(PCQM), an accuracy analysis was performed, and forestry parameters were derived from the resultant

PCQM data. In addition to general human-induced degradation of vegetation structure and

floristic composition of the seaward mangrove zone, a particular sandy beach is expanding at the

expense of mangrove, whereas the back mangrove zone has undergone minor changes. Aerial

photographs of 1992 and current field data show an apparent zonation of 6 different monospecific or

mixed mangrove communities, with a high importance of Rhizophora mucronata in each community

and each vegetation layer. Retrospective vegetation structure was combined with correspondence

analyses on the PCQM data derived for adult, young and juvenile trees in order to make predictions.

Present dynamics initiated by anthropogenic degradation of mangroves continues, even though

human impact has diminished. We predict that under a ‘no impact scenario’, the sandy ridge will

continue to expand, that this will speed up under a ‘mangrove cutting scenario’, and that a scenario

altering the complex topography will lead to a major re-organisation of the mangrove and terrestrial

vegetation structure.

the field for three vegetation layers: adult trees, young trees, and juvenile trees. A minimum of 25 sample points,

in which the vegetation was described and environmental factors (salinity, light intensity, land/water ratio, abundance

of herbivorous crabs and snail abundance) were measured or estimated, were taken on each site. Detrended

correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to summarize the data

bulk, to investigate the vegetation dynamics (e.g., comparability of species distribution in the three vegetation

layers), and/or to link the vegetation data to the environmental factors. Results showed that species clusters were

relatively easy to delineate, whether mangrove zonation was present or not. Among the environmental factors,

the abundance of propagule predators (mostly sesarmid crabs) contributed significantly to the variation in vegetation

and could be an explanatory parameter for the observed vegetation data in a majority of sites. In the site

where it was not, the most important factor in the ordination was the land/water ratio, which is important at the

ecological level as well (link between water level and vegetation dynamics). However, none of the environmental

factors could successfully explain the total variability in the vegetation data suggesting that other, more determining

factors exist. Our results further provide information on the dynamic or non-dynamic nature of a forest

and on its ability to rejuvenate, and may contribute to appropriate forestry management guidelines in the future.

settings in the application of the PCQM are amongst others due to the presence of multiple-stemmed trees (MST), to ambiguous settings for

measuring the sampling point to nearest tree distance or the tree diameter, both of which may result in erroneous estimation of silvimetric variables

and parameters. The analysis is based on a database of effective individual tree records including distances, diameters, and heights measured in the

field in a Sri Lankan mangrove forest between 1997 and 2002, and randomly compiles a series of records that were used as PCQM sampling points.

Various structural forest parameters were calculated, with particular emphasis on density and basal area.

After proving that multiple- and single-stemmed trees have different silvimetric characteristics, we adopted an empirical approach to

demonstrate the classical PCQM protocol applied to MST generates significantly different densities (overestimation) and basal areas (underestimation)

depending on which stems are considered for measurement, and we suggest an adapted PCQM+ protocol (measurement of central stem

instead of nearest stem). We test both protocols in two mangrove assemblages (one composed of Excoecaria agallocha only, and an Excoecaria

agallocha/Rhizophora apiculata mixed forest) with MST proportions varying between 0% and 100%, at 5% intervals.

The results indicated that the classical PCQM protocol generates density and basal area results that are strongly correlated with the MST

proportion in the assemblage ( p < 0.001), whereas the PCQM+ protocol shows a robustness with no such correlations for density. For basal area

the results of the PCQM+ protocol showed a weak correlation with the MST proportion, and regression-ANCOVA results indicated that they were

significantly different from those of the highly sensitive PCQM protocol ( p < 0.001).

Finally, we conclude by writing out the entire PCQM+ protocol, elaborating on the solutions to other common problems related to ambiguous

settings for the consideration of stems or the measurement of their diameter (aerial roots, split trunks, dwarf growth, horizontally developing stems,

boundary of an individual in MST, selectively cut trees or tree parts, very sparse assemblages, use of PCQM for remote sensing ground-truth), and

by nevertheless highlighting the potential of the PCQM/PCQM+ approach. Although we used a mangrove forest data set, the PCQ-Method and our

suggestions are widely applicable to other forest types. In addition, this paper is accompanied by the first interface that automatically processes

standard PCQM-related data (regardless of forest type) to generate common silvimetric or forestry parameters elaborated in this paper, and it is

freely available in Appendix C and from http://www.vub.ac.be/APNA/staff/FDG/pub/pub.html.

and functioning of such systems is fully appreciated, particularly with regard to small-scale studies. The

present study provides some new data on the interaction between mangroves and crabs, namely the link between

the distribution of particular mangrove tree species and the distribution of certain crab species at the assemblage

level. Floristic and faunistic relevés were made in Gazi Bay (2 sites) and Mida Creek (3 sites), 140 km apart on the

Kenyan coast, along five transects in a series of quadrats covering the width of themangrove belts. Zonation of both

mangrove vegetation and brachyuran fauna was described and height above datum and distance to the mainland

(limit of non-flooded area) measured. The relationship between the presence and the absence of crabs and trees

was analysed using detrended correspondence analysis.

Summarized, the mangrove tree zonation pattern contains four assemblages with a particular dominant species:

first a landward Avicennia marina zone, followed by a mixed zone with Ceriops tagal, Rhizophora mucronata and

Bruguiera gymnorrhiza, and finally a R. mucronata zone and a Sonneratia alba zone, both of which can mix with

seaward A. marina. Ordination results show that the distribution of Neosarmatium meinerti and Sesarma ortmanni

is linked to the landward A. marina zone, that of Neosarmatium smithii, Sesarma guttatum and Sesarma leptosoma

corresponds to the R. mucronata zone and that of Metopograpsus thukuhar and Sesarma elongatum to the seaward

A. marina and S. alba zone. There appears to be one major underlying factor in the zonation of both crabs and

trees, with most likely a complex multiple causality. In certain cases the association between crabs and trees are

causal, whereas in other cases it can be the result of an independent restriction to the same zones by a common

cause.

along the Kenyan coast as a landward and a seaward zone, has been studied on

a morphological level and complemented with preliminary genetic data. The objective

was to describe the two zones in-depth in order to provide a background ecological setting

that may be used in explanations on the emergence of such a bimodal zonation. The

vegetation structure in the two zones is described by means of the Braun-Blanquet relevé

and PCQ-methods, root- and leaf-morphological characteristics, and environmental

variables to provide a background ecological setting. The two zones show considerable

differences in physiognomy of A. marina trees, and indicate that the differences may

constitute an environmental response. Results show that in the landward A. marina

zone, tree heights, leaf sizes, density, and total length of pneumatophores tend to be

smaller as compared to the same attributes of the trees in the seaward zone. Differences

in leaf stomatal density and in above- and below-ground pneumatophore length, the

latter closely related to the effect of inundation, were observed. This suggests a considerable

adaptability and plasticity with respect to environmental conditions. The hypothesis

for the genetic analysis was that mangrove fringes as close as 105 m from one

another constitute a same genetic pool. Preliminary genetic analysis using 48 amplified

DNA fragments (RAPD - Randomly Amplified Polymorphic DNA) from 37 landward

and seaward trees revealed significantly different frequencies for four DNA fragments,

indicating that there might be less contact and genetic interchange between the two

zones than within each zone. Whether this phenomenon, coupled to the different environmental

conditions, can lead to further divergence cannot be answered yet.

Ocean tsunami was almost unprecedented.

In areas with the maximum tsunami intensity,

little could have prevented catastrophic coastal

destruction. Further away, however, areas

with coastal tree vegetation were markedly

less damaged than areas without. Mangrove

forests are the most important coastal tree

vegetation in the area and are one of the

world_s most threatened tropical ecosystems.

forests on the west coast of Florida. The mean number of trees and basal area were 5040 trees ha?1 and

20.5 m2 ha?1, respectively. Basal areas ranged from 1.1 (Avicennia germinans (L.) Stern), to 2.6 m2 ha?1 (Laguncularia

racemosa Gaertner), to 16.8 (R. mangle). Cockroach Bay mangroves are small (5.8–7.0 m tall) versus

coastal forests of south Florida and the Caribbean. Total litter production for a 12 month period was maximal

in September for fringing (7.4 g d wt m?2d?1) and interior (8.7 g d wt m?2 d?1) areas with the two zones not

being significantly different. Average litter fall (3.1 g d wt m?2 d?1) was similar to more tropical Caribbean

mangals. Leaves accounted for 68% of the litter and reproductive material for 6%, being similar to tropical riverine

and overwash marine angiosperm communities on the Mexican coast. Although mangrove forests in Tampa Bay

are small in stature and experience cold damage and occasional frosts, their litter fall is similar in biomass to

that of more tropical mangals. However, their reproductive output is low based on litter fall versus more tropical

mangals suggesting that the northern extension is less than optimum. Macroalgal diversity was low (10 species) as

compared to Caribbean mangals. Macroalgal turf (0.8 g C m?2 d?1) and epiphyte communities of A. germinans

pneumatophores (2.7 g C m?2 d?1) have productivity levels that are equal to or greater than those of Caribbean

mangals.

bicolor of the Pacific coast of Costa Rica. The models were based on an extensive data set collected during a 6 year

period in a 0.52 ha plot of monospecific A. bicolor. This data set included density, growth, mortality and transition

rates of seedlings, saplings and trees of eight different diameter classes, as well as propagule production for the

reproductive tree classes. Model simulations carried out over a 100 year period indicated a stable size class structure

of the forest. Sensitivity analysis showed a significantly greater sensitivity of the model population to simulated

changes in the mortality of seedlings, in comparison with the mortality of saplings and trees. An increase of 1%

in the mortality of seedlings, for example, was sufficient to cause significant changes in the density of individual

size classes. In contrast, neither a 10% increase in the mortality of saplings and trees nor a 20% decrease in the

propagule production of fecund trees significantly affected the overall forest structure.

oceans, contains a total amount of carbon similar to atmospheric carbon dioxide. To

understand global biogeochemical cycles, it is crucial to quantify the sources of marine

dissolved organic carbon (DOC). We investigated the impact of mangroves, the dominant

intertidal vegetation of the tropics, on marine DOC inventories. Stable carbon isotopes

and proton nuclear magnetic resonance spectroscopy showed that mangroves are the main

source of terrigenous DOC in the open ocean off northern Brazil. Sunlight efficiently

destroyed aromatic molecules during transport offshore, removing about one third of

mangrove-derived DOC. The remainder was refractory and may thus be distributed over

the oceans. On a global scale, we estimate that mangroves account for >10% of the

terrestrially derived, refractory DOC transported to the ocean, while they cover only

<0.1% of the continents’ surface.

architecture of mangrove species are reviewed and

the consequences of this genetic architecture for species

response to environmental change are inferred. The origins

of mangrove taxa have been discussed many times,

particularly in the context of centers of origin and continental

drift. While global patterns of mangrove species

diversity have been interpreted in the context of tectonic

events and opening and closing of seawater passages,

species evolution on a finer scale depends on more recent

processes of population extinction and advances in

response to spatio-temporal climatic and environmental

flux. Understanding the likely effects of global climate

change on mangrove distributions requires a focus on

these more recent intraspecific evolutionary processes.

Many mangrove taxa have wide geographic ranges that

have been attributed to efficient propagule dispersal.

