Dissertations / Theses on the topic 'Mangrove diversity'

The key findings of this thesis link mangrove diversity with the diversity of abiotic environments and, for the first time, provides a consistent method for the development of a comprehensive scientific framework for the management of mangrove ecosystems at national level. In Australia (and globally) a lack of information on the different mangrove habitats that support the diverse range of mangrove ecosystems has inhibited both management and conservation of mangrove ecosystems. Currently there is no agreed and commonly used national classification scheme for mangrove information. This gap weakens future conservation and sustainable development of the Australian coastline. This thesis addresses that gap in knowledge. The physical framework of the Australian coast forms the habitat template in which mangrove diversity develops. The key hypothesis examined is that an understanding of the abiotic setting within which mangroves are found markedly improves an understanding of the distribution and diversity of mangrove ecosystems. To test that hypothesis, detailed examination of the four overarching physical drivers that shape the Australian continental edge: geology, physiography, climate and oceanography, was undertaken to create a comprehensive picture of the abiotic coastal environment. This showed that coastal, fluvial, and hydrological processes that lead to coastal landform development form the basis for understanding the various coastal landforms and mangrove habitats developed along the Australian coast. The results demonstrate that physical drivers and coastal process do shape the distribution of mangrove species, and how mangrove vegetation is developed, maintained, changed or lost. Inter‐relationships between these overarching physical drivers provide a classification of Australia’s coast into major coastal sectors, including those which do not support mangroves. To elaborate the results, a description of each sector containing mangroves and the types of mangrove habitats present is provided. Mangrove diversity is not simply variation in floristics (species richness) but also must include structural and physiognomy diversity. An individual species of mangrove may perform various ecosystem roles in different physical settings. This concept is elaborated through constructing eight hypothetical expressions of mangrove diversity examining the changes in mangrove habitats under increasing complexity of tidal and climate influence, showing how the interaction between tidal, climate and environmental gradients results in different mangrove expression around the Australian coast. Building on the interactions between abiotic and biotic diversity, seeking ways and means to improve mangrove conservation in Australia, lead to ideas for the development of a mangrove focused national conservation strategy. A set of three criteria is put forward to identify the significance of mangrove sites globally, nationally and/or regionally (sub‐nationally). Besides these practical approaches, an assessment of each State and Territory’s mangrove management and conservation mechanisms shows the scope of existing policies and conservation strategies, and reveals little coordination of mangrove conservation or management issues at the national level, or between the jurisdictions. Building on these findings, and in the framework of the proposed national conservation strategy, a series of recommendations are made to improve the collection and access to mangrove information, including through the implementation of a national level data and information plan providing standards for biophysical and management information on mangroves.

With only around 80 species globally, mangroves generally support low local tree species diversity while sustaining significant ecosystem services. The relationship between biodiversity and ecosystem function in mangroves has rarely been studied, especially when related to local forest diversity. The interdependence between biodiversity and function is important to healthy and functional mangrove ecosystems. Among the many functions of mangroves, juvenile nekton are known to utilize mangroves as their nursery habitat but the justification for this association is not clearly understood. Different plant species are expected to produce different quality of organic content derived from their respective decomposed leaf litter. These leaf litters, which mix into surrounding sediments, are expected to contain different carbon to nitrogen ratios and specific secondary metabolites, influencing its quality. Information on how organic content quality affects the juvenile nekton assemblages in mangroves is limited. This thesis assessed these questions quantitatively, using both field experiments and a laboratory experiment. The aim of this study was to enhance our understanding on how mangrove forests of different local species diversity (mixed forest of Avicennia marina and Rhizophora stylosa and monospecific forests of the two species) can affect the leaf litter decomposition rate, organic content and organic content quality in the sediment, including their adjacent mudflats. This information was then used to assess if the organic content quality from decomposing leaves and sediment influenced the juvenile nekton and invertebrate assemblages associated with the forest stands. The influence of the structural complexity in terms of root density of different forests on the juvenile nekton and invertebrate assemblages was also assessed. Finally, the influence of local tree diversity on the micro-habitat selection by the juvenile caridean shrimp (Palaemon debilis) was investigated in a laboratory choice experiment. Sampling of juvenile nekton and invertebrates was done in three mangrove forests at three locations in the wet and dry seasons in eastern Australia using the Simulated Aquatic Microhabitat (SAMs) method (Kneib, 1997). The animals’ assemblages in the three mangrove forests were characterized and quantified. For each forest, (i) the decomposition rate of A. marina and R. stylosa leaves; (ii) the relationship between animal assemblages and the organic content quality in the sediment; (iii) the relationship between animal assemblages and the structural complexity (root density); and (iv) the relationship between the isotopic signatures of the animal assemblages and the isotopic signatures of the forests were investigated. Juvenile nekton and invertebrate assemblages were highly variable among replicate samples, among different locations, forest types and seasons. The organic content of decomposing leaves and sediment, as well as the structural complexity in terms of root density, also varied spatially. While the factor location was a significant driver of the differences, the effect of forest types (local forest diversity) did not show a similar pattern across locations. The pattern also varied between the mangrove and mudflat habitats. For the decomposition study, it was anticipated that both A. marina and R. stylosa leaves would decompose faster in the mixed forest, however, there was no significant difference in the decomposition rates of the two species in different habitats. In mangrove habitats, sediment organic content was higher in the monospecific R. stylosa forest compared to the mixed forest and monospecific A. marina forest. However, in mudflat habitats significant difference in sediment organic content was only found when adjacent to monospecific R. stylosa forests or mixed forests. In mangrove habitats, the sediment was of lower quality in the mixed forest than in the R. stylosa forest. However, in mudflat habitats, there was no difference between the mixed and monospecific forests. The abundance of juvenile fish and invertebrates was higher only in the mangrove habitat of the mixed forest but not on the adjacent mudflat. In mangrove habitats, the number of species per family and species richness showed significant differences between the mixed forest and both monospecific R. stylosa and A. marina forests. In mangrove and mudflat habitats, Spearman’s rho showed that sediment quality was not related to animal abundance. The quality of decomposed leaf litter was higher in the mixed forest except for A. marina leaves in the adjacent mudflat. As expected, the quality of decomposed leaf litter improved over the decomposition time for all forest types in both habitats. Irrespective of forest type, animal abundance was not related to root density. However, based on location, Spearman rho showed that root density in Tallebudgera Creek was related to animal abundance in all forest types. Animal abundance related to root density during the wet season was related to mixed forest and monospecific Avicennia marina forest. Therefore, local forest diversity showed no clear influence in the relationship between animal abundance to both sediment quality in both habitats and root density in mangrove habitats. The δ13C of the leaves of A. marina and R. stylosa was generally different from those of the animals. Even though the mudflat adjacent to the mixed forest had higher quality of decomposed leaf litter (R. stylosa only), it was unrelated to the animal abundance and assemblages. The δ13C of R. stylosa leaves was close to the δ13C of one of the fish species from the same forest and this indicates R. stylosa potentially contributed to the diet of this fish. Results of the laboratory choice experiment indicated that the identity of mangrove forests influenced micro-habitat selection in the juveniles of Palaemon debilis. This response is probably mediated by olfactory cues from the mangrove leaf litter. This study is the first to show that P. debilis is able to detect and distinguish water-borne chemical cues from three different types of mangrove leaves. The chemicals released by the leaf litter of R. stylosa apparently acted as a positive cue that attracted the juvenile shrimps.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

