Tesi sul tema "Mangrove ecology"

Interactions between species are dynamic and are likely to shift with changes in species ranges due to climate change. With the expansion of new species into incumbent ecosystems a variety of abiotic and biotic factors shape the rate, pattern, and method of invasion. This dissertation utilizes one such boundary of transition, the salt marsh-mangrove ecotone, located in the northern Gulf of Mexico. This dynamic coastal wetland has recently seen the expansion of sub-tropical mangrove species into a previously salt marsh dominated system. This collection of works provides pointed case studies seeking to understand local and patch scale dispersal dynamics, expansion, recruitment, growth, and survival rates along an elevational gradient, and understanding interactions both above- and belowground between mature mangroves and the surround salt marsh. We find that dispersal is overwhelmingly dominated by propagule export, that black mangrove and smooth cordgrass differ in their ability to provide structural provisioning in the short term after restoration, and that mature mangroves have much greater belowground extent than aboveground. By better understanding species-specific interactions at the salt marsh-mangrove ecotone, a greater understanding of future expansion rates can be gained.

Mangrove ecosystems thrive in (sub)tropical, intertidal areas where adaptations

like vivipary and the hydrochorous dispersal of propagules become an absolute

necessity. As propagule dispersal and early growth allow for the replenishment of

existing stands and colonization of new habitats, many authors recognize the

importance of these stages in structuring mangrove populations and communities.

However, when it comes to the actual propagule dispersal and recruitment

mechanisms, there is an apparent lacuna in the current understanding of

mangrove ecology. The period between the mature propagule falling from the

parental mangrove tree and the early growth of the established seedling, under

various possible circumstances, remains in the dark. In this study we focus on this

particular period by investigating both the places where these propagules end up

as the pathways their dispersal units follow. And we go one step further.

Mangrove forests are being destroyed worldwide at a threatening pace despite

their tremendous asset to coastal human communities and associated biological

species. The effect of human-induced (cutting and mangrove conversion to

aquaculture ponds) as well as indirectly and/or ‘naturally’ evolving disturbances

(sea level rise) on propagule hydrochory occupies an important place in this study.

Dispersal of water-buoyant propagules of the family Rhizophoraceae and

Acanthaceae (now including the Avicenniaceae) was studied in Gazi Bay (Kenya),

Galle and the Pambala-Chilaw Lagoon Complex (Sri Lanka). The study sites

differ both in tidal regime and vegetation structure, covering an interesting variety

of ecological settings to examine propagule dispersal. Field data and experiments

ranging from micro/ mesotopographical measurements and successive propagule

counts to hydrodynamic and propagule dispersal experiments were collected or

executed in situ.

Two main methodological approaches were employed. Firstly, the question on

mechanisms of propagule recruitment was addressed by statistically investigating

the effect of microtopography, top soil texture and above-ground-root complexes on

the stranding and self-planting of propagules (Chapter 2&3). Afterwards,

suitability maps were created using Geographical Information Systems (GIS) to

assess whether a particular mangrove stand has the ability to succesfully

rejuvenate. Furthermore, the effect of degradation (tree cutting) (Chapter 2&3),

sea level rise (Chapter 2&4) and microtopography-altering burrowing activities of

the mangrove mud lobster Thalassina anomala (Chapter 3), was incoporated in the

GIS-analyses. Secondly, the combined set-up of hydrodynamic modelling and

ecological dispersal modelling was developed to simulate propagule dispersal

pathways influenced by dispersal vectors (tidal flow, fresh water discharge, wind),

trapping agents (retention by vegetation or aerial root complexes) and seed

characteristics (buoyancy, obligated dispersal period) (Chapter 5&6). This type of

approach provided the possibility to explore propagule dispersal within its

ecological context, but was also applied to an implication of shrimp pond area

restoration (Pambala-Chilaw Lagoon Complex, Sri Lanka) (Chapter 5) and to

evaluate changes in propagule dispersal when sea level rises (Gazi Bay, Kenya)

(Chapter 6).

The main findings regarding propagule recruitment indicate that propagules are

not distributed equally or randomly within a mangrove stand, yet species-specific

distribution for anchorage occurs. Characteristics of the environment

(microtopography, top soil texture and above-ground root complex) influence

propagule recruitment in a way that complex root systems (e.g. pencil roots and

prop roots) facilitate the entanglement of dispersal units and a more compact soil

texture (like clay and silt) and a predominant flat topography creates suitable

areas for stranding and self-planting of propagules. This combines effects of

existing vegetation and abiotic factors on mangrove propagule establishment.

Since propagule dispersal is not solely determined by species-specific propagule

characteristics (e.g. buoyancy, longevity, etc.), I emphasize that propagule sorting

by hydrochory has to be viewed within its ecological context. Propagule retention

by vegetation and wind as a dispersal vector, deserve a prominent role in studies

on propagule dispersal. The significance of dense vegetation obstructing long

distance dispersal (LDD in its definition of this work), mainly in inner mangrove

zones, supports our main finding that propagule dispersal is largely a short

distance phenomenon. ‘Largely’ is here understood as quantitatively, not

excluding epic colonization events of rare but important nature.

In accordance with the Tidal Sorting Hypothesis (TSH) of Rabinowitz (1978a),

smaller, oval-shaped propagules were found to disperse over larger distances than

bigger, torpedo-shaped propagules. We can however not fully support the TSH

because (1) these differences are no longer valid when comparing between torpedoshaped

propagules of different sizes and (2) propagule dispersal is not always

directed towards areas more inland, but can be strongly concentrated towards the

edges of lagoons and channels

Anthropogenic pressure on mangrove ecosystems, more specifically clear-felling or

mangrove conversion to aquaculture ponds, imposes limitations on propagule

recruitment due to reduced propagule availability and a decrease in suitable

stranding areas where the architecture of certain root complexes, like prop roots

and pencil roots, function as propagule traps. These types of pressure appear to

have more severe consequences on propagule dispersal than the effect of sea level

rise on mangroves. Mangrove forests, which are not situated in an obviously

vulnerable setting, can be resilient to a relative rise in sea level if a landward shift

of vegetation assemblages and successful early colonization is not obstructed by

human-induced pressures. Also, and this renders mangrove forests vulnerable in

spite of their intrinsic resilience, when the ‘capital’ of forest is severely reduced or

impoverished as happens extensively worldwide, the ‘interest’ on this capital,

understood as propagule availability, delivery and trapping, will not allow them to

efficiently cope with sea level rise, putting sustainability of mangrove ecosystem

services and goods at risk.

In a larger framework of mangrove vegetation dynamics, knowledge on propagule

dispersal will benefit management strategies for the conservation of mangroves

worldwide, besides its fundamental interest to fully fathom the ecology of this

particular marine-terrestrial ecotone formation.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Patterns of distribution of crabs inhabiting burrows in three temperate mangrove swamps near Sydney, New South Wales, were described. Heloeoius cordiformis (an ocypodid) did not exhibit a consistent pattern of distribution among three tidal zones, but was always associated with well— drained mounds of substratum within zones. Paragrapsus laevis (a grapsid) tended to be most abundant in the lower two zones on the shore and usually inhabited burrows in the moist or submerged flats between mounds. Sesarma erythrodactyla (a grapsid) was distributed fairly evenly among the three tidal zones and also between mounds and flats. H. cordiformis hibernated in burrows from June through August or September. Overall abundances also varied seasonally, but trends were inconsistent among the three swamps sampled.

Increasing urbanisation of coastal areas is placing unprecedented pressure on estuarine environments. Impacts associated with urbanisation can alter the health of estuarine ecosystems, reducing their capacity to provide valuable ecosystem services. In order protect these environments, relationships between estuarine health and urbanisation should be understood and applied to sustainable urban planning in coastal areas. Responses measured in estuarine biota offer much potential for providing pragmatic and sensitive means for the detection of urban impacts in estuaries. I assessed the responses of estuarine biota to increasing levels of urbanisation in the rapidly developing coastal region of southeast Queensland, Australia. I measured a suite of biotic indicators, namely: the δ15N of mangroves and crabs as a tracer for urban N sources, sediment chlorophyll a concentration (Chl a) as an estimate of the biomass of microphytobenthos (MPB), and a condition index in crabs, measured as the hepatosomatic index (HI). Urbanisation was estimated as the percentage of catchment covered by impervious surfaces (impervious cover, IC). Increases in impervious surfaces such as roads, footpaths and car parks are closely linked to urbanisation. These surfaces concentrate and convey pollutants generated from urban activities into coastal waterways and estuaries, thus making IC a useful indicator of urban impact.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

South Australian mangroves consist of only one single species Avicennia marina (Fosk.) Vierh.var australasica (Walp) Moldenke, 1960. They are distributed discontinuously within St. Vincent Gulf and Spencer Gulf and provide significant valuable habitat both in economical and ecological terms. The Fisheries Act 1971-1982 protected the existence of mangroves and the Harbour Act 1936-1981 controlled removal of mangrove areas in coastal development. To date very few ecological studies have been conducted in the South Australian mangroves, particularly on the infaunal organisms that have an important role in maintaining the ecological dynamic within the estuaries systems. As this is the first study on infaunal mangrove communities in the inverse estuaries of South Australia, there was no prior data for ecological comparison. The study was conducted at three mangroves location (Garden Island, Middle Beach and Saint Kilda) close to Adelaide in May 2000 and 2001. Overall the study has reported that the infaunal mangrove assemblages of South Australian mangroves were comparable to other temperate mangroves. The infaunal communities were characterised by lower diversity and abundance compared to the tropical or subtropical mangroves. The infaunal zonation related to the tidal gradient and habitat variation was detected. Most infauna organisms occupied the surface layers and substantially decreased towards the deeper layers. The study also suggested that sediment structure of mangrove systems were complex and infaunal communities responded differently to the change of environmental conditions both in small scale and larger scale. Thus, assessing the infaunal communities structure in mangrove systems should be based on ecological characteristics rather than geographical positions. The examination of dominant polychaetes families showed that different species have different responses to the environmental cues within mangrove systems. The study did not find that any polychaete species was restricted to mangroves only as they all were also found in the habitat adjacent mangrove forest.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2003.