Such gene flow should provide a genetic cohesiveness

among populations. However, as with many wide-ranging

marine organisms, we are finding important population

genetic structure in widespread mangrove species,

suggesting that gene flow is less effective than previously

thought. Are these widespread taxa more recent and

undergoing speciation? Spatial patterns in genetically

adaptive traits indicate that some populations may survive

more successfully under changing environmental

conditions. However, is the present-day genetic architecture

best poised to respond to predictions of climate

change? These questions are addressed in the light of our

increasing knowledge of genetic diversity in mangrove

species.

to morphological analyses, which have indicated a high degree of homogeneity. However, our analyses of the aliphatic hydrocarbon and triterpenoid

fraction of foliar waxes (by gas chromatography and mass spectroscopy) of mangrove species (Khi.vphortr nznngle. Avicrnnicr germiruw and

Lagunculuriu r-ucrmow) from Gabon in West Africa and French Guiana in South America show significant genetic differentiation between eastern

and western Atlantic provenances. The greater diversity in lipid composition, and the tendency for longer carbon chain lengths in all taxa from

Africa, may suggest that American mangroves exhibit derived characteristics. A consequence of this hypothesis would be that Atlantic mangroves

are unlikely to have dispersed from the Tethys via the Pacific, as has been proposed by some authors. More widespread sampling within the Atlantic

and east Pacific region is needed to support and confirm these results.

the driest mangrove habitats in the world, in which salt concentrations may reach levels that are

beyond the physiological limit for other species. These ecosystems are poorly known, in particular,

what levels of productivity can be attained and whether there are any indications of genetic

adaptation to these exceptionally severe conditions. We have estimated standing biomass as varying

between 70 and 110 t haÿ1 for the tallest stands and between 14 and 65 t haÿ1 for shortest stands.

Our estimates for litterfall are 7.4±8.5 t haÿ1 yrÿ1 in the tallest stands and 5.1±6.9 t haÿ1 yrÿ1 in the

shortest stands. These values of biomass are intermediate between levels reported for the same

species in New Zealand and in Australia and the estimate of litterfall is comparable with that

obtained from stands in Australia. Thus, despite the harsh ecological conditions, A. marina forms

highly productive stands. We have analyzed leaf cuticular hydrocarbon composition, by gas

chromatography, as a marker of population differentiation. The dominant alkanes were C33 and C31,

which are unusually long as compared with the other widespread species Avicennia. germinans.

Since longer carbon chain lengths appear to offer an adaptation to minimize cuticular water loss, it

would appear that A. marina has evolved under more arid conditions than A. germinans. Our

sampled population from the Inner Gulf differed in quantitative cuticular wax composition from the

Outer Gulf population, suggesting a possible genetic differentiation between the two populations.

Our data indicate the need for more detailed analyses of the possible role of genetic adaptation in

the productivity of mangrove ecosystems at the margins of their ecological range.

mangle. Twelve populations in Mexico were studied: five from the Gulf of Mexico and the Caribbean Sea, and seven from

the Pacific Coast. Six metric floral attributes were measured from a sample of 1370 flowers. Significant differences among

populations were found for all six attributes. Because floral attributes were all correlated, scores derived from principal

factor analysis were used to describe the variation in flower morphology. Two factors explained essentially all of the variance

in flower morphology. Corolla and calyx size had a strong effect on factor 1, while gynoecium size had the higher effect

on factor 2. Nested analyses of variance on the scores from both factors revealed significant differences among coasts,

among populations within coasts, and among plants within populations. Nonetheless, this variation cannot be explained as

a result of clinal variation, as indicated by a series of regression analyses. Cluster analysis (UPGMA) showed that a

population from the Pacific coast was clustered together with those of the Atlantic, and the arrangement of populations

within each coast showed no evident geographical pattern. We propose that frequent events of extinction and recolonization

by a few individuals, followed by selfing, may produce differentiation among populations of red mangrove.

influencing tree death and replacement at various temporal and spatial scales. Development in terrestrial forests

appears comparable with that in mangroves but turnover seems to differ considerably between these broad forest

types. The most important difference is in the character of small forest gaps. Gaps are common in terrestrial

forests but those in mangroves rarely involve falls of large older trees in the first instance. Instead, mangrove

trees usually die standing in small clusters of mixed age cohorts. Identifying a common cause for gap creation in

mangroves might be important towards understanding what drives forest turnover but there is a greater need to

quantify this process. Small-scale disturbance in mangrove forests is poorly quantified but preliminary evidence

implies that its’ importance may have been greatly under-estimated. Based on available observations, a conceptual

model of mangrove forest development and gap regeneration is proposed. The model helps explain the peculiar

characteristics and structure of mangrove forests and how these forests might respond to changing environmental

conditions and disturbance at various landscape scales.

plants with common features and common origins based

mostly on their broad distributional patterns, together

with an erroneous view of comparable abilities in longdistance

dispersal. However, whilst mangroves have

common needs to adapt to rigorous environmental constraints

associated with regular seawater inundation, individual

taxa have developed different strategies and

characteristics. Since mangroves are a genetically diverse

group of mostly flowering plants, they may also

have evolved at quite different geological periods, dispersed

at different rates from different locations and developed

different adaptive strategies. Current distributions

of individual taxa show numerous instances of unusual

extant distribution which demonstrate finite dispersal

limitations, especially across open water. Our preliminary

assessment of broad distribution and discontinuities

reveals important patterns. Discontinuities, in the

absence of current dispersal barriers, may be explained

by persistent past barriers. As we learn more about discontinuities,

we are beginning to appreciate their immense

implications and what they might tell us about

past geological conditions and how these might have influenced

the distribution and evolution of mangroves. In

this article, we describe emerging patterns in genetic relationships

and distributions based on both current

knowledge and preliminary results of our studies of molecular

and morphometric characteristics of Rhizophora

species in the Indo West Pacific region.

one of the first ecosystems to be affected by altered sea

levels accompanying global climate change. Responses

of mangrove forests to changing sea levels depend on

reactions of individual plants, yet such responses have

not been addressed experimentally. We report data from

a long-term greenhouse study that assessed physiological

and individual growth responses of the dominant neo-

tropical mangrove, Rhizophora mangle, to levels of

inundation expected to occur in the Caribbean within 50±

100 years. In this study, we grew potted plants in tanks

with simulated semidiurnal (twice daily) high tides that

approximated current conditions (MW plants), a 16-cm

increase in sea level (LW plants), and a 16-cm decrease

in sea level (HW plants). The experiment lasted 2 1/2

years, beginning with mangrove seedlings and termi-

nating after plants began to reproduce. Environmental

(air temperature, relative humidity, photosynthetically

active radiation) and edaphic conditions (pH, redox, soil

sulfide) approximated ®eld conditions in Belize, the

source locale for the seedlings. HW plants were shorter

and narrower, and produced fewer branches and leaves,

responses correlated with the development of acid-

sul®de soils in their pots. LW plants initially grew more

rapidly than MW plants. However, the growth of LW

plants slowed dramatically once they reached the sapling

stage, and by the end of the experiment, MW plants

were 10±20% larger in all measured growth parameters.

Plants did not exhibit differences in allometric growth as

a function of inundation. Anatomical characteristics of

leaves did not differ among treatments. Both foliar C:N

and root porosity decreased from LW through MW to

HW. Relative to LW and HW plants, MW plants had

1±7% fewer stomata/mm2, 6±21% greater maximum

photosynthetic rates, 3±23% greater absolute relative

growth rates (RGRs), and a 30% higher RGR for a

given increase in net assimilation rate. Reduced growth

of R. mangle under realistic conditions approximating

future inundation depths likely will temper projected

increased growth of this species under concomitant

increases in the atmospheric concentration of CO2.

tation are considered and contrasted with ideas of eco-

system restoration. Three reasons for mangrove

rehabilitation: conservation and landscaping; multiple use

systems for high sustainable yield and protection of

coastal areas, are then examined in detail. In each case,

the underlying philosophy and limitations are presented.

The practical problems of site selection for mangrove

planting and techniques for regenerating mangroves are

then considered. Some comments and data are then of-

fered on mangrove ecosystem rehabilitation that is being

carried out world-wide. Comment is made on the paucity

of information. The practice and importance of monitor-

ing and maintaining rehabilitated mangrove ecosystems is

then presented. Finally, there is a discussion on the future

management and research needs of mangrove ecosystem

rehabilitation.

coast of the Guianas are a consequence of the huge particulate discharge of the Amazon. These mud banks shift towards the

northwest, influenced by the combined action of accretion and erosion, a process also affected by periodic variability. Because

of this movement, the coastline is unstable and continuously changing. Such changes determine the structure and composition

of mangrove forests, the only type of vegetation adapted to this dynamic environment. The objectives of this study were to

identify coastal changes that took place over the last 50 years, and to relate them to natural processes of turnover and

replenishment of mangrove forests. These objectives have been achieved through a combination of remote sensing techniques

aerial photographs and SPOT satellite images) and field surveys in the area of the Sinnamary Estuary, French Guiana. Ground

data were collected in representative mangrove forest stands, chosen as a function of their growth stages and their structural

features, from pioneer and young stages to adult, mixed and declining formations. The coastline changes and the mangrove

dynamics over the 1951–1999 period are analyzed through production of synthetic digital maps, showing an alternation of net

accretion (1951–1966) and erosion periods (1966–1991), followed by the present accretion phase. Based on this structural,

functional and historic information, a global scenario of mangrove forest dynamics is proposed, including a model of forest

development, forest gap processes and sedimentological dynamics. The results of this research are discussed within the context

of regional (coastal Amazonian area) and global climate.

Zealand were mapped into lush and stunted categories from SPOT HRV and

Landsat TMimages at 10, 20 and 30m using the maximum likelihood method.

It was found that the TM-generated results were the most accurate at 95%for

lush mangroves and 87.5%for stuntedmangroves. Their corresponding accuracy

levels were lowered to 77.5%and 67.5% in the 20m SPOT XS-derived results.

Both percentages were improved to 80 after the PAN band was incorporated in

the classi® cation at 10m. These results suggest that a high spectral resolution is

more important in accurately mapping mangroves in a temperate zone than a

® ne spatial resolution because it enhances the interpretability of non-mangrove

vegetation and thus increases its confusion with mangroves.

and subsequently analysed using the ERDAS Imagine software to map mangroves

in the Waitemata Harbour of Auckland, New Zealand, a climatically marginal

habitat of mangroves. The methodology in generating the mangrove distribution

maps is described ® rst. The mapped mangroves and their mapping accuracy are

presented and discussed next. The mapping accuracy is achieved at 76% in the

one-tiered mangrove classi® cation scheme. If mapped as two categories based on

density, the thriving, tall mangroves are more accurately mapped (72´5%) than

the sporadically-canopied ones (63´3%) due to their heavy confusion with urban

residential. The merging of the two classes of mangroves after classi® cation results

in an accuracy of 81´4%. In addition to mangrove density, patch size of mangrove

habitats, tidal height and topographic shade are the other identi® ed factors

degrading the mapping accuracy.

by means of parametric classification because of their spectral

similarity to other coastal vegetation despite their habitat

being inside coastal waters. This study aims to improve the

mapping accuracy through incorporation of such spatial

knowledge about mangroves in the Waitemata Harbor of

Auckland, New Zealand, from SPOT data. The spatial knowledge

was combined with spectral knowledge in the mapping.

Supervised classification was found to map stunted and lush

mangroves at an accuracy of, respectively, 46.7 percent and

68.3 percent. These accuracy levels rose, respectively, to

83.3 percent and 96.7 percent after the spatial knowledge was

sequentially incorporated into the mapping. A similar accuracy

level was achieved from knowledge-based spatial reasoning.

If integrated simultaneously with spectral knowledge,

spatial knowledge did not improve the accuracy noticeably

because of difficulty in gaining quality spectral knowledge. It

is concluded that knowledge-based, post-classification processing

considerably improves the accuracy of mapping mangroves

over parametric classification.

coast. Of 2500 households in 21 rural communities (about 13.000 people) near the Caeté estuary, 83% derive subsistence

income, and 68% cash income through use of mangrove resources. The mangrove crab (Ucides cordatus)

is collected and sold by 42% of households, and constitutes a main income source for 38%. Including processing

and trading occupations, over half of the investigated population depend on the mangrove crab for financial income.