Mangroves are a group of woody plants that occur in the dynamic tropical and subtropical intertidal zones. Mangrove forests offer numerous ecosystem services (e.g. nutrient cycling, coastal protection and fisheries production) and support costal livelihoods worldwide. Rapid environmental changes and historical anthropogenic pressures have turned mangrove forests into one of the most threatened and rapidly vanishing habitats on Earth. Yet, we have a restricted understanding of how these pressures have influenced mangrove abundance, composition and functions, mostly due to limited availability of mangrove field data. Such knowledge gaps have obstructed mangrove conservation programs across the tropics. This thesis focuses on the plants of Earth’s largest continuous mangrove forest — the Sundarbans — which is under serious threat from historical and future habitat degradation, human exploitation and sea level rise. Using species, environmental, and functional trait data that I collected from a network of 110 permanent sample plots (PSPs), this thesis aims to understand habitat preferences of threatened mangroves, to explore spatial and temporal dynamics and the key drivers of mangrove diversity and composition, and to develop an integrated approach for predicting functional trait responses of plants under current and potential future environmental scenarios. I found serious detrimental effects of increasing soil salinity and historical tree harvesting on the abundance of the climax species Heritiera fomes. All species showed clear habitat preferences along the downstream-upstream gradient. The magnitude of species abundance responses to nutrients, elevation, and stem density varied between species. Species-specific density maps suggest that the existing protected area network (PAN) does not cover the density hotspots of any of the threatened mangrove species. Using tree data collected from different salinity zones in the Sundarbans (hypo-, meso-, and hypersaline) at four historical time points: 1986, 1994, 1999 and 2014, I found that the hyposaline mangrove communities were the most diverse and heterogeneous in species composition in all historical time points while the hypersaline communities were the least diverse and most homogeneous. I detected a clear trend of declining compositional heterogeneity in all ecological zones since 1986, suggesting ecosystem-wide biotic homogenization. Over the 28 years, the hypersaline communities have experienced radical shifts in species composition due to population increase and range expansion of the disturbance specialist Ceriops decandra and local extinction or range contraction of many endemics including the globally endangered H. fomes. Applying habitat-based biodiversity modelling approach, I found historical tree harvesting, siltation, disease and soil alkalinity as the key stressors that negatively influenced the diversity and distinctness of the mangrove communities. In contrast, species diversity increased along the downstream – upstream, and riverbank — forest interior gradients, suggesting late successional upstream and forest interior communities were more diverse than the early successional downstream and riverbank communities. Like the species density hotspots, the existing PAN does not cover the remaining biodiversity hotspots. Using a novel integrated Bayesian modelling approach, I was able to generate trait-based predictions through simultaneously modelling trait-environment correlations (for multiple traits such as tree canopy height, specific leaf area, wood density and leaf succulence for multiple species, and multiple environmental drivers) and trait-trait trade-offs at organismal, community and ecosystem levels, thus proposing a resolution to the ‘fourth-corner problem’ in community ecology. Applying this approach to the Sundarbans, I found substantial intraspecific trade-offs among the functional traits in many tree species, detrimental effects of increasing salinity, siltation and soil alkalinity on growth related traits and parallel plastic enhancement of traits related to stress tolerance. My model predicts an ecosystem-wide drop in total biomass productivity under all anticipated stress scenarios while the worst stress scenario (a 50% rise in salinity and siltation) is predicted to push the ecosystem to lose 30% of its current total productivity by 2050. Finally, I present an overview of the key results across the work, the study’s limitations and proposals for future work.

The mangrove forest is an ecosystem distributed worldwide along tropical andsubtropical coastlines. The environmental conditions are known to affect species distributionpatterns, and to understand them is one of the main goals of biogeography. The association ofenvironmental factors (e.g. temperature and precipitation) and species distribution patterns haschallenged scientists since long. Species are distributed in a geographical space, however, whyspecies are present in a certain location but absent in another is a fundamental question inbiogeography. This PhD thesis aims at better understanding the most intriguing issues relatedto the role of environmental factors associated with mangrove distribution range limits andspecies richness from regional (Brazilian mangroves) to global scales.For the Brazilian mangroves, two scales were used to comprehend the spatial ecological nicheof mangrove tree species. First, the entire Brazilian mangrove-lined coast was considered, andseveral environmental variables were used to explain what is driving mangrove tree speciesdistribution. Second, a detailed analysis of daily Sea Surface Temperature (SST) data for theBrazilian mangrove forest at the southernmost mangrove range limit was done, and comparedwith a site beyond the range limit. The chilling events of SST data, also considering oceancurrents, show that Laguncularia racemosa is probably bounded by the southernmost Brazilianmangrove limit because of a dispersal constraint rather than by the frequency of chillingevents. However, the abundance of L. racemosa in Laguna at the Southern mangrove rangelimit, compared with only a few individuals of A. schaueriana, is probably associated with thechilling events of SST constituting a constraint to the latter species. This proves that mangroverange limits are not explained by a single causeThis PhD thesis also has the objective to evaluate the influence of upwelling intensity onthe distribution worldwide, which is its approach at a global scale. The sea surface temperature(SST) had been identified as one of the key drivers of global mangrove distribution, given thecoincidence of isotherms with mangrove global limits. However, other factors play a role in thevariability of SST. Cold waters from deep ocean layers rise to the surface (upwelling systems),which reduces SST values and can trigger aridity. Although previous research has confirmedthat mangrove distribution is driven by a variety of factors, this PhD thesis additionallydemonstrates a significant influence of upwelling intensity, and hence provides elements for abetter understanding of the factors driving mangrove expansion/retraction at a global scale. Inaddition, this work emphasizes climate and oceanographic processes influencing mangroverange limits. While contributing to a better understanding of some of the most intriguingquestions on the macroecology of mangrove, this PhD thesis also raises new questions thatshould be studied by future research.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