In South Africa mangrove forests are located in estuaries from Kosi Bay in KwaZulu-Natal (KZN) to Nahoon Estuary in the Eastern Cape. The aims of this study were to determine the present state of mangroves in KwaZulu-Natal, by assessing the current population structure, the changes in cover over time and associated anthropogenic pressures. A second objective of this study was to determine the effect of harvesting on the population structure and sediment characteristics in the Mngazana mangrove forest. To determine if harvesting was sustainable at Mngazana Estuary; the growth and mortality rates and associated growth conditions were measured. Finally by using population modelling sustainable harvesting limits were determined by predicting the change in population structure over time. The study focussed on the KwaZulu-Natal province as a fairly recent study addressed mangrove distribution and status in the Eastern Cape Province. A historical assessment of all mangroves forests in KwaZulu-Natal (KZN) revealed that the potential threats to mangroves in South Africa include; wood harvesting, altered water flow patterns coupled with salinity changes, prolonged closed-mouth conditions and subsequent changes to the intertidal habitat. As a result mangroves were completely lost from eleven estuaries in KZN between 1982 and 1999 and a further two estuaries by 2006. Mangroves only occurred in those estuaries where the mouth was open for more than 56 percent of the time with the exception of St Lucia, where the mouth has been closed for longer but the mangrove communities have persisted because the roots of the trees were not submerged. All mangrove forests in KZN were regenerating in terms of population structure as they had reverse J-shaped population curves as well as high adult: seedling ratios. Kosi Bay and Mhlathuze Estuary were two of the larger forests that showed signs of harvesting (presence of tree or branch stumps), but the greatest threat to smaller estuaries seems to be altered water flow patterns due to freshwater abstraction in the catchments and the change of land use from natural vegetation to sugar-cane plantations. These threats affect the hydrology of estuaries and the sediment characteristics (particle size, redox, pH, salinity, temperature) of the mangrove forests. The environmental conditions under which the mangrove forests currently exist were determined for five species. Lumnitzera racemosa and Ceriops tagal exhibited a narrow range of conditions as these species are only found at Kosi Bay, while Avicennia marina, Bruguiera gymnorrhiza and Rhizophora mucronata were found to exist under a wider range of conditions. The growth rate and response to environmental conditions of the three dominant species were important to determine as these species are impacted by harvesting. Mangrove growth rates were measured at Mngazana Estuary in the Eastern Cape, the third largest mangrove forest in South Africa. Areas of this estuary where mangroves harvesting has occurred, show significant differences in sediment characteristics as well as changes in population structure in harvested compared to non harvested sites. The growth rate (in terms of height) of Avicennia marina individuals increased from seedlings (0.31 cm month-1) to adults (1.2 cm month-1), while the growth of Bruguiera gymnorrhiza stabilised from a height of 150 cm at 0.65 cm month-1. The growth of Rhizophora mucronata peaked at 0.72 cm month-1 (height 151-250 cm) and then decreased to 0.4 cm month-1 for taller individuals. Increases in diameter at breast height (DBH) ranged between 0.7 and 2.3 mm month-1 for all species. Some environmental variables were found to be important drivers of growth and mortality of individuals less then 150 cm. A decrease in sediment pH significantly increased the mortality of Avicennia marina seedlings (0-50 cm) (r = - 0.71, p<0.05) and significantly decreased the growth of Rhizophora mucronata and Bruguiera gymnorrhiza seedlings (r = -0.8, r = 0.52 – p < 0.05 respectively). At Mngazana Estuary, mortality of this species showed a positive correlation with sediment moisture content indicating that this species prefers drier conditions. The density of Rhizophora mucronata was significantly correlated to porewater temperature in Northern KZN as was the growth of adult (>300 cm) Rhizophora trees at Mngazana Estuary. Mortality of Avicennia marina individuals (51-150 cm) was related to tree density indicating intraspecific competition and self thinning. Selective harvesting of particular size classes of Rhizophora mucronata was recorded when comparing length of harvested poles (~301 cm) and the size class distribution of individuals. Taking into account the differences in growth rate for each size class for this species it will take approximately 13 years to attain a height of 390 cm which is the height at which trees are selected for harvesting at this estuary. This is 2.6 times slower than those individuals growing in Kenya. The feasibility of harvesting is dependent on the growth rate of younger size classes to replace harvested trees as well as the rate of natural recruitment feeding into the population. Different harvesting intensity scenarios tested within a matrix model framework showed that limits should be set at 5 percent trees ha-1 year-1 to maintain seedling density at > 5 000 ha-1 for R. mucronata. However harvesting of Bruguiera gymnorrhiza should be stopped due to the low density of this species at Mngazana Estuary. Harvesting of the tallest trees of Avicennia marina can be maintained at levels less than 10 percent ha-1 year-1. Effective management of mangrove forests in South African is important to maintain the current state, function and diversity of these ecosystems. Management recommendations should begin with determining the freshwater requirements of the estuaries to maintain the mouth dynamics and biotic communities and deter the harvesting of (whole) adult trees particularly those species that do not coppice. Further management is needed to ensure that forests are cleared of pollutants (plastic and industrial), and any further developments near the mangroves should be minimized.

Mangrove habitats are considered as the ideal fish nursery as they are known to increase the growth and survival of juvenile fishes by providing enhanced food availability and protection. However, most studies have focused on tropical mangroves with a few recent warm temperate studies finding conflicting results. Furthermore, the nursery value of South African mangroves to fishes remain understudied in subtropical areas, while warm temperate mangroves are yet to be evaluated. This study aimed to assess whether mangrove presence leads to any advantage to the larvae of an important estuarine resident fish species, Gilchristella aestuaria, by comparing the food patch quality of South African warm temperate mangrove and non-mangrove estuaries. Results indicate that larvae fed primarily on the dominant prey species, Pseudodiaptomus hessei, Paracrtia longipatella, and Acartiella natalensis. However, postflexion larvae consumed more of the larger species, P. hessei, within the two mangrove estuaries (16.09 %V in Nahoon and 13.79 %V in Xhora) than the two nonmangrove estuaries (12.20 %V in Gonubie and 7.05 %V in Qora), despite other prey species occurring at similar densities. Results indicate that mangrove habitats acted as sediment sinks, slightly reducing the turbidity of these estuaries which resulted in postflexion larvae actively selecting larger, more nutritious prey, which in turn, significantly increased their individual instantaneous growth rates (0.11 ± 0.21 Gi) when compared to postflexion larvae in non-mangrove estuaries (0.09 ± 0.12 Gi). This study found that mangrove presence was significantly related to postflexion larval densities when coupled with abiotic (such as temperature and turbidity) and biotic factors (such as predator-prey interactions). Understanding the spatial and temporal dynamics, predator-prey interactions as well as the growth and survival of G. aestuaria is particularly important as they are key zooplanktivores that are prey to other species in estuarine food webs.

I compared wading bird foraging ecology in commercial shrimp ponds and natural mangrove mudflats in the Muisne River Estuary in northwest Ecuador. I estimated foraging habitat suitability by observing the foraging efficiency, diet, and behavior of great (Ardea alba) and snowy (Egretta thula) egrets, censusing birds, and measuring prey availability (i.e. prey density, standing crop, water depth, and diversity). Great egrets had greater foraging efficiency in shrimp ponds, while snowy egret foraging efficiency was greater on mudflats. Over 85% of prey items in snowy egret boluses were from shrimp ponds. Mean density, standing crop, length, and mass of prey items was significantly greater in shrimp ponds, but availability was limited by water depth and diversity. Great and snowy egrets utilized shrimp ponds as their primary foraging grounds, while all other diurnal wading bird species foraged primarily on mudflats, where the diversity of wading birds and their prey was greatest.

The ecology of mangrove forests on Potential Acid Sulphate soils at Bintuni Bay (132° 55' - 134° 02' E, and 2° 02' - 2° 97' S), Irian Jaya, Indonesia was studied. The annual rainfall is 3000mm and there is mixed semi-diurnal tide of 1-5.6m amplitude. The water has a varying salinity of 0-27%. Forest structure was studied in plots of 10m x 10m along three transects across Sikoroti Island and in three 50m x 50m plots in mixed Rhizophora - Bruguiera forest. All trees > 10cm trunk diameter were enumerated, measured and identified. Of the nine tree species, Rhizophora apiculata was the most dominant, followed by Bruguiera gymnorrhiza and Ceriops decandra. There was good regeneration seven years after clear-felling in plots on Amutu Besar and Amutu Kecil Islands. Small litterfall production, measured using ten 1m x 1m litter traps in each of the three 50m x 50m plots, was 11.09 t ha-1 y-1, and greatest during the wet season (December, 1.29 t ha-1 ) and least during the dry season (July, 0.61 t ha-1). The annual litterfall mineral element accession was (kg ha-1 y-1): N 240.4, P 6.1, K 43.2, Na 136.2, Ca 204.4 and Mg 48.7. Leaf decomposition of five species was studied in litterbags on the forest floor under trees of the same species. Sonneratia alba decomposed quickly with a half-life of 24 days, and Bruguiera parviflora was the slowest with a halflife of 124 days. Decomposition rates of all species followed a single exponential decay model. Leaf herbivory of young stands of Rhizophora apiculata and Bruguiera gymnorrhiza was significantly different among sites, species, plant height and leaf-age. Seed predation on six species was studied in three different sites. Twenty propagules of each species were secured by string in each of six 10m x 10m sub-plots within each of five 10m x 60m plots. On average 62.1% of the seeds were dead after 36 d. Predation was higher in the lower intertidal zone, and Avicennia alba and Bruguiera parviflora were the most predated. The results suggested that the Bintuni Bay mangroves can be sustainably managed but the best silvicultural system needs to be determined.

Thesis (M. Sc.) (Hons) -- University of Western Sydney, 2003.
"Submitted in accordance with guidelines for the Degree of Master of Science (Hons), College of Science, Technology and the Environment, University of Western Sydney, Hawkesbury, Richmond NSW, Australia, March 2003." Includes bibliography : leaves 229 - 254, and appendices.

Mangroves in South Africa are prone to anthropogenic pressures such as browsing and trampling by livestock and by natural disturbances such as drought and floods. These mangroves exist at one of the most southerly limits in the world providing a unique opportunity to study recovery and resilience to change. This study used long term data at three South African study sites located in the subtropical (St Lucia Estuary) and warm temperate regions (Nxaxo and Kobonqaba estuaries) to compare mangrove growth rate, population structure and responses to disturbance. The first objective was investigated at St Lucia Estuary where site specific or microhabitat differences were measured to assess the influence of these on mangrove growth and population structure. It was suggested that site - specific variability would ensure mangrove survival and analysis showed that seedlings were present at different sites in different years. There was always some recruitment but often little survival to the next size class. Over time seedling numbers were quite variable and self – thinning of adults was evident. The second objective was to identify the environmental factors influencing population density and growth. Results showed that sediment moisture and salinity influenced seedling and adult density due to fluctuations in estuary water level. Mangrove growth rates for Avicennia marina in terms of height was faster (40 – 75 cm yr-1 ) at Site 1 where conditions were waterlogged and moderately saline and slower (5 – 25 cm yr1 ) in dry and hypersaline conditions at Site 4. Overall mangroves at St Lucia have shown persistence through drought and fluctuations in environmental conditions however resilience may be hindered at sites that are subjected to partially flooding and prolonged waterlogging. The second site was Nxaxo Estuary in the Eastern Cape where cattle exclusion plots (nonbrowsed) and control plots (browsed) were used to assess the recovery of A. marina trees from cattle browsing. Trees in the browsed plots showed no vertical growth while trees in the non-browsed plots grew significantly faster (5.4 ± 0.5 cm yr-1). When cattle were prevented from entering the mangrove area, the trees recovered fairly quickly and within 3 years growth was similar in both the non – browsed (17.9 ± 3.2 cm yr -1) and browsed plots (18 ± 1.6 cm yr -1). Lastly, mangrove recovery was investigated at Kobonqaba Estuary where long-term closure of the mouth to the sea resulted in high water levels, inundation of pneumatophores and die-back of the majority of the mangroves. This study measured the recovery of the mangroves by assessing changes in vegetation cover and sediment characteristics along transects. High initial porewater nutrient concentrations promoted salt marsh growth and plants increased average cover from 0% in 2011 to 18.9% (2013) and 50% in 2015. The total number of A. marina individuals increased from only seven to 27 individuals over four years. Salt marsh competition and facilitation will likely influence mangrove recovery in the future. Overall it was concluded that when a short term pressure (cattle browsing) is alleviated, mangrove forests even at warm temperate sites are able to recovery rapidly by increasing growth and seedling establishment. However, mangroves in the subtropical sites show more resilience and recovery potential to long term pressures such as fluctuating environmental conditions because of faster growth rates.