Mangrove fishery occupies the lower rural income groups in the fisheries sector. About 30% of households engage

in commercial fishing in or near the mangrove. Illegal commercial and subsistence use of mangrove wood and

bark maintains a considerable number of rural households. In the context of widespread rural poverty in coastal

North Brazil, it is important for mangrove management to take into account subsistence production, which has a

central socio-economic function for the rural poor who live close to the mangroves. Socio-economic priorities in

mangrove villages were, in order of importance, educational quality, occupational options, medical care, the low

level of mangrove product prices, access to electricity and local leadership quality.

became un-sustainable in the early 1990’s due to the un-planned development of this industry and the resulting

self pollution of the farms, the destruction of mangrove forest and the outbreak of viral diseases. Historical data

on fisheries, fishing effort and mangrove coverage were obtained from the province Minh Hai (lately divided

in Ca Mau and Bac Lieu). Analysis of catch and effort data of marine fisheries in the Mekong Delta indicated

a severe danger of over-exploitation of fish stocks and further decline can be expected if fisheries management

only considers the demand for fish. The relation between the total fish catch (t/year), the mangrove area (ha), the

engine capacity (HP) of the fishing fleet and the social incentive for fishing could be described with the model:

Total catch=0.449 Mangrove area + 0.614 Engine capacity + 654 Social factor. One hectare of mangrove forest

supports a marine catch of 450 kg/year

preservation. They also provide a highly caloric timber, used frequently for burning purposes as, e.g. charcoal. The

forestry activity usually ignores the capacity of the mangroves to support the local fisheries. Therefore, it is necessary

to study the relationship between these activities and how they could be managed in order to maximize their benefits,

and at the same time to preserve ecosystem services. This problem was approached by two different modelling

procedures, widely used in natural resources management studies: a dynamic optimization and a simulation model.

The dynamic optimization model gave us some hints about the best allocation of workers between forestry and fishery

sectors. Using the simulation model it was possible to take the data generated and employ it in our first order

conditions equations from the optimization model to find the shadow prices for the resources stocks. The most

important variable in the simulation is the forest growth rate, since the fishery production is directly dependent on

the area of mangrove forest.

mangroves are reviewed, and ® ve different methodologies identi® ed. Landsat TM,

SPOT XS and CASI data of mangroves from the Turks and Caicos Islands, were

classi® ed using each method. All classi® cations of SPOT XS data failed to

discriminate satisfactorily between mangrove and non-mangrove vegetation.

Classi® cation accuracy of CASI data was higher than Landsat TMfor all methods,

and more mangrove classes could be discriminated. Merging Landsat TM and

SPOT XP data improved visual interpretation of images, but did not enhance

discrimination of different mangrove categories. The most accurate combination

of sensor and image processing method for mapping the mangroves of the eastern

Caribbean islands is identified.

interpolation approach to convert witness tree records of the U.S. General Land Office

(GLO) survey from point to polygon data, which better described continuously distributed

vegetation. The witness tree records (1839–1866) were processed for a 3-million ha

landscape in northern Wisconsin, U.S.A. at different scales. We provided implications of

processing results at each scale. Compared with traditional GLO mapping that has fixed

mapping scales and generalized classifications, our approach allows presettlement forest

landscapes to be analysed at the individual species level and reconstructed under various

classifications. We calculated vegetation indices including relative density, dominance, and

importance value for each species, and quantitatively described the possible outcomes

when GLO records are analysed at three different scales (resolution). The 1*1-section

resolution preserved spatial information but derived the most conservative estimates of

species distributions measured in percentage area, which increased at coarser resolutions.

Such increases under the 2*2-section resolution were in the order of three to four

times for the least common species, two to three times for the medium to most common

species, and one to two times for the most common or highly contagious species. We

mapped the distributions of hemlock and sugar maple from the pre-European settlement

period based on their witness tree locations and reconstructed presettlement forest

landscapes based on species importance values derived for all species. The results

provide a unique basis to further study land cover changes occurring after European

settlement.

various initiatives are underway to assess their current coverage and loss in

cover. These ecosystems occur as thin strips along coastlines or rivers and, due

to the strong environmental gradients present, mangroves show high spatial

variability along short transects. Remote sensing tools that offer high spatial

resolution mapping and high information content are needed to provide good

differentiation of the various mangrove zones and types. The added complexities

of tropical atmospheric conditions provide further challenges in terms of the

selection of sensors and image analysis methodologies. This paper explores the

possibility of combining a high spatial/spectral resolution scanner, ‘Compact

Airborne Spectrographic Imager’ (CASI), with the airborne National Aeronautics

& Space Administration’s polarimetric radar, ‘AIRSAR’, for mapping

and monitoring of mangrove estuaries. The Daintree River estuary in far North

Queensland, Australia was chosen for this study due to its diversity of mangrove

species. Imagery acquired by both the CASI airborne scanner (14 bands, 2.5mpixel)

and the AIRSAR (L- and P-band polarimetry, C-band interferometry, 10m pixel)

has been used to produce detailed maps of the mangrove zones in the estuary.

The advantages and difficulties associated with multi-source data

integration are investigated in this paper. While radar provides general

structural information in relation to mangrove zonation, high-resolution

hyperspectral scanners allow for finer-detailed analysis and green-biomass

information. Classifications (maximum likelihood) of both the individual and

integrated datasets are performed, with the latter producing more accurate

results. Application of a hierarchical neural network classification is also

explored, where the more general mangrove zones are separated first based

on structural information, then species or specie-complexes are extracted in

subsequent levels using spectral differences.

northwest Mexico and evaluates the spatiotemporal change in the mangrove area over the last three decades

using Landsat MSS and TM imagery. Local ethnobotanical uses of the mangrove forest and local perceptions

about the status and recent development of the mangrove forest cover are also analyzed. The results of

interviews with 54 inhabitants of four fishing villages in the study area indicated that, overall, Laguncularia

racemosa is the most frequently used species in this region of the Mexican Pacific coast, where it serves

as firewood and a construction material, particularly for walls and fences. The next-ranked species were

Avicennia germinans, which is used for tea, and Rhizophora mangle, which is used for tanning; both these

species also serve medicinal purposes. There was a discrepancy between the assessment of actual changes

in the mangrove cover and what people perceived them to be. These findings are discussed from a

socioeconomic (utilization) and an ecological (functionality) point of view and in relation to the use of

remote sensing as a tool. The utilization pattern is also discussed against the background of mangrove cover

variation.

highly productive ecosystems that provide large quantities

of organic matter to adjacent coastal waters in the

form of detritus and live animals (fish, shellfish). The

detritus serves as a nutrient source and is the base of an

extensive food web in which organisms of commercial

importance take part. In addition, mangrove ecosystems

serve as shelter, feeding, and breeding zones for crustaceans,

mollusks, fish of commercial importance, and resident

and migratory birds. Although mangroves in the

United States are protected, the systematic destruction of

these ecosystems elsewhere is increasing. Deforestation

of mangrove communities is thought to be one of the

major reasons for the decrease in the coastal fisheries of

many tropical and subtropical countries.

There is evidence to propose a close microbe-nutrient-

plant relationship that functions as a mechanism to

recycle and conserve nutrients in the mangrove ecosystem.

The highly productive and diverse microbial community

living in tropical and subtropical mangrove ecosystems

continuously transforms nutrients from dead

mangrove vegetation into sources of nitrogen, phosphorus,

and other nutrients that can be used by the plants. In

turn, plant-root exudates serve as a food source for the

microorganisms living in the ecosystem with other plant

material serving similarly for larger organisms like

crabs.

This overview summarizes the current state of knowledge

of microbial transformations of nutrients in mangrove

ecosystems and illustrates the important contributions

these microorganisms make to the productivity of

the ecosystems. To conserve the mangrove ecosystems,

which are essential for the sustainable maintenance of

coastal fisheries, maintenance and restoration of the microbial

communities should be undertaken. Inoculation

of mangrove seedlings with plant-growth-promoting

bacteria may help revegetate degraded areas and create

reconstructed mangrove ecosystems.

Subsidised by the government, it quickly became an important export industry and Thailand has been the world’s

largest producer of tiger shrimp since 1991. However, the development of the shrimp farming industry in Thailand

over the last 20 years in relation to its use of mangrove ecosystems is an example of sequential exploitation of natural

resources witnessed through the shift in farm development from one region to another. This sequential exploitation

has caused widespread degradation of mangrove ecosystems, and the benefits of the industry may be less than

perceived as a result of subsidies and environmental and social impacts. This study follows the development of shrimp

farming in Thailand from the 1940s to 1997 and studies national legislation and associated government policy as

examples of driving forces behind this development. From our findings it appears that the development of legislation

has not followed the same pace as the development of the industry, neither temporally, nor in content nor

implementation, and contradictory policies have arisen.

with paired sites that had been cleared of mangroves by human activity. Forested sites included plantations and natural stands of

Sonneratia alba and natural Rhizophora mucronata stands. Two methods of stake netting were used to take quantitative samples;

method one used a single 100-m-long, 18-mm mesh net, method two used paired 24-m-long, 1-mm mesh netsdsamples were taken

during seven different months in 2002. Mean abundances of fish found in mangrove and cleared sites, respectively, were 0.004 m-2

and 0.014 m-2 (method 1) and 0.21 m-2 and 0.25 m-2 (method 2). Thirty species were sampled, 12 of which were found exclusively

in mangrove habitats and 10 of which were limited to cleared sites. The most abundant species in mangrove plots was Atherina afra

(although it was only found in two, large catches); the most abundant in cleared plots was Gerres oyena (found frequently). Mean

abundance (using data pooled for all sites) was significantly higher in cleared, compared with forested, sites, and multivariate

analysis showed significantly different community structures in the two habitat types. There was large variation in catch rates

between dates and sites, with one forested site recording no catches at all. These results do not support the predator refuge

hypothesis (which predicts higher abundance of juvenile fish inside mangroves). The low abundance of fish recorded in the mangrove

sites may have been due to site-specific factors determining fish abundance within mangrove forests, to the sampling techniques used

or to relatively high turbidities at these sites.

attention world wide for several reasons. Firstly, the

long ignored ecological and environmental values of

mangrove forests have been documented for many

mangrove areas in the world. Secondly, there is a high

subsistence dependence on natural resources from

mangrove forests. In addition, large losses of mangroves

have occurred throughout the world leading to

coastal erosion, decline of fishery resources and other

environmental consequences, some of which in need of

urgent attention. Finally, governments throughout the

world are showing commitments towards sustainable

use of mangrove areas. This paper outlines the activities

of mangrove restoration and management around

the world with particular emphasis on Eastern Africa.

As noted here, extensive research has been carried out

on the ecology, structure and functioning of the mangrove

ecosystem. However, the findings have not been

interpreted in a management framework, thus mangrove

forests around the world continue to be over-exploited,

converted to aquaculture ponds, and polluted. We

strongly argue that links between research and sustainable

management of mangrove ecosystems should be

established.

back to the 1940s and 1950s when some families informally designated mangrove

areas under their care and management. The 1960s and 1970s saw several exogenous

events that led to the progressive denudation of mangrove stands and the

decline in fish catch per fishing trip. This article draws attention to the forces that

prompted coastal villages and external agents to collaborate with the national and

local government units in resource rehabilitation. It also assesses the performance

of a coastal resources comanagement project at Cogtong Bay.

Landsat TM images (1986, 1993, 1999) were examined to

assess potential losses in the mangrove forests of the

Teacapán–Agua Brava lagoon system, Mexico. A binary

change mask derived from image differencing of a band 4/3

ratio was employed to calculate any changes within this forested

wetland. The results indicate that by 1986 approximately

18% (or 86 km2) of the mangrove area under study

was either dead or in poor condition. The majority of this damage

had occurred in the eastern section of the Agua Brava

basin, which coincides, with the reports of the elderly fishermen.