L'amélioration des processus de dégradation de la biomasse lignocellulosique est un enjeu capital du développement des biotechnologies vertes. Au cours de ces travaux de thèse, nous nous sommes intéressés à deux sujets centrés autour de l'exploitation des souches fongiques pour la dégradation de la lignocellulose. Tout d'abord, nous avons étudié la diversité taxonomique et enzymatique d'un environnement original : la mangrove. Une campagne de prélèvement en Nouvelle-Calédonie à été organisée, afin d'étudier la diversité taxonomique des communautés fongiques établies sur les palétuviers. L'utilisation d'une approche « Tag-Pyrosequencing » a permis de mettre en lumière l'existence d'une taxonomiques extrêmement importante puisque plusieurs milliers d'espèces ont été détectées dans les différentes niches écologiques de cet écosystème. Ces travaux ont également permis d'établir le rôle primordial de la spécificité d'hôte dans l'établissement des communautés fongiques. Nous avons par la suite isolé différentes souches de champignons à partir d'échantillons de palétuvier et avons procédé au criblage de leurs activités lignocellulolytiques (oxidase, cellulase, mannanase, xyalanase). A l'issue de ce crible, une souche, identifiée comme un Pestalotiopsis sp, présentant la plus grande polyvalence en termes d'activités enzymatiques a été sélectionnée
The improvement of lignocellulosic biomass degradation processes is a key aspect of the development of “green” biotechnologies. During this thesis, we focused on two subjects centred on the usage of fungal strains for the degradation of lignocellulose. First, we studied the taxonomic and enzymatic diversity in an original ecosystem: mangroves. A sampling was performed in New-Caledonia in order to study the fungal communities colonizing mangrove trees. By using Tag-Pyrosequencing, we showed the existence of very large communities harbouring several thousand species in the different microhabitats of the ecosystem. This work also revealed the key role of host specificity as a factor driving the fungal colonisation of mangrove trees. We then isolated several fungal strains from various mangrove tree samples, and performed a screening of their lignocellulolytic activities (oxidase, cellulase, mannanase, xylanase). A single strain was selected fromthis screening, identified as Pestalotiopsis sp., which showed the most complete diverse enzymatic activities. A de novo transcriptome was assembled from mRNA sequences, which allowed highlighting a wide array of transcripts encoding biomass degradation enzymes, as well as the existence of a mechanism of adaptation to salt based on the secretion of salt-tolerant lignocellulolytic enzymes. Secondly, we studied the limitations of fungal co-culture linked to competitive interactions mechanisms. The RNA-Seq analysis of genetic expression during the interaction between Pycnoporus coccineus and Coniophora puteana or Botrytis cinerea indicates that different mechanisms are used depending on the opponent

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.

En contexte équatorial, les sédiments intertidaux sont colonisés par un continuum écologique allant de vasières en cours de stabilisation à des sols colonisés par divers faciès de mangroves. Les fonctions microbiennes édaphiques de ces écosystèmes sont méconnues. Ces recherches ont donc eu pour objectif de définir les facteurs de contrôle et de variabilité spatio-temporelle des fonctions microbiennes des milieux estuariens et littoraux de Guyane française. Elles ont été conduites sur divers stades de colonisation biologique de ces habitats et à diverses échelles spatio-temporelles en tenant compte du rôle de l'instabilité hydro-sédimentaire et des variabilités induites par les saisons hydro-climatiques. Différents facteurs pouvant influencer les fonctions microbiennes ont été considérés : i) la qualité chimique (RMN solide du 13C) de la MOS en fonction de la composition des formations végétales et de leurs stades de développement ; ii) les caractéristiques physico-chimiques des sédiments et des eaux interstitielles en fonction de la localisation des divers faciès de mangroves. Les résultats ont mis en évidence l'importance des instabilités hydro-sédimentaires dans la mise en place et la structuration des fonctions microbiennes sédimentaires de Guyane. En outre, pour les différents modèles étudiés, les facteurs de structuration sont apparus variables. Néanmoins, la MO, en termes de quantité et de qualité, s'est révélée être un facteur prépondérant pour l'expression de ces fonctions des stades allant de la vasière nue à la jeune mangrove. En revanche, il est apparu plus difficile de discerner des facteurs structurants génériques pour les divers faciès de mangroves matures
Under equatorial conditions, coastal sediments of intertidal mudflats form an ecological continuum, from bare mud being stabilized to soil settled by various mangrove facies. Edaphic microbial functions of terrestrial ecosystems are extensively documented; on the contrary, this is not the case with regards to sedimentary environment. This study had the main objective defining the drivers of the spatiotemporal variability of microbial functions (aerobic respiration, metabolic diversity, and enzyme activities) in coastal sediments of French Guiana. These researches were carried out according to biological colonization states (mudflats, pioneer and mature mangroves) and using various spatiotemporal scales considering the fundamental role of the hydro-sedimentary instability and potential variability due to hydro-climatic seasons. Different factors which can influence microbial functions were studied: i) the chemical quality (13C solid-state NMR) of OM with respect to vegetation presence and composition, and its development state; ii) the physicochemical characteristics of sediments and porewaters according to localization and topography of the different mangrove facies. Generally, results showed the importance of hydro-sedimentary instability for the establishment and structuring of microbial functions. Moreover, giving the different models, structuring factors were variables. However, OM, in terms of quantity and quality, was overriding for the expression of these functions and this was true for the evolution states from mudflat to young mangrove. By contrast, it appeared much more difficult discerning generalizable drivers for mature mangroves