The value of mangrove habitats as fish nurseries was assessed by comparing communities of early stage and juvenile fishes between estuaries with and without mangroves. Early stage fishes were sampled using boat-based plankton towing while juveniles were sampled by seine netting. Sampling took place at five sites spaced 1 km apart starting near the estuary mouth in four estuaries along the temperate coastline of the Eastern Cape Province of South Africa. Four estuaries were selected based on shared similarities which included catchment area, estuarine area and shared habitats barring the presence of mangroves which occupied the river margins of two systems. Results revealed that early stage and juvenile fish communities (both marine- and estuary-spawned) were similar between systems with and without mangrove habitats. Differences in fish communities among estuaries were rather attributed to axial salinity gradients associated with greater freshwater input, while season and temperature produced significant variances in fish densities with Generalised Additive Models revealing responses of communities to these variables. A common estuarine-dependent fish, Rhabdosargus holubi (Family Sparidae), was further investigated to determine habitat use, residency and dietary patterns in different mangrove habitats. High habitat residency in this species was revealed during a short-term tagging study using Visible Implant Elastomer tags and long-term isotope analysis in juveniles sampled from two contrasting mangrove habitats. A wider feeding niche was observed in an eelgrass-red mangrove connected habitat when compared with more exposed white mangrove areas. Low dependence on mangrove habitats in temperate estuaries is likely due to their tidally dominated inundation and limited refuge potential due to smaller area coverage by mangroves in temperate estuaries. Relatively lower primary productivity in warm temperate mangrove areas, relative to their tropical counterparts, provides no significant feeding advantage or refuge opportunities relative to other available habitats in these estuaries. Warm temperate estuaries, which are both spatially and temporally highly variable, instead host species which are habitat generalists, able to capitalise on these highly dynamic environments.

There are large gaps in the coverage of critical ecological processes related to the movement of individuals or genes (i.e. dispersal), which is critical for determining the spread and persistence of populations across space. In this dissertation we investigate understudied but important aspects of the dispersal process in mangroves, with as the main objective the reduction of parameter and model uncertainty. Models rarely incorporate realism and complexity at the level of emigration, transfer and immigration phases, hampering reliable predictions of dispersal patterns and long-term population dynamics under different climate change scenarios.

Mangrove ecosystems function at the edge of land and sea, often covering large intertidal areas along (sub)tropical coastal regions worldwide. Mangroves can live in these highly dynamic and demanding environmental conditions via a series of remarkable adaptations. They produce buoyant seeds and fruits (propagules) that disperse at the ocean surface (i.e. hydrochory - see cover image).

Despite their ecological and economical value, about 40 % of original mangroves have been lost worldwide during the last 50 years due to excessive exploitation and development. Deforestation, degradation and conversion to other land uses like intensive shrimp farming and agriculture have reduced and fragmented these ecosystems at an alarming rate. Climate change, probably most pronouncedly via changes in sea level, poses another important threat.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

The saltwater mosquito, Aedes vigilax (Skuse), is a major vector of Ross River virus and Barmah Forest virus across sub-tropical and tropical Australia, and poses a significant human health risk, particularly in densely populated areas such as South East Queensland and Northern New South Wales regions of eastern Australia. The insect uses saltmarsh and mangrove basin forests as oviposition and larval habitats, and various mosquito control methods exist that target larval stages. Fish, acting as predators of larvae, have routinely been used as a component of mosquito control strategies worldwide. If managed appropriately biological control using fish can be effective, but if mismanaged, biological control can have serious environmental consequences. For example, the release of the Mosquitofish (Gambusia holbrooki (Girard)) for mosquito control in Australian waterways has caused significant ecological damage; G. holbrooki is now a major invasive pest. Nonetheless, mosquito control strategies that include the use of native fish populations in the strategy may be more effective for controlling mosquitoes in mangrove basins than those that do not include native fish. However, little is known of fish populations (both exotic and native) within mangrove basins, and the impact these fish do, and could have on mosquito populations. This research examines the relationship between resident fish and saltwater mosquitoes in eastern Australian mangrove basin forests. It focussed specifically on two mangrove basin sites in the South East Queensland/Northern New South Wales region, and evaluates the potential of resident mangrove basin fish as biological control agents in mangrove ecosystems.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Meiofauna are ubiquitous but poorly-studied components of soft-bottom marine communities around the world, including mangroves. However, information on the ecological role of the meiofauna in subtropical intertidal habitats is scarce compared to knowledge of the benthic macrofauna. The dynamic environmental conditions and heterogeneous sediments of mangroves present challenges to understanding the structure of mangrove meiofaunal assemblages at various spatial and temporal scales. This study was designed to elucidate the ecological role of the meiofauna in mangroves by studying their three main ecological elements: 1) assemblages structure; 2) top-down interaction with macrofauna; and 3) bottom-up interaction in terms of nutrient utilisation. Firstly, how meiofaunal assemblage respond to estuarine sediment conditions was described by analysing the assemblages associated with different mangrove species (Avicennia marina, Rhizophora stylosa and Aegiceras corniculatum) at three locations in sub-tropical Southeast Queensland, Australia. Secondly, the significance and nature of top-down control on the density of meiofauna based on their interactions with deposit- feeding crabs was investigated in a mangrove and the adjoining sandflat.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Sesarmid crabs have important ecological roles in the mangroves of the Indo-west-Pacific biogeographic region. By processing large amount of leaf litter, these crabs retain organic matter in the mangroves, increase the rate of mineralisation, and fuel additional trophic links with the processed material. However, the dietary composition of the mangrove sesarmids is still a controversy. Gut content analyses suggest a dominant contribution of mangrove leaf litter in the crab diet but stable isotope data seem to support the assimilation of organic matter derived from the microphytobenthos but not mangrove litter. In addition, ability of the sesarmid crabs to obtain sufficient nutrition from mangrove litter, which is rich in structural carbon (cellulose) but poor in other nutrients such as nitrogen, has been questioned. The over-arching goal of this thesis was to fill these gaps of knowledge in detritivory of the mangrove sesarmids, using Parasesarma erythodactyla (Hess, 1865), the dominant shredder in sub-tropical Australian mangroves, as an animal model.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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The meiofauna of a mangrove forest in the River Barwon estuary was studied by means of surveys and field experiments. Distinctive assemblages of meiofauna were described from the sediment and pneumatophores of the ecosystem. Fine resolution of phytal habitats was demonstrated, and particular assemblages of meiofauna were characteristic within habitat provided by dominant epibionts. Distribution of the meiofauna within leaf litter revealed high turnover rates of nematodes, and some factors controlling detrital assemblages were assessed. The vertical profile of sedimentary meiofauna was examined, and changes in abundance were related to the tychopelagic habit of many taxa at high tide. Dispersal within the water column was confirmed by pelagic trapping, and colonisation of mimic pneumatophores was investigated. The amount of algal cover, effects of grazing by gastropods, and rugosity of the colonised surface were shown to influence meiofauna colonisation of mimic pneumatophores. Establishment and persistence of patchy distributions of meiofauna at scales of less than 10 m in an intertidal environment was demonstrated, and it was concluded that this was due to the dynamic nature of assemblages rather than their integrity.

Estuarine habitats along the temperate south-eastern shores of Australia are generally made up of salt marsh, mangrove forests and seagrass beds. In urban areas these habitats have been progressively fragmented as a result of population increase and industrial expansion. Salt marshes in particular have been vulnerable to urban expansion and reclamation because of their close proximity to densely populated areas, while mangrove forests have been less often reclaimed because of frequent tidal inundation. The effect of reclamation of salt marshes on the biotic assemblages and functioning of mangrove forests with an adjacent salt marsh, park or bund wall was examined at nine separate locations on the Parramatta River, Sydney NSW. A mensurative approach was used to describe the patterns of distribution and abundance of macro fauna at several temporal and spatial scales. The implications for management are that salt marshes are an integral part of estuaries, and smaller patches of salt marsh are just as important as larger patches in maintaining the diversity of faunal assemblages and ecosystem functioning in mangrove forests in urban areas
Master of Science (Hons)

Ammonia/ammonium-oxidizing prokaryotes (AOPs) play a crucial role in nitrogen transformation in the natural ecosystems including mangrove wetlands. The objectives of the present study were to investigate the spatial and temporal distribution of AOPs in the mangrove wetland sediments in subtropical Hong Kong and their ecophysiology. When AOP communities and abundances in a natural coastal mangrove wetland and a constructed freshwater wetland were compared, the constructed freshwater wetland contained a broader range of phylotypes, higher diversity, more complex community structures, and more uneven abundances of AOPs than the mangrove wetland. Typha angustifolia affected the community structures of all AOPs and enhanced their abundances in the rhizosphere. Both Phragmites australis and Cyperus malaccensis showed some effects on the community structures of ammonia-oxidizing bacteria (AOB), but little effects on those of anaerobic ammonium oxidizing (anammox) bacteria or ammonia-oxidizing archaea (AOA). Kandelia obovata had no detectable effect on any group of the AOPs due to their smaller size. AOPs in oxic and anoxic sediments of a protected mangrove wetland were investigated in both winter and summer. Seasonality had little effect on community structure and abundance of anammox bacteria. AOA community structures were stable between the two seasons, but AOA abundance was significantly higher in winter than summer. The community structures of AOB were different between winter and summer, but the abundance in winter was apparently higher than that in summer. Sediment type had a noticeable influence on community structure and abundance of anammox bacteria. No apparent difference in AOA community structures between the different types of sediments in winter was observed, but the oxic sediments showed obviously different AOA community structures from anoxic sediments in summer. Sediment type had little effect on AOB community structures, but AOB abundance in oxic sediments was obviously lower than anoxic ones in both seasons. Addition of acetate or leaf litter into sediment inhibited the growth of anammox bacteria in laboratory incubation. The inhibition of anammox bacteria by acetate was more pronounced than by leaves. Acetate and leaf litter did not affect AOA community structures, but promoted their growth. Both acetate and leaf litter affected the AOB community structures and promoted their growth in the early phase of the incubation. The promoting effects by leaf litter were more obvious than by acetate. Allylthiourea effectively inhibited the growth of both AOA and AOB in laboratory incubation, but only slightly for anammox bacteria. Acidic condition altered AOB community structure, but affected anammox bacteria and AOA slightly. Alkaline condition strongly affected community structures of anammox bacteria and AOA, but slightly for AOB. Alkaline condition inhibited the growth of anammox bacteria, but promoted AOA and AOB slightly. Increase in salinity resulted in higher diversity of anammox bacteria, and AOA and AOB might have species specific preference for salinity. High salinity promoted anammox bacteria growth; inhibited AOA for 5-10 days, but promoted them afterward; and promoted AOB. Totally, this study revealed new and specific information on the spatial and temporal distribution of AOPs in mangrove wetland and factors affecting their ecophysiology.
published_or_final_version
Biological Sciences
Doctoral
Doctor of Philosophy