Examination of aerial photographs from 1970 revealed

no adverse impacts in this area and would suggest, as postulated

by the fishermen and other scientists, that modifications

in environmental conditions following the opening of a canal,

Cuautlá canal, in 1972 may have initiated the large-scale mortality.

Although these areas of impact are still developing, the

results from the satellite data indicate that the majority of the

more recent changes are occurring elsewhere in the system.

Obvious in the 1999 satellite data, but not so in the 1993, are

large areas of mangrove degradation in the northern section of

the Teacapán region. In the Agua Brava basin, the more recent

transformations are appearing on the western side of the

basin. Since long-term records of environmental conditions

are absent, it is difficult to determine why these latest changes

are occurring or even if the earlier losses were the result of the

canal. Potential agents of change that have recently been observed

include a hurricane, a second canal, and the uncontrolled

expansion of the Cuautlá canal since 1994.

of a cartographic database for a synoptic Geographic

Information System (GIS). Its purpose is the storage and evaluation

of the heterogeneous datasets of the interdisciplinary

scientific research program MADAM (Mangrove Dynamics and

Management), which aims to develop recommendations for a

tailored integrated coastal management scheme for the mangrove

ecosystem at Braganc¸ a (North Brazil). The article describes

the integration of remote sensing data, aerial photographs,

as well as point data provided by fieldwork from

different scientific fields. Using various innovative processing

techniques and different scale-resolution levels, an assessment

of temporal–spatial changes of the mangrove peninsula

and the adjacent rural socioeconomic impact area, the type of

mangrove structure, as well as a land-use cover analyses was

undertaken. The definition of the spatial level of detail was

found to be a major issue in the development of the GIS, as

well as during the processing and analysis procedures. A division

between strong and weak patterns in the mangrove ecosystem

could be made, which implies different management

measures and sets of specific interdisciplinary studies and

monitoring at hierarchical scales.

The major advantage of using Geographic Information

Systems (GIS) is their ability to store, retrieve, and

handle large datasets of very heterogeneous origin and

to represent these in visual format (i.e., on geographic

maps) (Burrough 1998; Fabbri 1998). Heterogeneous

datasets occur also in integrated coastal management

(ICM) initiatives (Richter and others 2001), where the

GIS provides a tool to evaluate coastal development

alternatives on a scenario-planning basis, in order to

explore possibilities to reach ecological, economic, and

social sustainability in the coastal zone (Fabbri 1998;

Green and others 2000). Stalmans and others (2001)

have suggested that the GIS has a major advantage for

all types of environmental management, as it is capable

of storing the information gathered in long-term monitoring

programs, thus capturing the wealth of knowledge

from one generation of managers and researchers

to the next. Furthermore, remote sensing imagery can

be incorporated into the GIS, adding further information

layers in a cost-effective fashion (Green and others

2000).

The usefulness of such tools depends on the quality

of the data and on the availability of information on the

geometric accuracy. Both aspects must be addressed

and quantified in order to provide a sound scientific

basis for integrated management policy formulations

(Hunsaker and others 2001), as otherwise it would

endanger the trust in the virtual outputs of such systems.

Green and others (2000) have pointed out that

habitat or resource maps in GIS of poor or unknown

accuracy are of little use as a basis for planning and

management.

structures include a contribution to the geomorphological stability of mangrove soils through sediment trapping and binding. In this

study, we used feldspar marker horizons and sediment pins to investigate the influence of three different functional root types—prop

roots in Rhizophora spp., root knees in Bruguiera gymnorrhiza, and pneumatophores in Sonneratia alba—on vertical accretion and

elevation change in three mangrove forests in the Federated States of Micronesia. Prop roots facilitated vertical accretion

(11.0mmyear-1) more than pneumatophores or bare soil controls (mean, 8.3mmyear-1). Sediment elevation, on the other hand,

increased at an average rate of only 1.3mmyear-1 across all root types, with rate differences by root type, ranging from
0.2 to

3.4mmyear-1, being detected within river basins. This investigation demonstrates that prop roots can assist in the settling of

suspended sediments from estuarine waters, yet prop root structures are not as successful as pneumatophores in maintaining

sediment elevation over 2.5 years. As root densities increase over time, an increase in turbulence-induced erosion and in shallow

subsidence as organic peat layers form is expected in Micronesian mangrove forests.

with different degrees of fragmentation on Andros Island, Bahamas. Estuaries were classified a priori into

four fragmentation categories: totally fragmented (no surface water connectivity to the ocean), partially

fragmented, minimally fragmented, and unfragmented (unimpeded surface water connectivity through the

estuary to the ocean). Visual surveys (n = 159) were conducted in thirty estuarine systems using snorkeling

gear in four habitat types: flat, mangrove, rock, and seagrass. Fish species density differed significantly

among habitat types and among estuaries with different degrees of fragmentation. Highest species density

occurred in rock habitats in unfragmented or minimally fragmented estuaries; lowest species density was in

totally fragmented estuaries. Assemblages in unfragmented and minimally fragmented estuaries were characterized

by presence of reef-associated (e.g., damselfish and parrotfish) and transient marine (e.g., jacks)

taxa. In completely fragmented sites, assemblages were dominated by species tolerant of temperature and

salinity extremes (e.g., sheepshead minnow). Multi-dimensional scaling suggested fish assemblages in mangrove

and rock habitats experienced the greatest impact of estuary fragmentation (i.e., the most differentiation

among surveys in estuaries with different fragmentation status). Fish assemblages were especially

variable among partially fragmented estuaries (i.e., estuaries where hydrologic connectivity was maintained

by a culvert), suggesting hydrologic connectivity through culverts may not be sufficient to maintain habitat

quality, recruitment dynamics, or upstream movements by vagile organisms. These data reveal effects fragmentation

has on faunal assemblages, and demonstrates that faunal presence/absence may guide initiatives

to conserve and restore sub-tropical estuaries.

three phases. The first was the initial experimental phase where ‘persistent vegetative cover’ was the primary goal.

Following the routine achievement of that criterion, coastal restoration entered a new phase where wetland

compensatory mitigation became the primary driving force and ‘functional equivalency’ was considered the ultimate

goal. We have now entered the third phase where ‘ecological restoration’ and ‘ecosystem restoration’ are the

buzzwords. Using case studies in southern Florida, it is suggested that the political will is not there to properly fund

effective wetland compensatory mitigation programs and thus the success of these is marginal and cannot be expected

to improve. Wetland regulatory programs are still needed, but the future of coastal wetland management is more

likely to be successful with an emphasis on conservation and restoration programs with mitigation:compensation

being only one small part of the entire program. Ecologically based goal setting will be an important future element

of successful non-regulatory wetland management programs.

northern Florida, coexisting trees of Laguncularia racemosa

and Avicennia germinans were either fertilized with

nitrogen or phosphorus, or not fertilized (controls). We

aimed to test whether nutrient additions differentially

altered photosynthetic performance and resource utilization

in these two species. In control trees, photosynthetic

rates were higher in L. racemosa than A. germinans.

However, leaf nitrogen concentrations were higher in A.

germinans than L. racemosa. Avicennia germinans responded

to fertilization with nitrogen by increasing leaf

nitrogen concentrations and rates of photosynthesis such

that they were equivalent to photosynthesis in L.

racemosa. Laguncularia racemosa did not show a

response to nitrogen additions. Neither species showed

strong responses to phosphorus fertilization. Avicennia

germinans had high photosynthetic water-use efficiency

(photosynthesis/transpiration), but low photosynthetic

nitrogen-use efficiency (photosynthesis/leaf nitrogen). In

contrast, L. racemosa had comparatively low photosynthetic

water use efficiency and high photosynthetic

nitrogen use efficiency. Leaf level characteristics lead

us to hypothesize that coexistence of A. germinans and L.

racemosa should occur where nitrogen levels are low and

salinity is moderate, or at least moderate for some period

of the year.

Rhizophora mangle L. are extensive in the Caribbean.

We fertilized dwarf trees in Almirante Bay, Bocas del Toro Province, north-eastern

Panamá with nitrogen (N) and phosphorus (P) to determine (1) if growth limitations

are due to nutrient deficiency; and (2) what morphological and/or physiological factors

underlie nutrient limitations to growth.

2. Shoot growth was 10-fold when fertilized with P and twofold with N fertilization,

indicating that stunted growth of these mangroves is partially due to nutrient deficiency.

3. Growth enhancements caused by N or P enrichment could not be attributed to

increases in photosynthesis on a leaf area basis, although photosynthetic nutrient-use

efficiency was improved. The most dramatic effect was on stem hydraulic conductance,

which was increased sixfold by P and 2·5-fold with N enrichment. Fertilization with P

enhanced leaf and stem P concentrations and reduced C : N ratio, but did not alter leaf

damage by herbivores.

4. Our findings indicate that addition of N and P significantly alter tree growth and

internal nutrient dynamics of mangroves at Bocas del Toro, but also that the magnitude,

pattern and mechanisms of change will be differentially affected by each nutrient.

few species can tolerate the hydrological and edaphic

conditions that prevail in mangrove habitats. The small

pantropical mangrove species pool is also the basis for

asserting that mangrove forests are easy to rehabilitate, at

least in terms of tree species composition. The high com-

plexity of the animal and microbial component of man-

grove ecosystems is not addressed in this article. The

following questions are useful as a guide for evaluating the

invasion of plant species into mangrove habitats: (1) Is

the invading species a halophyte? (2) What conditions of

the environment is the invading species occupying and how

long will those conditions last? (3) What is the geographic

location of the invasion, does it penetrate the forest or is it

only at the edge? (4) Is the invasion a short-term response

to changes in microsite conditions? (5) Is the invasion the

result of a long-term shift in the mangrove habi-

tat?

de México. El primer tema analizado es la biogeografía, describiendo la diversidad y

composición de los manglares de las dos costas del país, así como los límites de su

distribución. La distribución, composición y fisonomía de las comunidades de manglar

están influidas por los cambios latitudinales en la temperatura y la precipitación, pero

localmente dependen de la geomorfología, el substrato, la salinidad, la inundación y el

relieve. Los estudios al presente sugieren que las interacciones bióticas también pueden

influir en los patrones de zonación observados y que los óptimos fisiológicos y

ecológicos de las especies no siempre coinciden espacialmente. La caída de hojarasca

se ha estudiado en las costas del Golfo de México y del Océano Pacífico. También se

analizaron trabajos sobre descomposición de hojarasca y su dinámica, de fenología y las

estimaciones de deforestación, la que al parecer es de 5% anual. Se hace un análisis de

las fuentes de perturbación, como la construcción de infraestructura turística,

camaronicultura y sustitución por campos de cultivo y potreros, las actividades

industriales y los errores derivados del cambio de la dinámica hidrológica de estuarios

completos. La conclusión es que los retos son muy grandes y es necesaria una mayor

cantidad de estudios sobre la biología, ciclos de vida, valuación y manejo, distribución y

formas de drenaje de los manglares.

the Ranong mangrove forest ecosystem on the Andaman Sea coast of southern Thailand. After a history of commercial

exploitation the mangroves along the Klong Ngao tidal creek have been assigned conservation status within a new Ranong

Biosphere Reserve established in 1997. Over the past 12 years, several areas of mangrove destroyed or degraded by wood

harvesting, tin mining and aquaculture, have been rehabilitated on a pilot basis by planting monocultures of mangrove

seedlings using four common local species (Rhizophora apiculata, R. mucronata, Bruguiera cyclindrica and Ceriops tagal).