The role of mangroves as essential fish habitat has been a focus of extensive research. However, recent evidence has shown that this role should not be evaluated in isolation from surrounding habitats such as seagrass beds and hard-bottom communities. For example, submerged aquatic vegetation (SAV) communities provide potential sources of food and shelter for fish species that may reside in the mangroves, but may also undergo ontogenetic migrations and daily home-range movements into neighboring habitats. The connectivity between the mangrove fish community and the surrounding seascape may be influenced by the level of patchiness, fragmentation, and spatial heterogeneity of adjacent SAV habitats (i.e., SAV seascape structure). The spatial patterns and heterogeneity of SAV seascape structures are driven by internal and external regulatory mechanisms operating at different spatial and temporal scales. In addition, it is likely that many fish species inhabiting the mangrove zones have different home ranges, and foraging and migratory patterns; therefore, different mangrove fish species may respond to seascape heterogeneity at different scales. There are few studies that have assessed the influence and connectivity of benthic habitats adjacent to mangroves for estuarine fish populations at multiple scales. The present research used an exploratory seascape approach in Biscayne Bay (Florida, USA) to evaluate patterns in the patch composition and configuration of SAV communities, and to examine relationships between seascape structural metrics and the abundance, diversity, and distribution of fishes that utilize the adjacent mangrove shoreline as nursery and/or adult habitat. This seascape approach consisted of: a) the multi-scale characterization of the SAV distribution across the seascape with metrics developed in Landscape Ecology, Geographic Information Systems and Remote Sensing; b) multivariate analyses to identify groups with significantly distinct SAV seascape structures within the most heterogeneous scale, and identify possible mechanisms driving the observed SAV seascape structures; and c) an assessment of the mangrove fish community responses to SAV seascape structures. By applying a set of multivariate analyses (e.g., ANOSIM, MDS plots, hierarchical clustering), the buffer within 200 m from shore was identified as the scale with the highest structural heterogeneity. At this scale, two major SAV seascape structures (i.e., areas with similar SAV spatial arrangement and composition) were identified: a fragmented SAV seascape (FSS) structure and a continuous SAV seascape (CSS) structure. Areas with CSS were characterized by large, uniform SAV patches. In contrast, areas with FSS were characterized by a higher density of smaller, more complex SAV patches. Furthermore, the areas with CSS and FSS structures clustered in zones of the bay with distinct salinity properties. The areas with CSS structures were mostly located in zones characterized by high and stable salinity. However, the areas with FSS concentrated in zones that are influenced by freshwater discharges from canals and with low and variable salinity. The responses of fish diversity metrics were not constrained to the scale at which the greatest spatial heterogeneity of SAV seascape structures was observed (i.e., the seascape composition and configuration within 200 m from shore), but was related to SAV seascape characteristics across different scales. The majority of the variability of the fish diversity metrics in the mangrove shoreline was explained by SAV seascape structures within the smaller scales (i.e., 100-400 m from shore), and SAV seascape structures that represented the level of fragmentation and/or the percent of suitable habitat. Different conceptual models were proposed to illustrate and understand the ecological dynamics behind the relationship between the diversity of the mangrove fish community and the structure of the adjacent SAV seascape. In general, the diversity and abundance of fishes is influenced by the type and level of fragmentation of the SAV seascape, which, in turn, influence the proportion of the seascape used for foraging and refuge by fish. In conclusion, this research quantified how the release of large pulses of freshwater into near-shore habitats of coastal lagoons can influence the seascape structure of SAV communities. Namely, freshwater inputs produce fragmentation in otherwise fairly homogeneous SAV meadows. The outcome of this research highlights the importance of seascape characteristics as indicators of ecosystem-level modifications and alterations affecting the spatial distribution, assemblage, and diversity of marine nearshore habitats in coastal regions heavily influenced by human activities. In addition, the results illustrated the cascading effects and synergistic influences of near-shore habitat spatial assemblages on the composition and diversity of estuarine fish communities. Lastly, and very importantly, the relationships established in this project provide quantitative and qualitative information on patterns of species-habitat associations needed for the improved synergistic management and protection of coastal habitats and fisheries resources.