Macrozoobenthic community structure and composition was investigated along a subtidal-intertidal gradient in the Mngazana Estuary. Six transects were sampled between the spring high water mark (HWST) and the bottom of the river channel in the lower estuary. Fifteen replicate samples were collected along each transect using a Van Veen type grab (211 cm2 bite) during each of three sampling sessions. Samples were sieved through a 500 μm mesh bag and the invertebrates stored in bottles for further analysis in the laboratory. Additional grab samples were collected for sediment particle size analysis and organic matter. Physical variables measured at each transect included: salinity, temperature, dissolved oxygen, depth, pH, percentage mud, organic content and turbidity. Sediment compactness was measured at all intertidal transects and additional sediment samples were collected at mid shore and high shore transects for percentage water content analysis. A total of 104 species were recorded along the intertidal-subtidal gradient in the sampling area. Species richness was higher in the subtidal zone compared to the intertidal zone and polychaetes numerically dominated the macrozoobenthic community at most transects, during all three sessions. At high shore transects the community was characterised by having fewer species, consisting mostly of brachyurans, polychaetes and gastropods. Shannon diversity index (H’) was generally higher for subtidal transects (x¯ = 2.3; range: 2.8 to 1) than for intertidal transects (x¯ = 1.4; range: 2.2 to 0.6) indicating that the distribution of individuals among species in the intertidal zone experienced greater variability. Results for Hill’s numbers followed the same trend as Shannon diversity with subtidal communities mostly consisting of abundant species followed by very abundant species. Intertidal communities generally exhibited lower numbers of abundant and very abundant species. Sedimentary characteristics played a major role in structuring benthic communities in comparison to other physico-chemical variables. Organic content and mud content of the substrate were identified as important factors influencing community patterns observed along the subtidal-intertidal gradient. In addition, sediment compactness and water content of the substrate was found to influence intertidal community structure. Subtidal community structure possibly had a greater dependence on seasonal variations in abiotic and/or biotic factors. Cluster dendrograms used in conjunction with MDS ordination mapping revealed that macrozoobenthic communities were generally distinct between high shore intertidal transects iii and subtidal transects. Most species exhibited a broad spatial distribution along the subtidal-intertidal gradient with mid and high shore transects being the exception. Most species also exhibited marked shifts in abundance and this was especially noticeable at the transition between the subtidal and intertidal zone. Two polychaete species, Prionospio sexoculata and Capitella capitata, were very abundant species and featured amongst the most numerically dominant species collected during each sampling session.

Crabs are conspicuous inhabitants of temperate salt marshes and tropical mangroves and interact with their environment through several processes. However, detailed information on crab community processes is absent for most South African estuaries and nearshore coastal regions. This study evaluated the primary producers supporting crab species in the salt marsh dominated Swartkops estuary and the mangrove Mngazana estuary. Various methods estimating crab abundances were also assessed in different microhabitats and the larval distribution of crabs in the coastal zone was also investigated. Various methods for estimating crab abundance have been employed in the past, each with its inherent biases. The microhabitat of a mangrove forest in Australia was structurally altered by the manipulation of the litter, pneumatophores and the associated algae. These alterations did not affect the behavioural activity or the numbers of crabs recorded in any of the experimental treatments by either visual counts or pitfall traps. However, the number of crabs caught in the pitfall traps differed between the sites. Species-specific behaviour which was not investigated in this study may bias crab abundance estimates when using pitfall traps and therefore requires further investigation. Benthic consumers inhabiting shallow coastal environments may ultimately have the origin of their nutrition in a number of possible sources. Isotopic and gut content analysis of Thalamita crenata and juvenile Scylla serrata in the Mngazana estuary in South Africa revealed that these two portunids are able to share a habitat by resource partitioning. Differences were noted for species-specific utilization of primary producers not only between seasons within a site, but also between sites. This highlighted the use of locally produced primary producers sustaining food webs in estuaries. Mangrove production in the Mngazana estuary is very important and contributes to most of the carbon in the underlying sediments in the mangrove forest. However, the relatively large number of species and biomass encountered in this estuary may also be attributed to the fact that the different species are able to exploit of a number of different resources. The variation in stable isotope analysis of the different crab species throughout the estuary indicated that these crabs able to occupy the same habitat by feeding on a number of different resources and may preferentially select for a specific primary producer. A stable isotope of crabs in the salt marsh Swartkops estuary indicated that the dominant primary producer sustaining crab communities may even take place on a relatively smallscale. Sesarma catenata found at the inner marsh site recorded more depleted carbon signatures than those encountered in the other sites approximately 100 m away, and reflected signatures similar to the locally-encountered inner marsh plants. The relatively enriched nitrogen signatures of the anthropogenically-impacted Swartkops estuary is an indication of extensive inputs due to urbanization and industrialization, in contrast to the relatively pristine Mngazana estuary which exhibited low nitrogen signatures. Emphasis has been placed on the abiotic component of the exchange of nutrients and energy, although living organisms may also be transported, both actively and passively, between ecosystems. Little variation in either species composition or abundance was found between seasons for the larval distribution of brachyuran crabs on the east coast of South Africa. Due to the lack of published larval descriptions, larvae could not be identified to species level and it was therefore not possible to identify whether the larvae were hatched or spawned in an estuary or in a marine environment, or whether the larvae originated in the northern tropical regions. Frequent wind-reversals which are common in this region may retain larvae close inshore and supply the southern temperate locations with larvae from the northern locations. In conclusion, this study has shown that in highly productive systems with a number of potential primary producers, the crabs that inhabit the estuary show a marked diversity in resource utilization which could potentially allow a number of closely related species to occupy different trophic levels. This study also highlights the importance of locally produced sources in an estuary, which may occur on very small scales and this needs to be factored in with the design of any future stable isotope studies of this nature.

Here I provide the first report on Geukensia granosissima patterns of abundance along a tidal gradient within a mixed mangrove stand located in Tampa Bay, Florida, USA. Specifically, I examined 1) the relationship between G. granosissima size and density with mangrove root type (e.g. prop root, pneumatophore), and of density within the intertidal zones; and 2) the possible role of predation in shaping the lower zonation patterns displayed. Transect surveys located along the lower and upper population limit boundaries were conducted every two months over a ten-month period. Variables measured include size distribution, density of mussels, above ground mangrove prop and pneumatophore roots. To evaluate potential predator influence on mussel distribution, predator exclusion experiments were conducted in March and June 2016, using mock pneumatophore platforms at both high and low tidal elevations. Surveys indicated that over all dates mean mussel densities and percent cover were higher along the lower limit tidal elevation [mean (± SD) = 1280.3 ± 665.9 m-2 and 20.6 ± 3.78% respectively], versus that in the higher limit tidal elevation [102.4 ± 50.7 m-2 and 0.52 ± 0.17%]. Survivorship of mussels in the predator exclusion platforms placed at higher position within lower edge of the mussel tidal distribution was approximately 100% on both experimental dates. During March 2016, mussel survivorship was lower when predators had access to mussels with the greatest loss of mussels in the lower (26% survivorship) vs. higher (66.5%) tidal elevations after 48h. Similarly, when predators had access to mussels in June experiments, after just 24 h mussel loss was greater at lower (1% survivorship) vs. higher (80% survivorship) tidal elevations, possibly reflecting differences in predator densities, identities, and/or functional responses. Overall trends in the patterns of distribution of this population of G. granosissima suggest that the lower tidal boundary of the mussel is shaped by predation but that predation plays a lesser role in the high tidal areas.

This research looks at the change in ethical sensibilities towards a mangrove in a fishing colony in the periphery of Rio de Janeiro, Brazil, and at how they may have changed as the mangrove became a protected area and entered the environmental assemblage. Formerly called Z-1, this was the first of 800 cooperative fishing colonies founded along the Brazilian coast in 1920 as part of a government initiative. The study unveiled the following pattern around the mangrove: from being a source of livelihood and place for communal activities up until the 1970s, it became the locus of an environmental movement in the 80s and 90s after it was devastated by a big fire. The concrete outcome of the movement was the creation of the APARU, Area of Environmental Protection and Urban Regeneration, which meant that after more than seventy years under a system of tutelage by the Navy, the colony and the mangrove were subjected to an environmental form of governance administered by the City Council, and the mangrove went from being a taken-for-granted thing to an environmentally-oriented concept. It finally fell silent and isolated as it became increasingly polluted, even if ‘protected’ by a municipal decree. The main argument presented is that, as the mangrove passed from nature to environment, which implied a change in governance from the Navy to the Department of Environment, people found creative ways of holding on to its thingness, and to ethical values that at times conflict with the broader environmental assemblage. Those local ethics forge the links that sustain an ecological assemblage, and the ethics prescribed by the environmental governance currently in place can be undermined by more embedded values. That said, local knowledge and practices are environmentally informed, and different ways of being political emerge. This community was not only created literally on a mangrove, but it was also symbolically and politically reproduced through the mangrove, and even more so after it became a protected area. The dialectical outcomes of the relationships between human beings and the mangrove, and between human beings as they multiply, transform the landscape continuously, just as the mangrove in its perpetual unfolding impresses itself upon human matters and sustains the social ordering of things. As new elements are assembled around the mangrove, from discarded utensils to stories of environmental activism, the mangrove is enacted as heritage, as nature, as a biome, as culture, as pollution, as an institution, and as environment. This thesis hopes to contribute towards the broader body of literature on environmental anthropology, political ecology, and anthropology of moralities, by focusing on ‘human-disturbed environments’ (Tsing 2013) and bringing attention to the value of local perceptions in policy making.

Mangroves are intertidal ecosystems found along the tropical and subtropical coastlines.

Though globally recognised as ecosystems of ecological, biological and economical

remarkable importance, these ecotone formations are characterised by a continuously

increasing anthropization. However, very little studies have been focused on the impact of

various anthropogenic activities on the mangrove vegetation structure.