These plantation forests with different past management histories were compared with a natural, mixed, mature

mangrove forest which has been conserved for about 40 years. Macrofauna were sampled within a 100 m2 vegetation

quadrat in each study site. Crustaceans were sampled quantitatively by 3
15 min timed hand catches per site. Molluscs

were sampled in 3
m2 quadrats positioned around three randomly selected trees in each vegetation quadrat. The lowest

crustacean and molluscan diversity was recorded from the former tin mining site. The highest diversity was recorded from

a Rhizophora plantation in the natural mixed forest area for both crustaceans and molluscs. The vegetation community

structure was not correlated with the environmental variables measured, or with macrofauna community structure. Of the

environmental parameters chosen, the crustacean community structure was best expressed by shore level, while for

molluscan diversity and abundance it was soil moisture content. The macrofauna community structure at the tin mining

site was significantly different to the other sites, and was dominated by a single species of crab, Metaplax elegans. Grapsid

crabs, especially sesarmid species, dominated over ocypodid crabs in the mature forest site, whereas Uca species and other

ocypodids were more abundant than grapsids in the degraded concession forest area. Snails of the families Neritidae and

Ellobiidae were the most abundant molluscs in the mature forest, whereas Littoriinidae, Assimineidae and Potamidae

species were more representative of the younger plantation sites. The findings from this study suggest that some of these

well represented families of mangrove macrofauna could be used as indicators of ecological change as part of a long term

environmental monitoring programme in Ranong and other areas in Southeast Asia where mangroves are being

rehabilitated.

Remote Sensing on Remote Sensing of the Coastal Marine Environment to

highlight recent advances in knowledge of remote sensing of the coastal zone and

to define a series of priorities where future research into the application should

be addressed.

Advances were identified in the benefit of high spatial and spectral resolution

data and complementary remote sensing techniques (e.g. optical and acoustic,

optical and Synthetic Aperture Radar (SAR)). Further benefits are identified in

rapid and more frequent data acquisition, faster and more automated processing

and a greater sampling intensity over conventional field-based techniques. Issues

associated with adoption of remotely sensed data for management are discussed.

Research priorities include the need for improved understanding and

description of biotope classes and the functional interpretation of biotope

maps and continued developments in understanding the radiative transfer

properties of coastal environments. New knowledge is required on spatial and

temporal variations of water column optical properties and its constituents.

Methods for the best approaches to processing hyperspectral data require further

investigation, as does the need for further testing of hyperspectral sensors for

bottom type discrimination using data obtained at space-borne altitudes. Areas

of value which continue to remain poorly investigated include the improvements

to be gained from synergistic use of multi-wavelength remote sensing

approaches, change detection techniques and multi-temporal comparisons and

knowledge-based approaches to improve classification. The importance of

specifically dedicated coastal zone sensors is discussed, as is alternative means of

deployment (e.g. International Space Station (ISS) and Un-inhabited Aerial

Vehicles (UAVs)). The potential role of airborne digital photography for marine

mapping is highlighted. The lack of accurate near-shore bathymetric data is

identified as a key limitation in the application of geospatial data to coastal

environments.

use/cover classes present similar spectral signatures and are misclassified. This paper presents a procedure for mapping land use/

cover combining the spectral information from a recent image and data about spatial distribution of land use/cover types obtained

from outdated cartography and ancillary data. Two fuzzy maps, which indicate the membership of each land use/cover class, were

generated from the ancillary and spectral data, respectively, using an artificial neural networks approach. The combination of both

maps was obtained using fuzzy rules. In comparison with spectral classification, this procedure allowed a statistically significant

increase of accuracy of land use/cover classification (from 67% to 79%). The advantages of this procedure for combining spectral

and ancillary data, with regard to others previously published in the literature, are that it allows one to take into account previous

mapping efforts and to establish relationships between land use/cover and environmental variables specific to the mapped area.

that a wide variety of factors, including salinity, desiccation,

disturbance, competition and predation, may

a¤ect the distribution and abundance of species. Field

studies were done to examine the relative importance

of several of these factors in the establishment and early

survival of Ceriops tagal, a species common in mid- to

high-shore regions of mangrove forests in northern

Australia. The fate of marked and tethered propagules

was followed to estimate the range of dispersal and the

intensity of predation. Propagules were artiÞcially

planted under di¤erent thicknesses of shade cloth

(none, 30%, 80%) and in di¤erent habitats (clearing,

forest, clearing-forest fringe) to examine the e¤ects of

light and soil conditions on survival and growth.

Results suggested that dispersal was very limited: only

9% of marked propagules were ever found more than

3m from the parent tree. Losses to predators were

great, with 83% of tethered propagules being damaged

or consumed within 3 months. On average, 56% of

planted propagules survived for at least 6 weeks and

76% of these initiated growth. Survival in clearings was

lower than in other habitats, with 29% fewer surviving

six weeks and 48% fewer surviving 15 months. The

growth of seedlings was correlated with soil temperature,

but the e¤ects of treatments were complex.

Overall, results indicated that poor dispersal and establishment

were the main factors likely to limit the colonisation

and population growth of this species.

patterns, oceanic and atmospheric circulation, rate of rising sea level, and the frequency,

intensity, timing, and distribution of hurricanes and tropical storms. The magnitude of these

projected physical changes and their subsequent impacts on coastal wetlands will vary

regionally. Coastal wetlands in the southeastern United States have naturally evolved under

a regime of rising sea level and specific patterns of hurricane frequency, intensity, and

timing. A review of known ecological effects of tropical storms and hurricanes indicates

that storm timing, frequency, and intensity can alter coastal wetland hydrology, geomorphology,

biotic structure, energetics, and nutrient cycling. Research conducted to examine

the impacts of Hurricane Hugo on colonial waterbirds highlights the importance of longterm

studies for identifying complex interactions that may otherwise be dismissed as stochastic

processes.

Rising sea level and even modest changes in the frequency, intensity, timing, and

distribution of tropical storms and hurricanes are expected to have substantial impacts on

coastal wetland patterns and processes. Persistence of coastal wetlands will be determined

by the interactions of climate and anthropogenic effects, especially how humans respond

to rising sea level and how further human encroachment on coastal wetlands affects resource

exploitation, pollution, and water use. Long-term changes in the frequency, intensity, timing,

and distribution of hurricanes and tropical storms will likely affect biotic functions (e.g.,

community structure, natural selection, extinction rates, and biodiversity) as well as underlying

processes such as nutrient cycling and primary and secondary productivity.

Reliable predictions of global-change impacts on coastal wetlands will require better

understanding of the linkages among terrestrial, aquatic, wetland, atmospheric, oceanic,

and human components. Developing this comprehensive understanding of the ecological

ramifications of global change will necessitate close coordination among scientists from

multiple disciplines and a balanced mixture of appropriate scientific approaches. For example,

insights may be gained through the careful design and implementation of broadscale

comparative studies that incorporate salient patterns and processes, including treatment

of anthropogenic influences. Well-designed, broad-scale comparative studies could serve

as the scientific framework for developing relevant and focused long-term ecological research,

monitoring programs, experiments, and modeling studies. Two conceptual models

of broad-scale comparative research for assessing ecological responses to climate change

are presented: utilizing space-for-time substitution coupled with long-term studies to assess

impacts of rising sea level and disturbance on coastal wetlands, and utilizing the moisturecontinuum

model for assessing the effects of global change and associated shifts in moisture

regimes on wetland ecosystems. Increased understanding of climate change will require

concerted scientific efforts aimed at facilitating interdisciplinary research, enhancing data

and information management, and developing new funding strategies.

ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral

reef fish often inhabit mangroves2–5, but the importance of these

nurseries to reef fish population dynamics has not been quantified.

Indeed, mangroves might be expected to have negligible

influence on reef fish communities: juvenile fish can inhabit

alternative habitats and fish populations may be regulated by

other limiting factors such as larval supply or fishing6. Here we

show that mangroves are unexpectedly important, serving as an

intermediate nursery habitat that may increase the survivorship

of young fish. Mangroves in the Caribbean strongly influence the

community structure of fish on neighbouring coral reefs. In

addition, the biomass of several commercially important species

is more than doubled when adult habitat is connected to mangroves.

The largest herbivorous fish in the Atlantic, Scarus

guacamaia, has a functional dependency on mangroves and has

suffered local extinction after mangrove removal. Current rates

of mangrove deforestation are likely to have severe deleterious

consequences for the ecosystem function, fisheries productivity

and resilience of reefs. Conservation efforts should protect

connected corridors of mangroves, seagrass beds and coral reefs.

mangroves as feeding habitats. In this study we tested the degree to which Caribbean mangroves are

utilised as feeding grounds by the fish community from adjacent seagrass beds. Stable carbon and

nitrogen isotope analyses were performed on several potential food items from seagrass beds and

adjacent mangroves, on muscle tissue of 23 fish species from seagrass beds on a Caribbean island

(Curaçao, Netherlands Antilles), and on juveniles of 2 common reef fish species, Haemulon flavolineatum

and Ocyurus chrysurus, from seagrass beds in 7 bays on 5 Caribbean islands. Only the

herbivore Acanthurus chirurgus and the carnivore Haemulon chrysargyreum appeared to feed

predominantly in the mangrove habitat, whereas the carnivores Mulloidichthys martinicus and O.

chrysurus (only on 2 islands) showed a stable carbon signature suggestive of food intake from the

mangrove as well as the seagrass habitat. The piscivore Sphyraena barracuda foraged on fish schooling

at the mangrove/seagrass interface. For the other 18 seagrass fish species, which contributed

86% of the total seagrass fish density, the contribution of food sources from the mangroves was minor

to negligible. The same was true for H. flavolineatum and O. chrysurus on most of the other

Caribbean islands. The results contrast with the situation in the Indo-Pacific, where intertidal

mangroves serve as important feeding habitats for fishes from adjacent systems during high tide. This

difference is most probably explained by both the absence of large tidal differences on Caribbean

islands and the greater food abundance in seagrass beds than in mangroves.

1996 to July 1997 in the channel of Bacalar Chico in southern of Quintana Roo state. Litter was

collected bimonthly in duplicate baskets at five sites. Four mangrove species were present in the study

area, but R. mangle dominated widely. Leaf production comprised 99.8% of total litter fall biomass,

being the highest in July and September 1996 (0.27 g·dry wt·m-2·day-1 and 0.28 g·dry wt·m-2·day-1

respectively). Although, the flowers and the fruits represented less of 1% of total litter production, it was

clear that the reproductive season was coincident with the highest values of temperature and

precipitation, both occurring in September. Mangrove in Quintana Roo produced a total litter fall of 2.61 t

dry wt ha-1year-1. Mangroves of Quintana Roo must be protected and used with conservation criteria.

of mangroves in Myanmar, including their formation

and their economic and ecological importance. Economic

importance includes fisheries, fuel-wood, charcoal

production, construction materials and medicine,

while ecological importance includes shoreline stabilization,

protection from wind and storms, coastal ecosystem

stability and biodiversity protection. Myanmar’s coastal

areas were in good condition until 30 years ago. However,

population increase and political instability have

caused environmental and economic damage and threaten

recovery. Awareness of the importance of the biodiversity

of the coastal ecosystem and its endangered situation

has led to the implementation of measures to ensure

sustainable development and conservation.

sensing system or product that is “optimal” for a vant constraints (e.g., cost or time). The development of

specific coastal environment and monitoring or modeling such an approach is timely, given two major changes

problem, an objective and replicable framework to guide leading to an increase in the number of potential users

these operations is essential. A framework has been de- of remotely sensed data. These changes include: (1) inveloped

for coastal environments, combining concepts creases in the number and type(s) of commercial and

from remote sensing and landscape ecology to provide re- government imaging sensors (A.S.P.R.S., 1996; Aplin et

motely sensed data users with an objective basis for se- al., 1997); and (2) the proliferation of geographic inforlecting