Estudos sobre a diversidade de Bacteria em solos de mangue (Brasil) e marisma (Espanha) são escassos. A vegetação de mangue, composta por espécies como Spartina alterniflora, Rhizophora mangle, Avicennia schaueriana e Laguncularia racemosa, pode ser um dos fatores que determinam a estruturação das comunidades de procariotos. Determinações das estruturas das comunidades e de diversidade de Bacteria podem ocorrer em função das diferentes condições físico-químicas dos solos, refletindo na configuração dos processos biogeoquímicos. O objetivo deste trabalho foi avaliar a variação das estruturas das comunidades de Bacteria e Archaea, bem como a diversidade, em solos de mangue e marisma utilizando DGGE e sequenciamento parcial do rDNA 16S. As estruturas das comunidades de procariotos apresentaram variações em função de condições de vegetação. Proteobacteria e Bacteroidetes estão presentes em todos os solos estudados. A comunidade de Bacteria destes ambientes é dominada por Proteobacteria. Vários dos táxons detectados estão relacionados com ciclos biogeoquímicos importantes para os ambientes estudados. As estimativas não-paramétricas de riqueza de espécies (ACE e Chao1) mostram que solos de mangue e marisma podem conter milhares de espécies de bactérias. As comunidades de Bacteria dos solos de mangue e marisma são significativamene diferentes. Na camada mais superficial do sedimento de mangue predomina Euryarchaeota metanogênicas enquanto que na camada mais profunda predomina Crenarchaeota. Bactérias das ordens Desulfobacterales, Desulfovibrionales e Desulfuromonales podem estar relacionadas com a atividade de sulfato-redução e formação de pirita na camada anaeróbia do perfil de solo de marisma. De uma maneira geral, pode-se concluir que a diversidade e estrutura das comunidades de procariotos de ambientes estuarinos pode variar em função da vegetação estabelecida e do tipo de ambiente. Adicionalmente, solos de mangue e marisma possuem grande diversidade de procariotos, grande parte da qual é desconhecida, podendo representar elevado potencial genético para utilização biotecnológica.
The bacterial diversity in mangrove (Brazil) and marisma (Espanha) soils are largely unknown. Bacterial communities participate in biogeochemicals processes that occurs in soils of estuarine ecosystems. Determinations of the bacterial communities structures and diversity can occur in function of different physico-chemical conditions, reflecting in the biogeochemical processes. The aim of this work was to evaluate the variation of bacterial an archaeal communities structures utilizing DGGE and partial sequencing of 16S rDNA. Bacterial community structures showed more similarity between repetitions samples than the areas under different vegetation. Phylogenetic afiliation shows that several sequences were not clamped into known phyla. Proteobacteria prevails in bacterial communities of mangrove and marisma soils. Several taxa detected are associated to important biogeochemical cycles that occur in estuarine ecosystems. Analysis of species richness showed that mangrove and marisma soils can contain 200 to 6000 species of bacteria. Methanogenic Euryarchaeota was found specially in the upper sample of mangrove sediment analysed whereas the Crenarchaeota was found specially in the lower. Based on the data obtained, it can be concluded that the vegetation is one of the factors affecting the structure of bacterial and archaeal communities in mangrove soils. Additionaly, the effects of edafic factors and seasonal variations have to be considered as determining the prokaryotic community sctuctures, and bacterial and archaeal communities can respond independently to the factors that determine their community structures. Bacterial diversity can vary with the studied estuarine ecosystem. Studies are necessary concerning to diversity of Bacteria, it variation and correlation with biogeochemical process in the mangrove and marisma soils. These soils show a great diversity of bacteria, much of than unknown, which represent a great genetic potential to the biotechnology.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Os manguezais sÃo ecossistemas costeiros que ocorrem em regiÃes de clima tropical e subtropical, sujeitos a aÃÃo das marÃs. SÃo regiÃes de extrema importÃncia para a reproduÃÃo de espÃcies, atuam como aparadores da linha da costa e possuem espÃcies vegetais endÃmicas, conhecidas como mangue. Os manguezais geralmente sÃo Ãreas bastante populosas, estando sujeitos a diversos impactos antrÃpicos, como a descarga de esgotos nÃo-tratados, o desmatamento das espÃcies vegetais e assoreamento dos rios. Esses impactos afetam as populaÃÃes de animais, vegetais e de micro-organismos habitantes dessas Ãreas, acarretando uma perda de diversidade desses organismos. Os micro-organismos do solo dos manguezais representam uma considerÃvel parcela das atividades de ciclagem de nutrientes e decomposiÃÃo de detritos, tendo fundamental importÃncia para o equilÃbrio dos ecossistemas. Entretanto, estudos de diversidade e estrutura dessas comunidades de micro-organismos em solos de manguezais sÃo ainda escassos pela dificuldade de cultivo desses seres em laboratÃrio. Com o avanÃo da biologia molecular, suas tÃcnicas de estudo de diversidade utilizando o gene do rRNA 16S, houve a oportunidade de se estudar comunidades microbianas que nÃo seriam acessadas por mÃtodos de cultivos tradicionais. Deste modo, este estudo visa investigar a estrutura e a diversidade das comunidades microbianas do solo da rizosfera de Rhizophora mangle do manguezal do Rio Pacoti, localizado na regiÃo metropolitana de Fortaleza, atravÃs da tÃcnica de Eletroforese em Gel de Gradiente Desnaturante (DGGE), assim podendo obter perfis de diversidade e caracterizar as comunidades microbianas habitantes do manguezal, compararando os dados obtidos com as variÃveis ambientais e caracterÃsticas do solo. Os resultados mostraram que as comunidades microbianas de solos do manguezal sÃo semelhantes em nÃmero de UTOs, mas diferem em composiÃÃo. As variÃveis fÃsico-quÃmicas e as caracterÃsticas do solo sÃo responsÃveis pelas diferenÃas na composiÃÃo e estrutura das comunidades microbianas, apesar de que o efeito rizosfÃrico determina a ocorrÃncia de muitas UTOs em comum entre os diferentes pontos de coleta. As anÃlises de diversidade das comunidades mostraram que estas estÃo em equilÃbrio por nÃo haver dominÃncia de UTOs e por apresentarem similaridades entre os pontos e perÃodos analisados. Em conclusÃo, os solos da rizosfera de Rhizophora mangle do manguezal do Rio Pacoti abrigam comunidades microbianas diversas, em equilÃbrio, que diferem em estrutura e composiÃÃo
Mangroves are coastal ecosystems which occur in tropical and subtropical regions, subjected to tidal action. These ecosystems are very important for species reproduction and act as shoreline protectors. Mangroves are usually highly populated areas and are exposed to various human impacts, such as the discharge of untreated sewage, deforestation and river silting. These impacts affect populations of animals, plants and microorganisms that inhabit these areas, causing a loss of diversity. The mangrove soil microorganisms represent a considerable portion of the activities of nutrient cycling and decomposition of waste with a fundamental importance for the ecosystem balance. However, studies focusing on the diversity and structure of microorganism communities in mangroves soils are still limited by cultivation techniques. With the advance of the molecular biology techniques, using the gene encoding the 16S subunit of the ribosomal RNA, the study of microbial communities that would not be accessed by traditional methods of cultivation was enabled. Thus, this study aims to investigate the structure and diversity of soil microbial communities from the rhizosphere of Rhizophora mangle from the Pacoti River, located in the metropolitan region of Fortaleza, using Denaturing Gradient Gel Electrophoresis (DGGE), obtaining diversity profiles and characterizing the mangrove microbial communities and to compare it to the data obtained from the environmental variables and soil characteristics. Results showed that the mangrove soils microbial communities are similar in number of OTUs, but differ in composition. The physical and chemical variables and soil characteristics are responsible for the differences in the microbial communities‟ composition and structure, although the rhizosphere effect determines the occurrence of various OTUs in common among the sampling sites. The communities‟ diversity analysis showed that they are in balance due to the fact that there is no dominance of OTUs and the communities present spatial and temporal similarities. In conclusion, the Rhizophora mangle rhizosphere soils of the Pacoti River mangrove harbor diverse and stable microbial communities that differ in structure and in composition