We have firstly (a) assessed the commercial and subsistence utilization of mangrove

wood products in the Littoral region (Cameroon estuary). Then, we have confronted the

subsistence usages of mangrove wood products in the Southern region (close to the mouth of

the Nyong River and Mpalla village (Kribi)) in comparison with the Littoral region. By doing,

we have compared the local residents‟ perceptions on environmental changes that occurred

within the two regional mangrove forests. Also, we have (c) studied the structural dynamic of

mangrove vegetation neighbouring the Douala city (Cameroon). Always in the vicinity of this

town, we have (d) reconstructed the original structure of largely disturbed mangrove forests.

Moreover, we have (e) map the mangrove structure in a non peri-urban setting located within

the Cameroon estuary. Here, we have finally (f) analysed the spatial distribution of a black

mangrove namely Avicennia germinans (L.) Stearn.

Our results underlined an excessive utilization of mangrove wood products in the

Cameroon estuary. We have showed that the frequency of mangrove harvesting was relatively

fewer in Kribi (Mpalla) and the mouth of the Nyong River. The local people inhabiting these

two localities perceived mangroves as less degraded areas. In contrast, those established

within the Cameroon estuary stated that mangroves were largely disturbed. When combining

the local people statements with our field observations, we recorded that it a complex mix of

causes (e.i. clear-felled corridors, agriculture, sand and gravel extraction, over-harvesting and

anarchic urbanization) that have led to the largely degradation (vegetation and sediment) of

the peri-urban mangroves in Cameroon. A diachronic analysis (1974, 2003, 2009) of their

coverage revealed that over the 35-year period, mangrove had decreases in cover of 53.16%

around Douala. We have also showed that in the peri-urban settings, wood harvesting was

commonly applied on the structurally more complex (highly dense stands neighbouring the

habitations) mangrove forests (Mboussa Essengue) and, in a lesser extent, on the structurally

more developed mangrove stands (fewer dense stands faraway from Douala). On the other

hand, the mapping analysis of the non peri-urban mangroves (distant from Douala) has

revealed that the structure of these intertidal forests was relatively less impacted. In the

Cameroon estuary, we also showed that A. germinans trees were randomly distributed on

almost one-half of the sampling plots and clumped at some scales on the remaining plots.

Accordingly, this species might play a significant role in the recovery process of artificial

gaps found in the non peri-urban areas.

The multi-disciplinary approach employed in this study has allowed a better

understanding of the direct and indirect impacts of anthropogenic activities on the mangrove

vegetation structure in Cameroon. These results constitute a fundamental data base quite

useful for the multi-temporal monitoring of these littoral ecosystems perpetually disturbed.

The application of similar approach in other mangroves facing high anthropogenic pressures

appears important.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Chilling events are infrequent but important disturbances in subtropical Florida. When temperatures drop to near freezing, significant mortality often accrues in mangrove forests. Chilling events play a role in maintaining structural diversity in mangrove forests, and in limiting mangrove poleward distribution. I examined the spatio-temporal distribution of chilling events in mangrove forests of southern Biscayne Bay by using Landsat TM5 images since 1989. Damage was usually confined to dwarf mangrove forest, especially when chilling temperatures were moderate and short in duration. However, damage from extended and severe freezes such as in January 2010 impacted larger trees as well. Recovery is gradual, often extending over multiple years, depending on disturbance severity. Plant communities respond to repeated chilling with increase in the dominance of black mangrove. In the absence of chilling events, patch level dynamics might lead to prevalence of a more homogenous tall red mangrove canopy in these wetlands. Such a trajectory may result with increasing temperatures expected under current global climate change scenarios

Os manguezais de Bertioga localizam-se próximos ao limite sul de distribuição dessa comunidade vegetal na costa brasileira e no hemisfério sul. Esses bosques são compostos por três espécies: Rhizophora mangle L., Avicennia schaueriana Stapf & Leechman e Laguncularia racemosa Gaertn f. e apresentam estrutura pouco desenvolvida. O manguezal do Rio Iriri possui um diâmetro médio de 8,48 cm, altura média de 6,55 m, densidade de 216 ind/0,1 ha e área basal de 1,29 m2m2/0,1 ha. Já no Rio ltapanhaú, .o diâmetro médio do bosque é de 10,41 em, com altura média de 6,83 m, densidade de 173 ind/0,1 ha e área basal de 1 ,69 m2/0,1 ha. Estimativas de biomassa nos dois locais de estudo resultaram em valores de 42,3 t/ha para o Rio iriri e 59,7 t/ha para o Rio Itapanhaú e a produção anual de madeira foi de 3,6 e 1,9 t/ha respectivamente. Esse baixo desenvolvimento estrutural é provavelmente devido às baixas temperaturas alcançadas no inverno e aos diversos estresses aos quais estão submetidos esses bosques em função das atividades humanas desenvolvidas na região. A produção de serapilheira desses bosques reflete seus baixos índices estruturais, embora trate-se de bosques de franja inundados duas vezes ao dia por marés de mais de 1 m de amplitude. A taxa média anual de produção de serapilheira foi de 5,6 t/ha no Rio lriri e 4,6 no Rio Itapanhaú. Padrões sazonais foram evidentes para os diversos componentes da serapilheira assim como uma sequência temporal das diversas fases fenológicas. As folhas apresentaram maior produção durante o verão. As flores mostraram picos no final dessa estação seguidas de picos de propágulos no outono. A queda de madeira apresentou maiores taxas principalmente nos meses de inverno. Os fatores que controlam essa sazonalidade estão provavelmente associados à temperatura e pluviosidade. Nesses manguezais a renovação desse material é alta, apresentando baixas quantidades de estoque de serapilheira no sedimento, cujos valores variam de 50 a 164 gPS/m2. Essa renovação se dá através da decomposição, que é bastante rápida, com taxas diárias médias de 0,006 para Rhizophora, 0,011 para Laguncularia e 0,015 para Avicennia. Além da diferença entre as espécies, foi observada uma diferença entre as estações e os sítios. As taxas do verão foram significativamente mais altas que as do inverno. Além disso, o Rio Iriri apresentou taxas médias mais elevadas que o Itapanhaú. Embora o processo de decomposição seja intenso nesses manguezais pela existência de condições favoróveis, a maior parte da renovação se dá através da exportação da serapilheira pelo movimento das marés. A partir da elaboração de um modelo ecológico da dinâmica da serapilheira incluindo sua produção, estoque e decomposição, foi possível estimar essa exportação cujos valores estão em torno de 0,7 gPS/m2 por dia com uma exportação acumulada anual de cerca de 2,5 tPS/ha, o que significa que estes manguezais exportam aproximadamente 50 por cento da serapilhelra que produzem. Essa dinâmica da serapilheira influencia também a ciclagem de nutrientes nesse ecossistema. Para compensar a exportação de materiais esses manguezais apresentam retranslocação de nutrientes como o nitrogênio e o fósforo, mecanismo no qual esses elementos são reabsorvidos da folha antes de sua queda. A imobilização, outro mecanismo para conservar nutrientes durante a decomposição, não foi significativa nesse estudo, ocorrendo apenas com nitrogênio em folhas de Laguncularia. Apesar da retranslocação registrada nesses bosques, tanto para o nitrogênio quanto para o fósforo, esses manguezais não se mostraram eficientes no uso de nutrientes, provavelmente, porque estes estejam disponíveis no sedimento em quantidades adequadas. A variação anual da concentração de nutrientes nas folhas da serapilheira mostrou um padrão sazonal com maiores valores no inverno e menores no verão. Já as folhas verdes não apresentam essa sazonalidade tão nítida:o que ocorre, portanto, é uma maior retranslocação durante a época de maior produção de folhas, mantendo os teores desses nutrientes na copa.
The mangroves in Bertioga estuary are mixed forests composed by three species: Rhizophora mangle L., Avicennia schaueriana Stapf & Leechman and Laguncularia racemosa. Gaertn f. Both study sites are frequently flooded by tide waters and can be classified as fringe forests, according to the physiographic types. The Rio Iriri site had a DBH of 8,48 cm, and a mean height of 6,55 m, density in this site was 216 trees/0,1 ha and the basal area was 1,29 m2/0,1 ha. In Rio Itapanhaú, mean DBh was 10,41 cm, with mean height of 6,83 m, density of 173 trees/0,1 ha and basal area of 1,69 m2/0,1 ha. Based on the structural parameters it is possible to see that DBH and tree height of these forests are equivalent to other fringe sites, but density and basal area are much lower. The DBH increment was similar to measurements presented in other studies. However wood production was much lower, because of low density. Biomass estimate of each site forest were: for rio Iriri the biomass was 42.3 t .ha-1 while in rio Itapanhaú it was 59.7 t. ha-1. Mean annual littertall rates were 5.6 t.ha-1 .yr -1 in Rio Iriri and 4.6 t.ha-l.yr-1 in Rio Itapanhaú. However, these forests are fringe mangroves which normally have higher production rates. In this study litter fall production was seasonal with a trend of alternate peaks for the various components which appears to be a sequence within the year. Leaf fall is higher in the summer which is the rainy season (from November through February) followed by the miscellaneous peak in the autumn (from March through May) while the period of higher wood production is from June to October. This pattern suggests a coordination among phenological phases. The factors controlling those variations are still not clearly established. Environmental conditions related to rainfall and temperature are the most probable responsibles for this influence. The decomposition potential of the mangrove sites in Bertioga region (23º51\'5) was high and this might be due to high temperature associated to high rainfall and frequent flooding that create good conditions (hot and humid environment) to accelerate the organic matter degradation. Species showed different decomposition rates. The highest value of k were observed for A. schauerianna (0.015 d-1) followed by L. racemosa (0.011 d-1 ). The lowest value of k occurred in R. mangle (0.006 d-1 ). Brazilian studies of litter decomposition with the same species showed the same gradient of species specific rates. Those differences can be explained by differences in the resource quality. Chemical composition of leaf material is very important in determining its decomposition rate. There was also a significant difference in decomposition rates among species and between sites and seasons. Iriri had higher decomposition rates than Itapanhaú. Summer season had higher decay rates than winter. The processes of decomposition are regulated by the combined effects of the resource quality and the physico-chemical environment on the community of decomposer organisms. According to these main controlling factors, differences observed among species should be attributed to differences in substrate quality, while differences among sites or seasons would be related to different environmental conditions. Seasons differences would be more related to climate features while site differences in this study would be more determined by edaphic features. Although there was an increase in nutrient percentage during decomposition, there was not an increase in their absolute concentration or net accumulation. In Bertioga mangrove forests immobilization was low or absent perhaps because the studied sites are fertiles. In addition, it is only observed in Laguncularia leaves because it is the species with lowest nitrogen concentration what would be a limiting factor. The high content of nitrogen in Rhizophora leaves could be the reason why this nutrient had no net immobilization in this study. Apparently, the absence of phosphorus immobilization could be its availability in both ways, plant tissue and sediment. Mean values of litter standing stock ranged from 50 to 164 g.m-2 throughout the year which are low values, but considering that both are fringe sites it would be expected. Seasonal patterns of litter standing crop can be related to seasonal patterns of litter production, decomposition or hydrological variations. Since in Bertioga decomposition plays a small role because most of litter is removed and hydrology does not show a marked seasonal pattern, litter export and stock reflect the seasonality of litter production and may be a little modified by variations in tidal height. This is not valid for wood component that showed a different behaviour because it is not very influenced by export. Litter turnover rates of this study ( 5.1 and 4.7 yr-1) are higher than other values found in other mangrove forests. The values obtained for leaf fall (14.92 to 24.22 yr-1) in this study are very high even for fringe forest. Analysis of turnover rate for each month indicates that these rates vary throughout the year. especially for leaf fall. The period of higher turnover rates seems to be related to higher litterfall rates, but it may be also an interaction with the variation of tidal amplitude and decomposition. It is possible to see that there is a coincidence of the months of higher turnover rates with the months of higher tidal amplitude. Since measurement of litter export is very difficult because water movements are very complex in a mangrove site and due to the importance of litter dynamics to the tunction of a mangrove ecosystem. the development of a litter dynamics model was useful to understand those processes and organic matter fluxes and to the estimate of export rates. The litter model includes littertall as the input of organic matter, litter standing crop as the storage of organic matter and decomposition and export as outputs of organic matter from the system. Based on these figures it is possible to roughly estimate an annual export of 2,5 t.ha.yr -1. The conclusion is that in these mangrove forests at least 50 per cent of its production is exported by tides. Nutrient content in canopy of mangroves in Bertioga is high and although retranslocation takes place, nutrient concentrations in litterfall are still high. C:N of leaf litter in these forests are low and decomposition should not be nutrient limited. Then litter decay occurs fast with low or none immobilization. These are characteristics of sites with high availability of nutrients. In these forests, although nutrient use efficiency is not very high, nutrient recycling is occurring via retranslocation and not via immobilization during decomposition probably because they are fringe forests. The high retranslocation rates could be a mechanism to prevent loss of nutrients by export. Another important characteristic of these mangroves was the seasonal pattern of nutrient cycling. Nutrient content of leaf fall varies throughout the year with high concentration during winter. Retranslocation also showed a seasonal pattern with higher rates in the summer, resulting in lower nutrient levels in leaf litter and the consequence is a higher nutrient use efficiency in this period of leaf production.