“optimal” data sets and processing techniques. mation systems (GIS) and other software packages with

The framework was applied to case studies in: coastal image display and analysis capabilities. At present there

wetlands of southern California; coastal wet-dry tropical are around 10 commercially available satellite image data

wetlands in Northern Territory, Australia; and a rapidly sets, with spatial resolutions ranging from 5.0 m to 1.1

urbanizing coastal catchment in southeast Queensland, km and panchromatic to multispectral wavebands. In the

Australia. Results established for each case study demon- near future there are expected to be up to 30 satellites

strated that the framework functioned effectively in dif- with spatial resolutions ranging from 1.0 m to 2.5 km and

ferent coastal environments and provided more accurate multispectral to hyperspectral wavebands (A.S.P.R.S.,

results than ad hoc solutions.

understood. In Kosrae, Federated States of Micronesia, where mangrove wood is harvested for local use, most natural

gaps were < 50 m2, whereas most logging gaps were > 100 m2. Interior zones, where access is facilitated by roads, were

the most heavily exploited. Although the forests contained 11 species, two species were primarily responsible for gap

formation. Natural gaps were caused mainly by broken stems and large branches of Sonneratia alba trees, whereas

logging gaps were created primarily by harvesting Rhizophora apiculata trees. Most natural gaps were formed by the

fall of more than one tree or branch. Seedling densities were higher in logging gaps than in natural gaps and higher in

gaps than under intact canopy. Bruguiera gymnorrhiza was the most common seedling species in gaps and under intact

canopy. Relative rates of growth in height were faster in gaps than under intact canopy for R. apiculata and B. gymnorrhiza

seedlings. Current harvesting practices on the island do not seem to be altering species richness, although R.

apiculata may become less common as gaps are increasingly captured by B. gymnorrhiza.

of canopy structure on the polarimetric radar response of mangrove forests. It

complements the experimental and theoretical study of closed canopies presented

in the previous papers by analysing two diVerent mangrove stands of equal

biomass but which greatly diVer in their structure. For the three considered

frequencies (C-, L- and P-band), experimental observations show that the backscattering

from the open declining stand is higher than that of the closed forest.

The corresponding enhancement factor increases with wavelength and shows

maximum values for the HH polarization. The identi? cation of the scattering

mechanisms occurring between the incident radar wave and the forest components

was performed with the assistance of a polarimetric scattering model based on a

radiative transfer approach. For the co-polarizations, results of the simulation

study con? rm that the backscatter enhancement is mainly due to an increase of

either the surface scattering or the interaction component. For the crosspolarization

HV at L- and P-bands, the increase of the volume component,

originating from a stronger interaction with bigger branches, is found to be

responsible for the observed enhancement. These ? ndings con? rm the large eVect

of the canopy structure on the forest backscatter and give rise to two important

applications. First, the mapping of open declining mangrove stands appears

feasible by using either the backscattering coeYcient values, especially at P-HH

and P-HV, or the HH-VV phase diVerence at P-band. Second, the use of the

s°–biomass statistical relationships must be restricted to homogeneous closed

canopies.

Pichavaram, situated on the southeast coast of India. Nine species of shrimps dominated with Metapenaeus

monoceros, M. brevicornis and Penaeus indicus were recorded. This shrimp resource was higher in mangrovelined

waters than that in neritic waters. This field observation was experimentally proved using litter bags. The

21 21 average catch around the litter bags was 0.80 individuals day for Rhizophora leaves, 1.6 ind. day for

21 Avicennia leaves and 0.16 ind. day in control. In general, abundance of juvenile shrimps was the highest around

the leaves that were decomposed for 40 days and colonized with high counts of nitrogen-fixing azotobacters.

Finally, a ‘vegetation trap’ technique using mangrove leaves has been proposed for efficient schooling of juvenile

shrimps. There was about 3-fold increase in number of shrimp juveniles around the trap than at control waters.

wetland environment in southern Louisiana. Accuracies were estimated as 77% and 81.5% for the pre- and postclassifications

that included water, emergent vegetation, floating vegetation, and mud flats. From the two classifications,

areas of emergent vegetation loss were identified. The classifications and change map were compared to

similar output generated from high resolution color infrared photography. The comparison showed spatial scale of the

sensor was the most important factor in separation of classes in this type of wetland environment. Classifications

derived by using the TM images provided good class separation when one class dominated more extensive areas (>30

ml, but not when mixtures of wetland types were on the same order as the TM sensor spatial resolution. Boundary

pixel mixtures were problematic, however problems also occurred in areas of fairly continuous canopies containing

small pockets of water and floating vegetation, and in areas of degrading marsh. Both areas were predominately

misclassified as emergent vegetation. In the case of change detection, loss of emergent vegetation occurring as small

pockets was not identified, whereas loss of degraded marsh was identified but the spatial continuity and extent

overemphasized. In combination, these misclassifications resulted in the TM change analysis overpredicting emergent

vegetation loss by about 40%

and geographical extent of mangrove ecosystems are unknown in Madagascar.

For the first time, the deltaic complex of Mahajamba bay has been surveyed,

using SPOT 1 and SPOT 2 imagery. An intensive ® eld survey together with

complete aerial coverage at a scale of 1 : 40 000 were used for the validation of

the digital classi® cation. The accuracy of cartographic products and of vegetation

changes is closely related both to the adopted image processing methods and to

the season of satellite data acquisition. The main input of the present contribution

is to provide precise descriptions and mapping of the mangroves in Madagascar

using high resolution remote sensing technology to assess conspicuous changes.

Some conspicuous limitations of satellite data have also been noted. Nevertheless

the results can be used for conservation and management purposes.

Indus delta in Sindh and the coastal areas of Sonmiani,

Kalmat and Gawatar bay in Balochistan. Sonmiani is the

only place along the coast of Pakistan where three species

of mangroves [Avicennia marina (Forssk.) Vierh,

Ceriops tagal (Perr.) C.B Robinson and Rhizophora mucronata

Lam.] exist naturally. Beside their ecological importance

they have a very significant role in the lives of

coastal dwellers. People who live along the coast utilize

this resource for fuel, construction of houses and fodder.

Different techniques were developed to restore the mangrove

ecosystem through community participation.

shorelines, revetments, and bulkheads where natural recruitment no longer occurs and where conventional planting

methods are ineffective. The principles of REM include the processes of individual seedling isolation within tubular

encasements and adaptation of the juvenile plant to the external environment of the restoration site. The success of

REM results from specifications for encasement preparation, propagule or seedling selection, and positioning of

both encasements and seedlings according to elevation and tidal regimes.

of neotropicaf shorelines has

generated several hypotheses concerning

the factors leading to the zonation of

mangrove species from shore to land.

Zonation has been thought of as an expression

of successional processes that

occur as coastlines extend seaward due to

land building by mangroves, as an expression

of the different physiologicul requirements

of different species, as a function

of propagule size, or as the result of

the geophysical forces that continually

reshape the coastline. This article reviews

the evidence for the various hypotheses,

and comments on the production of mangroves

and their importance in shoreline

management.

estudió la formación de manglar de Avicennia germinans de la Bahía de Chengue (Parque Nacional Natural

Tayrona, Colombia), a partir de la determinación de atributos estructurales y funcionales en tres parcelas de

monitoreo (10 x 10 m) entre junio de 1995 y julio de 1996. Estructuralmente esta formación coincide con las

características generales de bosques de borde de la región Caribe, es decir, árboles pequeños (en términos de

DAP=11.3 cm y altura total=6.3 m) y en altas densidades (16.3 troncos/0.01 ha). Durante el periodo

monitoreado se encontró una baja tasa de mortalidad por parcela (0.7 árboles/año) y se registró un aumento

significativo entre los promedios de la medición inicial y final de la circunferencia a la altura del pecho (y las

variables que se originan de esta medida). Las tasas promedio de crecimiento de altura total, DAPy área basal

por árbol fueron de 26.7 cm/año, 0.17 cm/año y 2.9 cm2/año respectivamente. La hojarasca estuvo conformada

principalmente por hojas (66.1%) y su tasa promedio de producción fue de 43.1 g/m2/mes (5.2 t/ha/año). Se

detectó un patrón temporal de producción de hojarasca y sus componentes asociados a las épocas climáticas del

área, según el cual durante la estación lluviosa son mayores las contribuciones de hojarasca total, hojas y

propágulos, mientras que en la época seca disminuyen los aportes de todos éstos y se incrementa la producción

de flores y ramas. De esta manera los periodos de fructificación y floración se ajustan a un ciclo anual

reproductivo. En general la información obtenida es un nuevo aporte al conocimiento de los manglares de

Chengue y permite concluir que los individuos monitoreados de A. germinans en Chengue contaron con las

condiciones que les permitieron crecer y desarrollarse durante el periodo evaluado.

Structural and functional characteristics of Avicennia germinans mangrove formation of

Chengue bay (Colombian Caribbean).Within the framework of the CARICOMP(Caribbean Coastal Marine

Productivity) monitoring program, a study of the Avicennia germinans mangrove formation of Chengue bay

(Tayrona Natural Park, Colombia) was performed between June 1995 and July 1996, based on the evaluation

of structural and functional characteristics at three monitoring plots (10 x 10 m). The structure of the studied

formation is coincident with that of fringing forests of the Caribbean region in having small trees (dbh=11.3

cm, total height=6.3 m) and high densities (16.3 trunks/0.01 ha). During the monitored period there was a low

mortality rate (0.7 trees/year) and there were significant increases of the circumferences at breast height (as

well as of the variables derived from this measure). Average tree growth rates expressed in height, dbh and basal

area were 26.7 cm/year, 0.17 cm/year and 2.9 cm2/year respectively. Litterfall was composed principally by

leaves (66.1%) and represented a mean production rate of 43.1 g/m2/month (5.2 t/ha/year). There was a

temporal pattern of litterfall production associated with the climatic seasons in the area: during rainy months

the production of total litterfall, leaves and fruits was higher, while during the dry season there was a reduction

of these components and an increase of flowers and wood/twigs. Therefore, flowering and fruit production

periods are fitted to an annual reproductive cycle. In general, the information gathered during this study is a

new contribution to the knowledge of mangrove ecology in Chengue, and showed that the monitored trees had

the conditions to grow and develop during the evaluated period.

revegetation of areas cleared for

groves into saltmarsh environments in the estuaries

agriculture, altered tidal regimes or estuary water

of south-east Australia over the last five decades is

levels, and increases in nutrient levels and

established as a widespread trend through a review

sedimentation.

of a number of independent studies. This process

is occurring in a range of geomorphic settings, and

increases in nutrient levels and sedimentation.

inhabiting estuarine or marine salt marshes in

the tropics and subtropics. As a terrestrial plant community

inhabiting tidally inundated estuarine or marine sediments,

mangroves show considerable adaptation to salinity, waterlogging

and nutrient stress. Thirty-one species of mangrove

and mangrove associates and 23 species of transported

flora, belonging to 25 families at four physiographic

stages of succession of the mangrove plant community at

the terminal part of the Ganges river estuary in India were

examined for arbuscular mycorrhizal (AM) root association.

Dominant members of the mangrove plant community

were all AM, mostly with ‘Paris’ type structures. Many of

the known non-mycotrophic plant families, except the

Cyperaceae, also showed AM association, with intracellular

hyphae and vesicles as the most discernible endophyte

structures. Intensity of AM colonization varied both with

the species and situations of their occurrence, being more

intense and also more extensive in less saline dry ridge

mangroves than in more saline formative and developed

swamp mangroves. Introduced exotic trees on the ridges

and embankments were infected by AM, but less than the

declining mangroves in the same location. Seven species

of AM fungi in common with those of the upstream mesophytic

plants were isolated from root-free rhizosphere soils

of the mangroves, three of which predominated in root

association. These species, individually and as mixtures,

infected roots of salinity tolerant herbs and trees in both

locational silt and upstream alluvial soil with obvious improvements

in their biomass yield and phosphorus nutrition.