Os impactos da poluição por hidrocarboneto de petróleo sobre a diversidade e funcionalidade das comunidades microbianas em manguezais não são totalmente conhecidos, principalmente devido às limitações metodológicas para acessar os microrganismos nãocultiváveis. No entanto, vários métodos moleculares independentes de cultivo têm sido utilizados para investigar a diversidade e a estrutura das comunidades microbianas em ecossistemas naturais. O objetivo deste trabalho foi avaliar as variações da estrutura das comunidades de Bacteria e Archaea e a diversidade de Bacteria em uma transeção de solo de mangue do rio Iriri (Bertioga, SP) com um gradiente de contaminação por hidrocarbonetos de petróleo. As análises por eletroforese em gel com gradiente desnaturante (DGGE) mostraram que as comunidades de Bacteria e Archaea nas diferentes posições geográficas foram mais similares entre si do que entre diferentes profundidades ao longo do perfil em uma mesma posição geográfica. A análise das seqüências de clones de rDNA 16S de Bacteria dos diferentes pontos amostrados em abril de 2000, mostrou que a diversidade genética, avaliada pelo índice de Shannon, das comunidades microbianas diferem estatisticamente somente entre ponto o P1 (ponto menos contaminado) e P3 (ponto mais contaminado). As estimativas não-paramétricas da riqueza de espécies mostraram que P1, P2 e P3 possuem mais de 3539, 2524 e 1421 espécies bacterianas, respectivamente. Já, para as amostras do ponto P2 coletadas nos anos 2000 e 2004, muito embora os valores dos índices de Shannon tenham sido semelhantes, houve uma provável dominância de grupos específicos nas amostras coletadas em 2004, verificada pelos altos valores da recíproca do índice de Simpson. Os dados mostraram também que o número estimado de espécies bacterianas no ponto P2 diminuiu com o tempo, sendo menor em amostras de 2004, se comparado com amostras de 2000. No geral, a afiliação filogenética dos clones de rDNA 16S mostrou a grande diversidade de espécies, a maioria não conhecidas. Os dados sugerem que a contaminação do solo de mangue do rio Iriri está selecionando microrganismos mais adaptados às fontes de carbono introduzidas no solo.
The impacts of petroleum hydrocarbon pollution on the diversity and functionality of the microbial communities in mangrove soils are not totally understood, mainly due to the methodological limitations to access unculturable microorganisms. However, several cultureindependent molecular methods have been used to investigate the diversity and structure of microbial communities in natural ecosystems. The aim of this work was to evaluate shifts in Bacteria and Archaea community structures and the diversity of Bacteria in a soil transection of the Iriri river mangrove (Bertioga, SP) showing a petroleum hydrocarbon contamination gradient. The analyses by denaturing gradient gel electrophoresis (DGGE) showed that the communities of Bacteria and Archaea in different geographical positions were more similar among them than the communities in different depths along the soil profile at the same geographical position. Sequence analyses of bacterial 16S rDNA clones from different points sampled in April 2000 showed that the genetic diversity of the bacterial communities, based on the Shannon index, differ statistically only between P1 (less polluted) and P3 (more polluted) locations. Nonparametric estimates of species richness showed that P1, P2 and P3 may have more than 3539, 2524 and 1421 bacterial species, respectively. For P2 sampled in years 2000 and 2004, even though the Shannon indices were similar, there was a probable dominance of specific bacterial groups in year 2004, based on the high values of the reciprocal of Simpson\'s index. The data also showed that the estimated number of bacterial species in P2 decreased with the time, being lower in samples collected in 2004, as compared to samples collected in 2000. In the general, the phylogenetic affiliation of the 16S rDNA clones showed high bacterial species diversity, and most of the bacteria were of unknown species. The data suggest that the contamination of Iriri river mangrove soil with petroleum hydrocarbon is selecting microorganisms more adapted to the introduced carbon sources into the soil.

Manguezais são ecossistemas localizados na confluência de terra e mar, característicos de áreas tropicais e subtropicais, cobrindo cerca de 18,1 milhões de hectares do planeta. A grande biodiversidade encontrada nestes ambientes ressalta a importância da busca por conhecimentos à seu respeito, como o estudo sobre novos princípios ativos derivados de microrganismos endofíticos presentes nas plantas de manguezais. Desta forma, o propósito do presente trabalho foi determinar a diversidade genética da comunidade de fungos endofíticos presentes em folhas e ramos das principais espécies arbóreas de manguezais de Cananéia e Bertioga (situados no estado de São Paulo, Brasil), e avaliar o potencial biotecnológico destes fungos em relação à produção de antibióticos contra os patógenos humanos Staphylococcus aureus e Escherichia coli, e contra o fitopatógeno Xanthomonas axonopodis citri . Os resultados da primeira etapa do trabalho, que envolveu o isolamento e a caracterização de fungos endofíticos filamentosos, mostraram que a comunidade fúngica associada às plantas de manguezais é formada por pelo menos 35 gêneros diferentes, sendo que os gêneros mais frequentes foram Diaporthe, Fusarium, Trichoderma, Colletotrichum e Xylaria. Grande parte dos gêneros encontrados neste trabalho é de fungos de solo, indicando que eles estão adaptados às condições adversas dos manguezais. Os resultados mostraram que, dentre as linhagens produtoras de antibiótico, 29,41% pertencem ao gênero Diaporthe, o qual apresentou maior frequência na comunidade fúngica estudada. Após a avaliação de 344 fungos quanto ao potencial de atividade antimicrobiana, foi selecionada a linhagem 41.1(1) de D. phaseolorum, um endófito de folha de Laguncularia racemosa, para elucidação da estrutura química do seu antibiótico purificado. Por meio das técnicas de Ressonância Magnética Nuclear e de Espectrometria de Massas o antibiótico foi identificado como ácido 3-hidroxipropiônico o qual apresentou atividade frente aos patógenos humanos Staphylococcus aureus e Salmonella tiphy. A estrutura química deste antibiótico foi modificada por meio de reação química de esterificação de Fischer-Speier para avaliar a relação da estrutura química e atividade biológica deste composto. O produto final da reação química de esterificação do antibiótico ácido 3-hidroxipropiônico não apresentou atividade antimicrobiana, indicando que o grupo hidroxila removido na reação é importante na atividade farmacológica desse composto. Além disso, a linhagem 41.1(1) de D. phaseolorum foi transformada geneticamente pelo sistema Agrobacterium tumefaciens, visando a obtenção de transformantes deficientes para produção de antibiótico e, com isso, a identificação de genes relacionados com a via de biossíntese do antibiótico ácido 3-hidroxipropiônico. A análise das sequências que flanqueiam o T-DNA, obtidas por TAIL-PCR, mostraram que os genes interrompidos nos transformantes estão relacionados com proteínas de domínios conservados envolvidos com diferentes funções como: translação de proteínas, homeostase do íon orgânico Mg2+, transporte intracelular, migração, adesão e proliferação celular e outras funções celulares. A caracterização da biblioteca de agrotransformantes constitui uma ferramenta importante para o estudo da biologia molecular de fungos que produzem compostos bioativos por meio do seu metabolismo secundário.
Mangroves are ecosystems situated beyond land and sea. They are more frequently found in tropical and subtropical areas englobing around 18.1 millions of hectares in the planet. The great biodiversity found in these ecosystems shows the importance of researching them, including studies regarding new compounds derived from endophytic fungi that inhabit these ecosystems. Therefore, the goal of this study was to determine the genetic diversity of the fungal endophytic community found in leaves and branches of the main arboreal species from mangrove of Cananéia and Bertioga (situated in São Paulo state, Brazil), and to evaluate the biotechnological potential of these fungi concerning the production of antibiotics against the human pathogens Staphylococcus aureus and Escherichia coli, and against the phytopathogen Xanthomonas axonopodis citri . The results of the first part of this work, including the isolation and characterization of the filamentous endophytic fungi, showed that the mangrove fungal community is made up of at least 35 different genera, from which the most frequent are Diaporthe, Fusarium, Trichoderma, Colletotrichum and Xylaria. Most of the fungal genera found in this study come from soil, which suggests that they are adapted to the adverse conditions of mangroves. The results show that among the antibiotic-produncing strains, 29.41% belong to the genus Diaporthe, which was the most frequently found in the studied fungal community. After the analysis of 344 fungi regarding the antibiotic activity potential, a strain of D. phaseolorum (a leaf endophyte of Laguncularia racemosa) was selected to unveil the chemical structure of their purified antibiotic. The nuclear magnetic resonance and the mass spectrometry techniques allowed the identification of the antibiotic as 3-hidroxypropionic acid, which displayed activity against the pathogens Staphylococcus aureus and Salmonella tiphy. The chemical structure of this antibiotic was modifyed by the chemical reaction of Fischer-Speier sterification in order to evaluate the chemical structure and biological activity of this compound. The final product of the chemical reaction of 3-hidroxipropionic acid sterification had no antibiotic activity, which suggests that the hydroxil group removed from the reaction is important to the pharmachological activity of this compound. Additionally, the strain 41.1(1) of D. phaseolorum was genetically transformed by the Agrobacterium tumefaciens system, in order to generate antibioticdeficient transformants, which would help to identify genes related to the biosynthesis pathway of the 3- hidroxypropionic acid antibiotic. The TAIL-PCR analysis revealed that the interrupted genes in the tranformants are related to proteins from conserved domains involved in different functions such as protein translation, Mg2+ ion homeostasis, intracellular transport, migration, adhesion and cellular proliferation and other cellular functions. The characterization of the agrotransformants library is an important tool to unveiling the molecular biology of fungi that produce bioactive compounds by the secondary metabolism.