Mangroves and saltmarshes are ecologically important coastal ecosystems; unfortunately, these low-lying coastal ecosystems are vulnerable to global climate change. As sea-levels rise, mangroves are expected to shift their distribution landward towards higher elevation sites that are occupied by other plants, including saltmarsh taxa. Therefore, mangrove recruits at the leading edge of expansion may interact with diverse assemblages of saltmarsh plants, and these interactions could influence the success of mangrove encroachment into higher tidal-elevation areas. The purpose of the research presented here was to investigate empirically the ecological interactions that may influence the recruitment of the black mangrove, Avicennia germinans, into saltmarsh habitats. Saltmarsh plants frequently occurred at the landward boundary of mangrove forests at two sites selected for field studies along the west coast of Florida: Cannon Island and Upper Tampa Bay Park. On Cannon Island, two different field tests investigated mangrove propagule entrapment and dispersal within saltmarsh vegetation. In the first experiment, the entrapment of mangrove propagules within saltmarsh plants, exhibiting different growth forms, was examined during seasonal high tide events. Natural polyculture plots retained a mean (±;SE) 59.3% (±;11.0) of emplaced propagules. Monocultures varied in their propagule retention capacities with plots of S. virginicus retaining on average 65.7% (±;11.5) of transplanted propagules compared to 7.2% (±;1.8) by B. maritima and 5.0% (±;1.9) by S. portulacastrum. Monocultures of the salt marsh grass, Sporobolus virginicus, and natural saltmarsh polycultures containing S. virginicus retained significantly more propagules than either of two succulent plants (i.e., Batis maritima and Sesuvium portulacastrum). Using digital images, saltmarsh plant structure was quantified; the number of entrapped mangrove propagules displayed a significant and positive correlation (r2 = 0.6253, p = 0.00001) with the amount of structure provided by saltmarsh plants. Therefore, the first field study identified structural and functional differences between saltmarsh plants. A second field study employed marked propagules in order to further examine the dispersal patterns of propagules at saltmarsh boundaries comprised of plants with different growth forms (i.e., grass vs. succulent) during seasonal high tides. Saltmarsh plant boundaries erected by taxa with distinct growth forms differentially influenced the proportion of propagules that dispersed seaward and the distance propagules moved seaward. In fact, nearly twice as many propagules dispersed seaward at boundaries erected by succulent plants compared to boundaries composed of grass. The results of this field study support my previous findings that propagule dispersal is comparatively lower in saltmarsh grass than in succulent saltmarsh plants. The findings from these two field studies suggest that the permeability of boundaries formed by saltmarsh plants may modulate landward dispersal of A. germinans propagules. The final field study was conducted at Upper Tampa Bay Park, where a second species of saltmarsh grass, Monanthochloe littoralis, co-occurred with the grass, S. virginicus, and succulent saltmarsh plants to form a mosaic landscape of saltmarsh plant patches. Patches were weeded to create 3 saltmarsh treatments: 1) M. littoralis monoculture; 2) S. virginicus monoculture; and 3) polycultures containing both grasses and at least one other saltmarsh taxa. Propagules of A. germinans were emplaced into saltmarsh patches and followed for 11 weeks. On the last sampling date, the greatest number of A. germinans (n = 51) had successfully established as seedlings within the M. littoralis monoculture plots. In contrast, only 20 (22% of the propagules initially emplaced) A. germinans seedlings established in S. virginicus monoculture plots. These findings suggest that among grass taxa, species identity influences mangrove establishment success, which builds upon our previous findings that demonstrated that saltmarsh growth form (i.e., grass vs. succulent) influenced mangrove propagule dispersal. Combined the findings from these field studies indicate that interactions among the early life history stages of black mangroves and neighboring plants influence mangrove recruitment. Specifically, these field studies provide empirical evidence that the species composition of saltmarsh plants influences mangrove propagule dispersal and seedling establishment. The work presented here has implications for understanding the suite of ecological interactions that may influence mangrove encroachment into saltmarsh habitats at higher tidal elevations as sea-levels rise.

Gastropods are one of the most diverse species groups in mangrove habitats, however, many of their specific roles in relation to ecological patterns and processes are currently largely unknown. The overall aim of this research project was to provide basic ecological information for key gastropod species from subtropical mangroves within a protected area. South African mangroves cover relatively small areas and are restricted to estuaries, these habitats therefore present unique opportunities and challenges to the species that occur in them. Three gastropod species, Terebralia palustris, Cerithidea decollata, and Melanoides tuberculata, all occur at their natural southernmost range limit within South Africa and were selected based on their prominence and occurrence in mangrove habitats of the iSimangaliso Wetland Park, a UNESCO World Heritage Site. Trophic linkages and resource partitioning, resource utilization rates, and ecological resilience were investigated respectively using: 1) a stable isotope (δ15N and δ13C) approach; 2) an experimental approach to quantify feeding dynamics (ingestion rate, consumption/digestion efficiency and grazing impact); and 3) a mixed-effects modelling approach to relate population responses to environmental variables. The diet of T. palustris was seasonally variable and a number of sources were incorporated by different sized snails, but their grazing impact on microphytobenthos was not significant. The results also indicated an ontogenetic shift in the dietary niche for T. palustris through robust partitioning of resources between different size classes. The diets of C. decollata and M. tuberculata were dominated by different primary resources as a function of where they occurred in the mangroves. Melanoides tuberculata consumed a wide variety of primary resources, a typical trait of an opportunistic generalist species. The ingestion rate of M. tuberculata was not dependent on the availability of microphytobenthos, and was highest when conditions were oligotrophic. The resilience of C. decollata was related to the tree-climbing behaviour of this species and its occurrence was best explained by sediment conductivity. These responses were considered in conjunction to what has previously been reported on the resilience of the mangrove trees. The results of this research project have provided new basic ecological information for all three gastropod species in this data-deficient subtropical region. This information can potentially be used in comparative studies for these species in other regions or in broader scale ecological studies. Terebralia palustris has recently experienced a range contraction along the South African coastline. This research project has shown that the diet of this species is highly variable and that food limitation and competition for resources should be considered as potential drivers of the local decline. Cerithidea decollata has in contrast expanded its distributional range in this region. This research project has shown that this species has a generalist diet and exhibits traits in relation to tolerance that are expected to have facilitated its expansion into temperate saltmarsh habitats that occur in dynamic estuaries. Melanoides tuberculata is a globally invasive species, and as South African populations are within its native range, ecological information from this region is valuable as it can be used to investigate the potential ecological effects following introduction into new habitats beyond the native range. Biological drivers have a significant impact on mangrove ecosystem functioning, particularly in relation to recycling and the retention of organic carbon generated through primary productivity. Understanding the ecological linkages that maintain ecological functioning and stability is therefore an important step towards conserving and sustainably managing threatened ecosystems such as mangrove forests.

Mangrove stands are uncommon within semi-arid climates and rare within inland systems. It is uncertain whether the same environmental variables influence mangroves growing in a semi-arid climate as the trees growing in tropical and sub-tropical areas. Field studies conducted on the ecophysiological responses of the mangrove species Avicennia marina are few; however hydrological regimes are considered the key factor influencing mangrove stand zonation, structure and individual tree growth. The Gascoyne region of Western Australia provides a unique opportunity to investigate whether mangroves growing within an inland semi-arid environment display similar growth patterns and ecophysiological responses to their coastal counterparts. This study investigates the distribution, structure and condition of the mangrove A. marina growing at Lake MacLeod and coastal and riverine stands near Carnarvon, Western Australia. Hydrological categories based on freshwater inputs, tidal influences, distance from permanent water sources and sediment elevations were used to investigate the environmental conditions present within specific hydrological regimes. Mangrove tree responses to environmental conditions were evaluated by assessing above-ground biomass, shoot production, water-use efficiency, photosynthesis, specific leaf area, weight and total chloride content. The overarching objective was to determine the environmental factors influencing the presence, morphology and physiological state of A. marina growing at inland, coastal and riverine sites in a semi-arid climate. Soil moisture content, organic matter content, average and seasonal range in sediment EC, and distance from the permanent water sources were found to influence vegetation characteristics at Lake MacLeod. Soil moisture content was highest close to permanent ponds and at lower sediment elevations. Sediment salinity was highest close to pond edges, although the majority of the lake bed is hypersaline due to high evapoconcentration. The environmental gradients are complex at Lake MacLeod as a result of the unique hydrological regime. Seawater supply to permanent ponds is constant via an underground karst system which enters the lake through vents and seepages present along the western edge of the lake bed. It is evident that the constant supply of marine water is the key environmental factor supporting mangrove presence and structure. Average mangrove tree height, basal area, density and canopy cover are greatest near the permanent ponds. Mangrove density and height was also high, though patchy away from the ponds where saline seepages occurred. A high density of stunted mangroves was found on lake shorelines receiving periodic saline flooding via wind surges. Samphire cover was also greatest close to the permanent ponds, demonstrating that both mangrove and Samphire presence and importance is influenced by consistency of water availability. Sediment conditions were significantly different between inland and coastal sites, with sediment salinity and moisture content higher at Lake MacLeod. The ecophysiological responses displayed by A. marina in different categories of hydrological regimes revealed that consistency of water supply, irrespective of salinity, is an important driver of long and short-term productivity, water-use efficiency, leaf size and weight, and tree height. In general, short and long-term production was inversely proportional to distance from permanent water sources, although it was highly variable due to seepages away from the permanent ponds. Mangrove trees growing at the landward edge of coastal sites were the most water-use efficient (~ -28 δ¹³C), relative to the inland Lake MacLeod trees (~ - 26 δ¹³C), and was directly linked to water supply not quality. Photosystem health in trees growing at both the riverine stands (yield 0.66 ± 0.01) and inland stands found at greater distances from ponds (yield 0.065 ± 0.02), were significantly lower than all other trees in this study. Relative maximum electron transfer rate was also significantly lower at these sites, suggesting that the riverine trees were affected by other stresses such as herbicides. Mangrove trees near permanent water sources, or that received tidal flushing, displayed larger leaves and lower specific leaf weight, indicating that A. marina has the ability to not only tolerate hypersaline conditions but also acclimate to harsh and variable conditions via changes to ecophysiological responses and morphology. This research has developed a better understanding of how A. marina persists at Lake MacLeod and whether these trees are under greater stress as opposed to the mangroves growing at coastal stands. Sediment conditions between coastal and inland sites were significantly different, but it was distance from permanent water sources that influenced mangrove stand features. Therefore, the key environmental variable influencing distribution, structure and ecophysiological state of A. marina growing in a semi-arid climate is predominantly water availability.