AM infective potential of root-free rhizosphere soils

of the dominant members of the mangrove community

were negatively related to salinity level of the sediment

soil of the successional stages. The evidences of AM association

of mangroves and other salt marsh plants obtained

here and those reported elsewhere are discussed.

where density, survival, and growth of juveniles and movement to adult habitat are enhanced over those in

adjoining juvenile habitat types. We reviewed recent literature concerning these four topics and conducted

meta-analyses for density and survival data. Most studies of mangroves as nurseries have addressed only

occurrence or density of fishes or decapods, have not used quantitative sampling methods, and have not

compared alternate habitats. Comparison of nekton densities among alternate habitats suggests that, at times,

lower densities may be typical of mangroves when compared to seagrass, coral reef, marsh, and non-vegetated

habitats. There is little direct consumption of mangrove detritus by nekton. C, N, and S isotope studies

reveal little retention of mangrove production by higher consumers. Densities of prey for transient fishes

and decapods may be greater within mangroves than elsewhere, but there has been no verification that food

availability affects growth or survival. Experimental evidence indicates that mangrove roots and debris

provide refuge for small nekton from predators, thus enhancing overall survival. There is no evidence that

more individuals move to adult habitats from mangroves than from alternate inshore habitats. There is an

obvious need to devise appropriate experiments to test the nursery functions of mangroves. Such data may

then be one more reason to add support for mangrove conservation and preservation.

patterns in above- and belowground biomass, primary

productivity, and growth efficiency along a

tidal gradient in a 4700-ha mangrove forest in the

Dominican Republic. We tested the hypothesis that

spatial patterns of forest structure and growth following

50 years of development were associated

with variations in the soil environment across the

tidal gradient. Twenty-three plots were monitored

from 1994 to 1998. Aboveground biomass and biomass

accumulation were estimated by applying allometric

regression equations derived from dimension

analysis of trees harvested at our study site.

Soil porewater salinity ranged from 5 to 38 g kg -1

across the tidal gradient, and most measurements of

forest biomass and productivity were inversely related

to salinity. Mean standing biomass (233 +/-

16.0 Mg ha -1; range, 123.5–383.5), biomass increment

(9.7 +/- 1.0 Mg ha -1 y -1; range, 3.7–18.1),

annual litterfall rates (11.4 Mg ha -1y r-1; range,

10.2–12.8), leaf area index (LAI) (4.4 m2 m-2;

range, 2.9 –5.6), aboveground net primary productivity

(ANPP) (19.7 Mg ha-1 y -1; range, 15.6–

25.0), and growth efficiency (1.6 +/- 0.2 kg ha -1y -1;

range, 1.0 –3.6) all showed an inverse linear relationship

with salinity. Fine-root biomass (- 2 mm)

(9.7 +/- 1.2 Mg ha -1; range, 2.7–13.8) showed a

weak tendency to increase with salinity, and the

ratio of root to aboveground biomass increased

strongly with salinity. Our results suggest that physiological

stresses associated with salinity, or with

some combination of salinity and other covarying

soil factors, control forest structure and growth

along the tidal gradient. The higher allocation of

carbon to belowground resources in more saline

sites apparently contributed to reductions in ANPP

along the tidal gradient.

in the livelihood of the people of Zanzibar. About

45% of the total population live along the coast and the

majority are involved in the extraction of mangrove

wood products and fishing. Between 80% and 90% of

the local fishing is concentrated in waters close to mangrove-

vegetated areas, creeks and bays. The area under

mangrove vegetation, approximately 20,000 ha, is nevertheless

only 6% of the total land area and necessarily

needs to be used in a sustainable way. Recent efforts to

link research findings from studies of aspects of the biology

and ecology of the mangroves of Zanzibar and the

dependent fisheries, with public awareness programs designed

to educate and sensitize the local community,

have generated a lot of positive interest in participatory

management of the mangrove resources. Awareness of

the ecological links between mangrove ecosystems and

resources such as fish is key to winning management

support. The instillation of a sense of ownership of the

resources by the local population and their legal empowerment

so that they are able to institute and execute control

measures on their resources are also essential components

in the process aimed at achieving full community

support for the sustainable utilization and management

of common resources. Local communities, for example

at Kisakasaka village, are beginning to protect and

to plan better ways of exploiting their mangrove resources.

Based on biological knowledge gleaned through

awareness campaigns, they are carrying out mangrove

restoration programs with positive results. This short

overview discusses some aspects of the biology and ecological

roles of the mangroves of Zanzibar and what has

happened to help change the attitude of the local coastal

community towards the mangrove resources.

subtropical mangrove forest in Moreton Bay, Queensland, Australia, which has been disturbed and

damaged by the construction of a wooden boardwalk and a path. Sections of the forest

immediately adjacent to the boardwalk and path were compared with reference areas to determine

whether changes to the small-scale structural complexity within the forest affected the benthic

fauna. The disturbed area was characterised by having 65–80% fewer pneumatophores, significantly

fewer species and individuals of molluscs, but significantly more species and individuals

of crabs than the reference areas.

The abundance of mangrove pneumatophores and the attached epiphytic algae were manipulated

at two sites to determine whether observed differences in these features could account for the

differences in the assemblage of molluscs in the disturbed area of the forest compared with

reference areas. Five experimental treatments were used: undisturbed controls, pneumatophore

removals (abundance reduced by ca. 65%), epiphytic algal removals (algae removed from ca. 65%

of pneumatophores), pneumatophore disturbance controls and algal disturbance controls. The

experimental reduction of the abundance of mangrove pneumatophores and the associated

epiphytic algae led to significant declines (by as much as 83%) in the number of molluscs utilising

the substratum in the modified plots. There was no significant difference in the abundance of

molluscs in the pneumatophore and algal removal plots suggesting any effect was primarily related

to removal of the epiphytic algae from the surface of the pneumatophores.

The responses by the biota to the changes in the physical environment demonstrate that even

relatively small-scale modifications to the physical structure of subtropical mangrove forests can

lead to significant effects on the diversity and abundance of macrobenthic organisms in these

habitats. Such modifications have the potential to cause cascading effects at higher trophic levels

with a deterioration in the value of these habitats as nursery and feeding grounds. Future efforts at

conservation of these estuarine environments must focus on the prevention or reduction of

modifications to the physical structure and integrity of the system, rather than just on the

prevention of loss of entire patches of habitat.

in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has

produced three Tyrannosaurus-sized theropods and numerous other vertebrate

taxa. Paralititan stromeri is the Þrst tetrapod reported from Bahariya since

1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous

sauropod. The autochthonous scavenged skeleton was preserved in mangrove

deposits, raising the possibility that titanosaurids and their predators habitually

entered such environments.

seed-limited plant populations, seed predation will be

more important than competition in determining the

number of individuals that reach maturity. However,

when plant density is high, competition for microsites

suitable for establishment and growth is expected to have

a relatively greater effect. This dichotomous perspective

does not account for situations in which the risk of seed

predation differs inside versus outside recruitment microsites.

We report the results of a field experiment and

sampling studies that demonstrate such an interaction

between microsite quality and the risk of propagule

predation in mangrove forests on the Caribbean coast of

Panama, where it appears to play a key role in shaping the

demography and dynamics of the mangrove, Rhizophora

mangle. Rhizophora’s water-borne propagules establish

wherever they strand, but long-term sampling revealed

that only those that do so in or near lightning-created

canopy gaps survive and grow to maturity. These

microsites afford better growth conditions than the

surrounding understory and, as importantly, provide a

refuge from predation by the scolytid beetle, Coccotrypes

rhizophorae. This refuge effect was confirmed with a

field experiment in which Rhizophora seedlings were

planted at different positions relative to gap edges, from

5 m inside to 20 m outside the gap. Mortality due to beetle

attack increased linearly from an average of 10% inside a

gap to 72% at 20 m into the forest. The interaction

between canopy disturbance and propagule predation may

be having a large impact on the composition of our study

forests. Being shade-tolerant, Rhizophora seedlings that

escape or survive beetle attack can persist in the

understory for years. However, the high rate of beetleinduced

mortality effectively eliminates the contribution

of advance regeneration by Rhizophora saplings to gap

succession. This may explain why the shade-intolerant

mangrove, Laguncularia racemosa, is able to co-dominate

the canopy in low intertidal forests at our study sites.

observations on its pollination and reproductive biology suggested that this species is pollinator dependent for fruit set, and

bee activities can lead to substantial geitonogamous selfing. Quantitative analysis of the mating system parameters was

performed using progeny arrays assayed for allozyme markers. Multilocus outcrossing rates (tm) were estimated to be 0.697

6 0.091 and 0.797 6 0.062 in two populations. In comparison to other plant species with mixed-mating system, the level

of allozyme variation was very low in the 13 populations sampled along the coastlines of Hong Kong. At the species level,

the proportion of polymorphic loci was 20%, number of alleles per locus was 1.2, and heterozygosity was 0.0362. The total

gene diversity was primarily distributed within populations (HS 5 0.0339), and the coefficient of genetic differentiation

among populations was low (GST 5 0.064). This pattern of population genetic structure suggests that gene flow, primarily

in the form of water-dispersed seedlings in viviparous mangrove species, is not as limited as previously thought. However,

microgeographic pattern in allele frequency at the marker loci could still be detected between the western and eastern coastal

populations.

stands in Hong Kong. The field studies indicate that 43 mangrove stands, excluding Mai Po Nature Reserve, still

remained along the coastline of Hong Kong despite tremendous reclamation and development which occurred in

the past 40 years. Most mangrove stands were found in Deep Bay (western part) and Sai Kung District (eastern

coasts). The total areas occupied by these mangrove stands were 178 ha, varying from a very small stand (with 1–2

mangrove shrubs) to fairly extensive mangroves in Deep Bay (>10 ha). It appeared that mangrove stands located in

Deep Bay area were larger than those in the eastern coasts. Twenty plant species were identified from these stands,

with 13 being exclusive or associate mangrove species. The major constituent species were Kandelia candel,

Aegiceras corniculatum, Excoecaria agallocha and Avicennia marina. Rare species such as Heritiera littoralis

were only found in a few mangrove stands. Out of the 43 remaining mangrove stands, 23 were more worthwhile

for conservation and their plant community structures were further investigated by transect and quadrat analyses.

The importance values (sum of relative abundance, frequency and dominance) show that K. candel was the most

dominant species. Species richness and Simpson’s indices together with tree height, tree density and canopy area

fluctuated significantly between mangrove stands. These values were used to prioritize the conservation potential

of the remaining mangrove stands in Hong Kong.

tropical and subtropical coasts that have been seriously

damaged due to excessive exploitation. The need to

conserve mangroves has been recognized since the

1970s. The degree of mangrove conservation ranges

from rigid ecological conservation (for “posterity”) to

sustainable exploitation (for “prosperity”), dependent on

the needs and requirements of different regions. In Hong

Kong, mangrove resources were rapidly destroyed in the

last decades due to massive reclamation and infra-structural

developments. To conserve the remaining mangroves

in Hong Kong, a comprehensive ecological study

was conducted in 1994–1997 to understand the ecological

characteristics and current status of mangrove

swamps, and 44 remaining swamps were classified into

five categories according to overall conservation values.

The conservation of Hong Kong mangroves is generally

more towards “posterity” with strong emphasis on protecting

biodiversity and maintaining ecological processes.