Rates of loss of biodiversity caused by human action are on the increase worldwide. However implications of species loss on the natures' ability to provide ecosystem services and goods are still poorly understood. Despite providing an array of critical services and goods, mangrove ecosystems are under intense threat. In attempts to address the problem, several mangrove restoration initiatives have been formulated in many areas of the world with different objectives. Over the last two decades, experiments manipulating species diversity and measuring ecosystem functions have been conducted mainly using grassland ecosystems and have exhibited positive relationships. More recently, experiments investigating this relationship have emerged in longterm woody species i.e. trees; however these have concentrated on terrestrial forests. This study experimentally manipulated different mangrove species and measured a range of ecosystem functions including sapling survival, above and below ground biomass production and sediment C02 efflux. Enhanced sapling growth was positively correlated with plot height above datum, percentage silt and nitrates and negatively correlated with sediment salinity, ammonium and phosphates. Also high values of above and below ground biomass, root: shoot ratios, mean tree height, leaf area index as well as naturally recruited saplings were observed in mixed plots (particularly with Avicennia marina in the mixture) compared with monospecific plots. Species selection effect, particularly from the fast growing A. marina species was the mechanism behind a range of the observed ecosystem functions. However complementarily effects were observed particularly on above ground biomass. However sapling survival and sediment CO2 efflux was not influenced by species richness. We conclude that there is variation in the stages of plant development at which species richness effects manifest themselves, in addition the effects of environmental variables has a bearing on the nature and direction of the relationship between species richness and ecosystem function. We anticipate changes in the plots structure over time from A vicennia facilitative effects which are expected to lead to changes in sediment microclimate inducing changes in other species growth and promoting recruitment and development of wildlings.

Variation in plant functional traits reflect the differences in an environment a species occupies and the variation in the functional traits across an environmental gradient and growth form reflects the functional performance of the coexisting species. Therefore, detecting the differences in functional traits of species is important to our understanding of the performance of species. The leaf functional traits; Leaf mass per area (LMA) and vein density (DV) are key traits in the resource use strategies and photosynthetic gas exchange capacity (Amax, gsmax) of all plants. Mangroves occupy a hypersaline narrow ecological range and therefore are thought to have uniform functional performance. This view makes sense for low diversity mangrove communities, but what about the hyperdiversity communities such as those in New Guinea? A comprehensive review of the present understanding on the ecology and socio-ecological values of mangrove was undertaken to establish a good foundational understanding of my study on New Guinea mangroves (Chapter 1). It is widely held that mangroves thriving in a hypersaline environment experience high water constraints and as a result have high water use efficiency, therefore have narrow functional performance. I investigated the leaf and photosynthetic functional traits of 31 mangrove species among different zonation bands and growth from six mangrove communities in New Guinea to test the view that mangroves have a narrow functional performance (Chapter 2). I then investigated the differences in wood and stem hydraulic traits among different zonation bands and growth forms and the relationship between wood hydraulics and leaf photosynthetic gas assimilation functional performance to further test the long standing view that mangroves have a narrow functional performance (Chapter 3). I then summarized the major findings of my two studies and their implications on mangrove restoration and rehabilitation with particular reference to the recent mangrove rehabilitation initiatives in Papua New Guinea (Chapter 4). My studies on leaf and wood functional traits across different zonation bands, growth forms and root system types consistently revealed that mangroves have a wide functional performance, and different species exhibited different resource use strategies.