I carried out an observational study of historic high resolution aerial imagery spanning six decades (1950-2014) to identify recent and historic spatial extent of mangrove forests, within the municipal boundaries of the City of Tampa, Florida USA. My objectives were to map mangrove distribution and spatial extent and any change or patterns of change discernable. I observed variable patterns of change and rates of expansion varied between sites spatially as well as within sites between time intervals. I found notable changes in mangrove extent in the Tampa from historic and modern aerial imagery for the ~64-year period between 1950 and 2014. There were significant losses in areal extent between 1950 and 1973, much of which could be directly attributed to anthropogenic modification of the Tampa coastal landscape. All the regions observed had recovered or surpassed their original extent by the end of the period reviewed (1950-2014). It appears much of the recovery observed is a result of recolonization of created or modified shorelines. Results of these observations may contribute to the body of information used to inform conservation and management objectives in the City of Tampa and Tampa Bay.

La situation des mangroves dans le monde reste préoccupante malgré la prise de conscience de leur rôle dans le maintien de la biodiversité côtière. Les pratiques non durables de l’aquaculture extensive sont toujours majoritairement mises en cause. Le besoin d’une meilleure gestion côtière se fait sentir depuis une vingtaine d’années. Il faut reconnaitre que les avancées restent insuffisantes, particulièrement en Indonésie. Ce travail de thèse a été réalisé dans le cadre du projet INDESO. Ses objectifs étaient de décrire les changements dans les mangroves en termes de superficie, de structuration ou de composition spécifique afin d’étudier, à fine échelle spatiale, la diversité des peuplements de palétuviers, leur capacité de régénération et les tendances d’évolution de l’écosystème. Pour cela, j’ai utilisé 28 images satellitaires de télédétection optique à très haute résolution spatiale (THRS) acquises dans la période de 2001 à 2015 sur deux sites d’étude, Bali, Indonésie. J’ai participé aux inventaires forestiers et à l’identification des espèces de palétuviers du stade plantule au stade adulte. J’ai procédé par analyse visuelle des images pour différencier les plantations de palétuviers des forêts naturelles. J’ai examiné les différences entre les signatures spectrales des différentes formations de palétuviers en fonction des configurations angulaires. J’ai réalisé sur chaque image une classification supervisée qui m’a permis de comptabiliser avec une précision de quelques mètres carrés la superficie occupée par les mangroves et d’évaluer la robustesse d’une cartographie à fine échelle de zonations de mangroves.Les résultats obtenus sur l’estuaire du Perancak dégradé par l’aquaculture montrent que la surface de mangrove augmente après 2001 mais que les pratiques de plantations dans cette région n’ont rien à voir avec la réhabilitation de mangroves. Des différences majeures entre plantations et forêts naturelles existent. Ces plantations sont des cultures à très forte densité de Rhizophora, alors que les faciès naturels sont dominés par Avicennia et Sonneratia. Nos résultats montrent que la capacité de régénération dans ces plantations reste très inférieure à celle observée dans les forêts naturelles et que, si régénération il y a, c’est avec des plantules des espèces natives. A partir de l’analyse des imges, nous avons identifié les 136 bassins qui ont fait l’objet de plantations et donné l’année du semis. Le suivi de l’évolution du nombre de pixels classés ‘mangrove’ à l’intérieur de chaque bassin planté montre une grande variabilité des taux d’expansion sur 14 ans, ceci suggérant des conditions environnementales spécifiques à chaque bassin et donc l’inconséquence des pratiques généralisées de plantations à Rhizophora. Enfin, les capacités de colonisation des espèces natives y compris à l’intérieur de certains bassins semblent avérées dans cet estuaire pourtant très fragmenté. Les résultats obtenus sur les mangroves protégées de la région de Nusa Lembongan montrent le potentiel des images multi-spectrales satellitaires THRS pour cartographier différentes zonations de mangroves. Ce potentiel de discrimination est observé assez stable au cours du temps entre 4 espèces. Toutefois, des configurations angulaires avec un soleil de face ou un angle de visée proche de la verticale pourraient générer de la confusion notamment sur les peuplements à canopée ouverte. Nous avons obtenu probablement les premières cartes de mangrove de Nusa Lembongan qui montrent la complexité des zonations forestières et soutiennent l’enjeu de leur protection.L’ensemble de mon travail plaide pour une meilleure interprétation physique de la variabilité des signatures spectrales et texturales de mangrove. Il fournit des recommandations comme la nécessité d’un moratoire sur les monocultures à Rhizophora et des méthodes simples, embryons de futurs observatoires locaux pour l’évaluation et le suivi des plans de gestion côtière mis en place
The situation of world’s mangroves remains a matter of concern, despite the public awareness about their role in the sustainability of coastal biodiversity. Extensive and intensive aquaculture practies are mainly called into question. The need for a better integrated coastal zone management arises since a couple of decades. It must be recognized that progress is insufficient especially in Indonesia.The present PhD work has been carried out in the frame of the INDESO project. The objective was to describe mangrove changes in terms of area expansion, forest structure and species composition before studying, at fine scales, the diversity of mangrove stands, their regeneration capacity and the evolution trends of the whole ecosystem in a given region.In order to achieve this aim, i used 28 very high spatial resolution (VHSR) optical satellite images aquired between 2001 and 2015. I also participated in forest inventories and species identification from the seedling to the adult stages. I visually analysed the set of images for allowing the discrimination of planted mangroves from natural ones. I examined the influence of acquisition geometry parameters on the variability of mangrove spectral signatures. Thanks to supervised maximum likelihood classifications, I succeeded in evaluating the expansion area of mangrove with an accurracy of few square meters and I proceeded in assessing the robustness of fine scale mapping of mangrove zonations.Results obtained in the analysis of the Perancak estuary highlighted that mangrove area is expanding since 2001. The plantation practices were however presented as disrespectful of any sustainable management plan. Indeed, our simple field data indicated strong differences between mangrove plantations and natural forests. Plantations were shown to be cultures of only Rhizophora species with high planting density whereas natural forest stands are composed of Sonneratia and Avicennia mangrove trees. In addition, we highlighted that the regeneration capacity in planted areas remains very lower than the ones clearly observed in natural areas. Moreover, the only regenetive process in plantations seems to be with native species and not with the planted ones. From the analysis of the VHSR images, we identified aquaculture ponds that were planted and their planting year. Consequently, we suceeded in monitoring the mangrove expansion inside every planted pond. Important variability of expansion rate was pointed out, this suggesting contrasting environments in each pond and the inadequacy of cultures of Rhizophora everywhere. The observation of natural colonization in many areas of the estuary, pond floors included, was an interesting point to mention.Besides, results obtained in the study of the protected mangrove region of Nusa Lembongan assessed the potential of multispectral VHSR satellite images for mapping mangrove zonations. Four mangrove zonations mainly dominated by different species exhibit signatures that can be differentiated over years. Different image acquisition parameters may, however, generate confusion in classification. This is particularyly true when forest stands with open canopies are observed with sun frontward or with a near vertical viewing angle because of sun light interaction with the clear waters. We probably obtained the first detailed maps of mangrove zonations in the region. They showed a complex spatial organization of mangrove zonations.The whole of my work advocated for further remote sensing works aiming at the physical interpretation of spectral and textural signatures of mangroves. It provided recommendations such as a moratorium onf Rhizophora plantation and simple methods that will be, we hope, starting points for closing the knowledge gap that hampers monitoring of future coastal zone management plans