Different conservation strategies have been recommended

and promoting public awareness is one of the

most important strategies. The possibility of using mangrove

wetlands to remove pollutants appeared to be an

attractive way to increase public awareness and educate

the community. However, more research is needed to

obtain a better understanding of pollutant assimilative

capacity, long-term effects of wastewater-borne pollutants,

costs and life span of such a mangrove wastewater

treatment facility.

their effective conservation and sustainable use. Genetic diversity within and among populations of a

widespread viviparousmangrove Ceriops decandra was determined using inter-simple sequence repeat

(ISSR).Tennaturalpopulationswere collectedfromMalayPeninsulaandNorthAustralia.Atthe species

level, high genetic variationwas detected (P = 72%,HE = 0.253, andI = 0.379).The estimate ofGSTwas

0.882, indicating a high level of genetic differentiation among populations. When populations were

grouped according to geographic regions, i.e., East Malaya, West Malaya, Southmost Malaya, and

North Australia, AMOVA suggested that most of the total variation (87%) was accounted for by

differentiation between regions, with only 4% accounting for variation among populations within

regions, and a further 9% partitioned among individuals within a population. A UPGMA dendrogram

based on genetic distance revealed a deep split between populations from the eastern Indian Ocean

and all others from the western Pacific Ocean, which may result from the historical lowering of sea

level at these regions during the recent Pleistocene glaciations. An understanding of the genetic

structure of C. decandra provides insight for the conservation and management of this species.

tidal, diel and seasonal time-scales. Little effort has, however, been made to quantify accurately the time-scales at which these

properties vary. Many previous studies collected samples from different sites at different times, potentially resulting in the

confounding of spatial and temporal variation. This experiment was designed to determine if time of day or time within the

exposure period had any significant effect on measurements of 7 different properties of sediments. Samples of sediment were

collected using contact cores at the beginning, middle and end of tidal emersion at each of 9 a.m., 12 p.m. and 3 p.m., with two

replicate days of each condition, from mangrove forests fringing Glades Bay, Sydney, Australia. These samples were analysed

for water-content, pigments, carbohydrates, grain-size and loss on ignition (LOI), to determine the potential effects of time of

day and time within the tidal cycle on these properties of the sediments.

Whilst both time of day and time within the tidal cycle were found to occasionally have a significant effect upon the

measured properties, most of the variation occurred among sites and between replicate days of each set of conditions. The

minimal influence of time of day and time within the tidal cycle show that sampling effort should be preferentially placed into

replicating days of sampling and sites because these are the scales with the greatest variation. Differences in the patterns found

also depended on whether the data were expressed as content or concentration, the consequences of which are briefly described.

shrimp aquaculture in the Mekong Delta (Viet Nam) on mangrove ecosystems.

For this exercise we selected two sub-areas (Ca Mau and Tra Vinh provinces)

encompassing a variety of land uses and ecological conditions. Twenty stations

in Tra Vinh and 15 stations in Ca Mau have been surveyed several times from

September 2000 to March 2002. Field investigations included mangrove soils

studies, measurements of pH and salinity of the water, analysis of mangrove

flora, and density and structure of the vegetation. Four Syste`me Probatoire de

l’Observation de la Terre (SPOT) scenes were used for the discrimination of

mangrove types and for the delineation of landscape units. For the first time, five

ecologically distinct landscape classes were identified and delineated. Their

possible links with the farming and yields of high valued species of shrimps,

especially the giant tiger shrimp (Penaeus monodon) destined for export markets,

need further studies. Since 1965, about 30% of mangrove ecosystems have been

lost in Ca Mau Province and more than 30% of present mangroves are replanted

monospecific stands. To the best of our knowledge, this is the first study which

demonstrates that, in spite of deep and ancient man interactions in the Mekong

Delta, five ecologically distinct classes of land use can be defined. Satellite

surveys confirm a clear distribution of landscape units with possible links with

shrimp aquaculture potentialities.

Rhizophora mangle L. up to their first flowering were studied. A continuous production of

flowers and propagules along the year was observed, with a marked seasonality between

the dry and rainy seasons. The annual production of flowers and propagules was of

101.7/m2 and 2.1/m2, respectively. The interval from flowering through maturation of

propagules was 357 (DS 33) days, of which 226 (DS 29) days comprised propagule

development. Out of 2 043 marked flowers, 394 propagules were obtained, the flowering

stage and the dry season being the most critical, during which up to 45% of the flowers

initially formed were lost (Spearman test). Germination took place at 17(DS 5) days after

establishment, with a 96% success, reaching eventually the flowering stage 16% and

28.5% of the plants planted in shade and full sun, respectively (Log-rank test) The first

flowering was recorded at 58 and 73 months respectively. The best development was

reached in plants exposed to full sun. The influence of tides was a decisive factor, while

the appearance of branches and aerial roots determined the survivorship of the plants in

each site.

aperture radar images (ERS 1–2 and Envisat) in humid tropical areas. Effectively, the radar satellite images may be acquired

under most climate conditions, especially in cloudy tropical areas. As case examples, we studied herein French Guiana shoreline

and its fast evolution under the combined influences of sea currents, sediments and swells.We focused on two aspects of French

Guiana littoral evolution: (1) sedimentation and erosion processes linked to mud banks displacements around Kourou City,

and (2) around Iracoubo village. Lastly, we compared this short-term sedimentation balance with long-term data showing

the discrepancies of short- and long-term littoral evolutions on whole French Guiana. To conclude, this work demonstrates the

importance of SAR imagery to provide high-quality and high-frequency update geographic information for coastal management

and littoral hazards especially in such tropical humid and cloudy areas.

of mangrove attributes according to di?erent restoration

criteria at geographically speci®c conditions and at de-

cadal time scales. This model can contribute to the design

and implementation of restoration projects, and also be

used to verify key mechanisms controlling ecosystem at-

tributes during the recovery period. An existing gap model

of mangrove wetlands, FORMAN, was used to simulate

restoration trajectories in one of the largest estuary re-

habilitation projects (128 000 ha) in South America,

Cienaga Grande de Santa Marta, Colombia (CGSM).

Recovery of a disturbed mangrove forest based on simu-

lations of basal area following reductions of salinity to 40

g/kg within 2 yr or 10 yr time periods suggests that in both

cases dominance would reach about 75% of that in the

reference site (80 m2/ha) in 40 yr. Both forests are >80%

dominated by Avicennia, and Laguncularia has greater

basal area than Rhizophora in the remaining structure.

Simulations of forest recovery with a 25 yr target for

salinity reduction show that only about 50% of the basal

area in the reference site is recovered after 40 yr. After 40

yr of recovery, both the 2 and 10 yr salinity targets pro-

duce higher basal area and di?erent patterns of commu-

nity composition (Laguncularia becomes the dominant

species) under enhanced recruitment (planting program)

than observed under more natural recruitment. Ecological

models can be used to establish trajectories of mangrove

response to a variety of initial site conditions at spatially

explicit locations that can improve engineering designs,

project operation, and more clearly de®ne monitoring

programs and natural resource valuation. Modelling

techniques can be used to identify the appropriate spatial

and temporal scales of problems associated with mangrove

restoration projects that could improve our ability to

conserve and manage one of the most valuable forested

wetlands in the tropical coastal zone.

sensitive to increased supplies of nitrogen (N).

The urbanization of coastal watersheds increases

the delivery of N to estuaries, threatening seagrass

habitats; both seagrass production per unit

area and the area of seagrass meadows diminish

as land-derived N loads increase. The damaging

effects of land-derived N loads may be lessened

where there are fringes of coastal wetlands interposed

between land and seagrass meadows. Data

compiled from the literature showed that production

per unit area by seagrasses increased and

losses of seagrass habitat were lower in estuaries

with relatively larger areas of fringing wetlands.

Denitrification and the burial of land-derived N

within fringe wetlands may be sufficient to protect

N-sensitive seagrass habitats from the detrimental

effects of land-derived N. The protection

furnished by fringing wetlands may be overwhelmed

by increases in anthropogenic N loads

in excess of 20–100 kg N ha-1 y -1. The relationships

of land-derived N loadings, fringing coastal

wetlands, and seagrass meadows demonstrate

that different units of the landscape mosaic found

in coastal zones do not exist as separate units, but

instead are coupled and uncoupled by biogeochemical

transformations and transport among

environments.

studied it. This paper examines the effects of small-scale woodcutting on forest structure, composition and regeneration of

mangrove forests in the Philippines. Information for the study was obtained through the application of extensive bio-ecological

assessments of forests and interviews of forest users. Cut mangrove forests were characterized by smaller trees, less basal area

and more canopy gaps. At least two-thirds of all canopy gaps were caused by cutting. In spite of these dramatic structural effects,

there was little demographic evidence to suggest that significant changes to current species composition are occurring, although

this may, in part, reflect that some species have already been eliminated from study areas by past cutting. Among common

species, Rhizophora mucronata was the only one that appeared to be negatively impacted from cutting in terms of its relative

abundance. Although abundance varied, seedlings of all common species measured were taller in canopy and/or expanded gap

compared to understory, with Sonneratia spp. showing the greatest and Avicennia marina the least response. The particular

success of A. marina in cut forests may be explained by the ability of its seedlings to better persist in the understory and thereby

exploit gaps when these are created by cutting. Among common mangrove species, all but R. mucronata appear to be

regenerating well in cut forests: Sonneratia sp., A. marina and R. apiculata regenerate well by coppice regrowth into the

abundant small canopy gaps found in uncut and especially cut forests. Findings from this study highlight the significance of

small-scale cutting disturbance and coppice regeneration as biotic factors in mangrove ecology.

of mangrove forests along the mainland Tanzania coast over the past decade. Mangroves

are recognized as critical coastal habitat requiring protection and special attention.

The Tanzania coastline forms a suitable habitat for establishment of mangrove forests.

Mangrove forests are distributed from Tanga in the north to Mtwara in the south covering

to map mangroves in a study site located at Punta Galeta on the Caribbean

coast of Panama. We hypothesized that spectral separability among mangrove

species would be enhanced by taking the object as the basic spatial unit as

opposed to the pixel. Three different classification methods were investigated:

maximum likelihood classification (MLC) at the pixel level, nearest neighbour

(NN) classification at the object level, and a hybrid classification that integrates

the pixel and object-based methods (MLCNN). Specifically for object

segmentation, which is the key step in object-based classification, we developed

a new method to choose the optimal scale parameter with the aid of

Bhattacharya Distance (BD), a well-known index of class separability in

traditional pixel-based classification. A comparison of BD values at the pixel

level and a series of larger scales not only supported our initial hypothesis, but

also helped us to determine an optimal scale at which the segmented objects have

the potential to achieve the best classification accuracy. Among the three

classification methods, MLCNN achieved the best average accuracy of 91.4%.

The merits and restrictions of pixel-based and object-based classification

methods are discussed.

as surrogates for marine biological diversity in the context of choosing a set of representative

areas for a marine reserve network. Habitat categories were based on interpretation of aerial

photographs and maps, and on local knowledge. Species assemblages were created from

comprehensive survey data on 977 taxa (mainly species), derived from an intensive threeyear

study of a temperate marine embayment, and classified into plant, fish, and invertebrate

assemblages. Reserves were selected using a heuristic iterative algorithm to simulate a

marine reserve network based on 10–80% representation of each surrogate. The effectiveness

of each surrogate was evaluated by comparing the number of taxa that would be

coincidentally included in each simulated reserve for the bay. Areas selected to represent

10% or 20% of the surrogates were best chosen using fish or invertebrate assemblages,

because by spatial coincidence, they included 60–80% of all available taxa. However, areas

selected to represent $40% of the surrogates were generally best derived from habitat

categories, because they included $93% of all available taxa. Plant assemblages were

generally poor surrogates for overall species richness. These findings suggest that habitatlevel

surrogates may be a highly cost-effective method for initial identification of highpriority

areas to manage marine diversity of coastal ecosystems.