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This work was carried out from August 2007 to July 2011, in Itabora?, RJ, Brazil, and aimed to identify the Calliphoridae species exist in a mangrove swamp, verifying which are the predominant species, highlighting the proportions of males and females, and also analyzing the influence of abiotic factors such as temperature, humidity and moon phases, and also providing an analysis of the abundance, richness, diversity and similarity between the periods of sampling, ecological relationships between species of the same family and the ecological relationship between Calliphoridae and Phoridae parasitoids in Guapi-Mirim Environmental Protection Area, (Guapi-Mirim EPA) in the same city. Semiweekly collections were carried out over 48 months (96 collections). The traps were suspended at a height of 1.20 m above the ground for a period of 48 hours for each collection. To trap and collect the flies, four plastic traps (35 cm x 15 cm) were placed 100m apart each other in the studied area. The bait used was based on fish (sardine) in decomposition. The insects caught were killed by asphyxiation with 70% ethanol inside the trap. After asphyxiation all specimens were put into plastic pots containing 70% ethanol. The specimens were taken to the Laborat?rio de Transmissores de Leishmanioses (Setor de Entomologia M?dica e Forense) - IOC/FIOCRUZ, RJ, where they were separated by the collection day, counted and then identified using a stereoscopic microscope and the dichotomous keys for families and species. The abundance of Calliphoridae flies was statistically analyzed using the Statistica 7.1 program (StatSoft 2005) for the non-parametric test Kruskal-Wallis one way ANOVA (p< 0.05). Also the Kendall Tau Correlation test, Mann-Whitney (significance of 95%; p<0.05) and chi-square test (?2) were used to analyze. The Shannon-Wiener diversity index, Bray-Curtis similarity and Euclidean Distance were used. A total of 4,531flies were collected. These flies belonged to ten (10) species of the Calliphoridae family: Chrysomya megacephala (Fabricius, 1794) (86.40%), Chrysomya albiceps (Wiedemann,1819) (5.72%), Cochliomyia macellaria (Fabricius, 1775) (4.94%), Chrysomya putoria (Wiedemann, 1818) (2.10%), Lucilia eximia (Wiedemann, 1819) (0.30%), Cochliomyia hominivorax (Cocquerel, 1858) (0.22%), Chloroprocta idioidea (Robineau-Desvoidy, 1930) (0.20%), Hemilucilia segmentaria (Fabricius, 1805) (0.04%), Hemilucilia semidiaphana (Rondani, 1850) (0.04%), Lucilia cuprina (Wiedemann,1830) (0.04%). The species C. megacephala was the one that presented the greatest abundance. Spring was the preferred season for all species; temperatures between 30.5 and 32.40C and relative humidity between 56.8 and 61.7% were considered those where there was a frenzy of oviposition; the full and new moons were the phases during which there was a higher occurrence of flies; Megaselia scalaris occurred more frequently in the most abundant Calliphoridae species in the same season of the year thus allowing greater dispersion of eggs; Calliphoridae species had a higher rate survival with increased food resources resulting from the polluting activity
Este trabalho foi realizado entre agosto de 2007 e julho de 2011, no Munic?pio de Itabora?, RJ, Brasil, e teve como objetivo identificar as esp?cies de Calliphoridae existentes em uma ?rea de mangue, quantificar as predominantes, destacando as propor??es de machos e f?meas, e tamb?m analisar a influ?ncia de fatores abi?ticos, tais como temperatura, umidade do ar e fases lunares; e ainda relacionar a abund?ncia, a riqueza, a diversidade e a similaridade entre os per?odos de coletas, rela??es ecol?gicas entre as esp?cies da entomofauna da mesma fam?lia e a rela??o ecol?gica entre Calliphoridae e Phoridae parasit?ides dentro da ?rea de Prote??o Ambiental de Guapi-Mirim (APA de Guapi-Mirim), em Itabora?. Durante 48 meses, foram realizadas 96 coletas, uma a cada 15 dias. Em todas as capturas, foram utilizadas armadilhas confeccionadas em recipiente pl?stico com 35 cm de altura e 15 cm de di?metro. Cada uma das quatro armadilhas foi suspensa a uma altura de 1,20 m do solo contendo 100g de isca de peixe (sardinha) em decomposi??o por um per?odo de 48 horas. Ap?s cada captura, todos os esp?cimes foram mortos no interior das armadilhas por asfixia utilizando etanol 70%. Em seguida todos os indiv?duos foram acondicionados em potes pl?sticos, contendo etanol a 70% e encaminhados ao Laborat?rio de Transmissores de Leishmanioses (Setor de Entomologia M?dica e Forense), IOC-FIOCRUZ, RJ, em seguida todos os esp?cimes foram separados por dia de coleta, identificadas e quantificadas. Para tal procedimento utilizou-se um microsc?pio estereosc?pico e chaves dicot?micas para a identifica??o da fam?lia e das esp?cies. As an?lises estat?sticas foram feitas utilizando o programa estat?stico Statistica 7.1 (STATSOFT, 2005), atrav?s do teste de Kruskal- Wallis one way ANOVA, teste de qui- quadrado (?2), Mann-Whitney e correla??o de Kendall Tau (p<0,05). Foram utilizados os ?ndices de diversidade de Shannon-Wiener e similaridade de Bray-Curtis, assim como a Dist?ncia Euclidiana. Foram capturadas 4531 moscas pertencentes a dez (10) esp?cies da fam?lia Calliphoridae: Chrysomya megacephala (Fabricius, 1794) (86,40%), Chrysomya albiceps (Wiedemann,1819) (5,72%), Cochliomyia macellaria (Fabricius, 1775) (4,94%), Chrysomya putoria (Wiedemann, 1818) (2,10%), Lucilia eximia (Wiedemann, 1819) (0,30%), Cochliomyia hominivorax (Cocquerel, 1858) (0,22%), Chloroprocta idioidea (Robineau-Desvoidy, 1930) (0,20%), Hemilucilia segmentaria (Fabricius, 1805) (0,04%), Hemilucilia semidiaphana (Rondani, 1850) (0,04%), Lucilia cuprina (Wiedemann,1830) (0,04%). A esp?cie C. megacephala foi aquela que apresentou a maior abund?ncia, a primavera foi a esta??o do ano em que todas as esp?cies mostraram maior prefer?ncia; as temperaturas compreendidas entre 30,5 e 32,40C e a umidade relativa do ar entre 56,8 e 61,7% foram consideradas aquelas onde houve frenesi de oviposi??o; nas luas cheias e novas houve maior ocorr?ncia de moscas capturadas; Megaselia scalaris se utilizou de esp?cies abundantes nas mesmas esta??es do anos em que ela ocorreu com maior frequ?ncia, possibilitando assim maior dispers?o de ovos; a maior disponibilidade de recursos alimentares resultantes da atividade poluidora tempor?ria ofereceram uma melhor condi??o de sobreviv?ncia para as esp?cies os Calliphoridae.

Os manguezais tropicais são considerados um dos ecossistemas mais produtivos do mundo, sendo caracterizados pela alta taxa de ciclagem de matéria orgânica e nutrientes que ocorre entre os oceanos e os ambientes terrestres. Embora os manguezais sejam considerados áreas de proteção ambiental, a destruição desses ambientes é progressiva, devido a atividades industriais e portuárias nos estuários. Nos manguezais, a ciclagem de nutrientes está diretamente relacionada às atividades e a diversidade das comunidades microbianas presentes no solo. Este trabalho está inserido em um projeto mais amplo dentro do programa BIOTA/FAPESP, no que tange aos estudos da biodiversidade no Estado de São Paulo e utilização dessa biodiversidade de modo sustentável. O objetivo deste trabalho foi avaliar as estruturas e diversidade das comunidades de Bacteria, Archaea e Fungi presentes no solo de manguezal preservado da Ilha do Cardoso-SP. As amostras foram analisadas pelas técnicas de T-RFLP, ARISA, clonagem e seqüenciamento a fim de obter uma caracterização das estruturas das comunidades microbianas de uma área de manguezal preservado em comparação com os ambientes adjacentes de restinga e floresta e também a um manguezal antropizado. Os resultados permitiram concluir que o manguezal possui características exclusivas, com a presença de organismos distintos, revelando um possível potencial biotecnológico a ser explorado. Adicionalmente, os dados revelaram que a ação antrópica afetou as estruturas dessas comunidades de modo a ser notada uma sensível diminuição de diversidade no manguezal antropizado, evidenciando, dessa maneira, a importância da preservação desse ecossistema
The tropical mangroves are considered one of the most productive ecosystems of the world, being characterized by the high tax of organic matter and recycling of nutrients, that happens between the oceans and the terrestrial habitats. Although the mangroves are considered areas of environmental protection, the destruction of those ecosystems is progressive, due to industrial and port activities in the estuaries. In mangroves, the recycling of nutrients is directly related to the activities and to the diversity of microbial communities present in the soil. This work is part of a wider project inside of the program BIOTA/FAPESP, with respect to the studies of the biodiversity in the State of São Paulo and use of that biodiversity in a maintainable way. The objective of this work was to evaluate the structures and diversity of communities of Bacteria, Archaea and Fungi present in the soil of preserved mangrove of Ilha do Cardoso-SP. The samples were analyzed by T-RFLP and ARISA techniques, cloning and sequencing in order to obtain a characterization of the microbial communities structure of preserved mangrove area in comparison with the adjacent environments of restinga (tropical moist forest) and forest and also to a degraded mangrove. The results allowed concluding that the mangroves present exclusive characteristics, with the presence of distinct organisms, revealing a possible biotechnological potential to be explored. Additionally, the data revealed that the human action affected the structures of those communities in a way to be noticed a sensitive diversity decrease in the degraded mangrove, evidencing, this way, the importance of the ecosystem preservation

This study was conducted to determine the role of flower-visiting bats as pollinators at the mangrove areas of Peninsular Malaysia. The mangrove trees of the genus Sonneratia, even though reported mainly pollinated by bats, are lacking in research regarding their pollination ecology. Therefore, the effectiveness of bats as pollinators was studied from the pollen loads on their bodies, as well as from pollen grains deposited on the stigmata during their visits to the Sonneratia flowers (Sonneratia 'caseoiaris, S. alba and S. ovata). Observations of other nocturnal visitors of the flowers were conducted to further assess the relative importance of bats as pollinators. The flowering biology of the three Sonneratia species was also examined to infer the breeding system and reproductive synchrony of the trees and their pollinators. Bats were the effective pollinators of S. caseolaris and S. alba trees, depositing sufficient pollen grains on the stigmata for pollination. The flowering biology of these two Sonneratia species (flower morphometrics, nectar secretion rate, nectar sugar concentration and anthesis phase) also suggests that these species uses bats as their principal pollinators. Even though the morphology of the S. alba flowers and visitor observations indicated pollination by moths such as sphingids, bats nonetheless were responsible for depositing most of the pollen loads on the stigmata of the flowers. Examinations of reproductive parts (pollen and ovules) indicated that the three species show obligate autogamy. Exclusion experiments on S. caseolaris however showed reduced pollination success when bats were deterred from visiting the flowers, further confirming the importance of bats as Sonneratia pollinating agents as compared to other visitors.

ABSTRACT Classifying and Mapping Diversity in a Species-Poor System: the mangrove meta-community of Laguna Chacahua National Park, Oaxaca, Mexico by Elizabeth Kay Weisgerber Both field transects and imagery grid plots were analyzed with the goal of creating a community classification map for the mangrove forest of Parque Nacional Lagunas de Chacahua. In total, data was collected in 49 sites throughout the park, recording measures such as DBH, basal area, estimated dominance, frequency, cover and relative dominance. Field locations were marked and georeferenced with a GPS and grid plots overlaid on satellite imagery of the park were generated via a random number table. Species' attributes delineating the identifiable features for each dominant species within Chacahua were noted and used to recognize patterns in species assemblages. Fourteen distinct ‘sub-communities’ within the mangrove meta-community were recognized using this data and verified with 165 field photos. Relative dominance values were compared between field and grid data. These data revealed a similar pattern with Rhizophora mangle being most dominant under each method. Avicennia germinans was second in relative dominance, Laguncularia racemosa a close third while Conocarpus erectus was rarely found, most likely due to over-harvesting. Rapid degradation of mangrove forests is occurring on a global scale. Understanding the complex dynamics that occur within the mangrove meta-community is essential to its conservation. Vegetation maps are essential tool in monitoring changes throughout the mangrove but are rarely of sufficient detail for everyday use. Generating highly detailed vegetation maps in a cost-effective and timely manner is an important step for their conservation, particularly in developing countries. This study demonstrates methods and techniques for producing a vegetation map that portrays the level of complexity that exists within the species-poor mangrove environment. This map will be donated to the management team of Parque Nacional Lagunas de Chacahua to better aid in management.