Microorganisms are widespread in all ecosystems and play critical roles in nature. They are major players in global biogeochemical cycles that are fundamental in nutrient cycling. Molecular ecology surveys that investigate the microbial diversity of many different environments have revealed an impressive diversity of microbes in nature and have highlighted our inability to cultivate the vast majority of them in the laboratory. The improvement of our ability to grow uncultivable microbes in laboratory conditions will help us in this challenging task. Standard cultivation methods that have helped to bring to culture many relevant microorganisms in the past century are, however, characterized by limitations which hamper the isolation of novel microbes. For this reason, alternative cultivation strategies have been developed in recent decades which have allowed to expand the collection of environmentally relevant but poorly represented microbial strains. The use of such novel approaches for investigating the microbial diversity of underexplored natural ecosystems, such as sub-tropical mangrove forests, can result in the isolation, in laboratory conditions, of bacterial strains belonging to previously undescribed taxa. Mangroves are unique environments exposed to strong selection forces with respect to other marine environments, including high temperatures, salinity and oligotrophy. I hypothesize that these unique combinations of environmental features have selected microbiomes with unique characteristics. The aim of this PhD research is to explore the bacterial diversity of the Red Sea mangrove ecosystem, by applying an alternative cultivation strategy that uses oligotrophic conditions and long incubation time. I also exploited the diffusion chamber to cultivate bacterial taxa belonging to rarely isolated or even novel genera. This approach allowed me to isolate four novel bacterial taxa. Using 16S rRNA gene sequencing, the isolated bacteria were identified as one novel species and three novel genera belonging to Alpha-proteobacteria, Bacteroidetes, and Firmicutes, respectively. These isolates were further characterized and described through genomic, phylogenetic, chemotaxonomic, and phenotypic analysis to describe their ecological significance in the ecosystem of origin (i.e., mangrove sediments). This study reveals that the extreme conditions of the Red Sea mangroves have selected a unique and yet mostly untapped culturable microbiome with great potential for environmental applications.

碩士
國立東華大學
海洋生物研究所
107
Fungal endophytes have been found to exist in every plant species examined to date and appear to be important to their plant hosts. However, the diversity and antimicrobial activity of this group of fungus are largely unknown. In present research, five leave samples, collected from mangrove plant Acanthus ilicifolius var. xiamenensis at Lesser Kinmen Island, located roughly 2 km from the southeastern coastline of China, were used to screen for bioactive metabolites producing endophytic fungi. Endophytic fungal strains were isolated by using agar-based culture technique with three different selective media. A total 579 fungi were isolated from the leaf samples. The rDNA internal transcribed spacer (ITS) fragments of 208 (35.92%; 208 out of 579) fungal strains were amplified by polymerase chain reaction and sequenced. BLAST results suggested that they belong to three phyla, twenty-six families, and thity-three genera. The fungal strains inhabiting the mangrove plant were predominantly identified as Fusarium (40 strains, 19.4%), Didymella (19, 9.2%), and Allophoma (17, 8.3%). The antimicrobial activity of isolated fungi was performed against six indicator microorganisms by agar block methods. Among all the tested strains (243), 41.15% (100) of the strains showed antimicrobial activity against one or more of the indicator microorganisms. Fusarium (12 strains), Epicoccum (8), and Alternaria (6) were the three major genera with antimicrobial activity, accounting for 42% of the antibiotic-producing strains. six isolates, namely LS-04-05-sM-3, LS-04-01-sM-6-1, LS-05-01-sP-4, LS-03-04-sG-6, LS-04-02-eM-3 and LS-04-02-eM-5which exhibited strong or wide-spectrum antimicrobial activity were good candidates for further natural product isolation and characterization research. Our study demonstrated that the endophytic fungal diversity in mangrove plant Acanthus ilicifolius var. xiamenensis was high. Endophytic fungi from mangrove plant can be a source of natural antimicrobial agents; and these antibiotic-producing fungi may also play an important role in the ecological interaction between endophyes and their host.

Tese de mestrado, Ecologia Marinha, Universidade de Lisboa, Faculdade de Ciências, 2021
Mangroves are valued for their role in climate regulation, countering coastal erosion and providing raw materials. Mangroves have diverse fish communities, and the roots of mangrove trees provide shelter for fish species, especially juveniles. Little is known about Santomean mangroves, with 12 mangrove systems identified, from which four were included in this study. This thesis aims to comprehend how fish diversity varies between mangroves with different characteristics, using Santomean mangroves as case study. The environmental conditions found in the smaller systems were more homogeneous than those of the larger systems. Twenty-two species were sampled, with Malanza showing the highest richness and Praia das Conchas the lowest. The functional diversity results suggest that Malanza is more diverse and has a functionally richer community. This higher diversity is probably due to the heterogeneity of environmental conditions and their temporal stability. Angolares had low diversity, with an even but species poor community. Likely due to the environmental variability that only allows tolerant species to establish. The reduced size and depth of Diogo Nunes is probably stunting its diversity. Nevertheless, the fish community of Diogo Nunes is functionally more diverse than that of the larger Angolares system. Pelagic and marine species preferred larger and deeper mangroves, while benthic and estuarine species were predominant in Diogo Nunes. Species and functional diversity were positively correlated indicating complementarity between them and showing that functional diversity adds information about species-environment interactions. Functional and species evenness were not correlated showcasing the importance of the use of both metrics to acquire a more complete understanding of the communities. Taxonomic and functional diversity were negatively correlated indicating that species from different taxa may perform similar functions. From a management point of view this approach represents an advantage as it can identify which systems are more important for which groups, allowing the prioritizing of systems for conservation and management.

碩士
國立臺灣海洋大學
海洋生物研究所
105
Halophytophthora is an oomycetous genus and predominantly inhabits mangrove environment. Halophytophthora species mainly are saprobic but their spores can be food for other organisms in the mangrove food web, thus serving as secondary producers. A previous study has shown the production of polyunsaturated fatty acids in mycelia of Halophytophthora, especially eicosapentaenoic acid (EPA, 22:5 (n=3)) and arachidonic acid (ARA, 20:4 (n=6)). Fatty acids with double bonds in the fatty acid carbon chain are called polyunsaturated fatty acids (PUFAs). With the differences in the length of the carbon chain and the position of the double bonds, these fatty acids correspond to different PUFAs,e.g. docosahexaenoic acid (DHA, 22:6 (n=3)), EPA and ARA. These fatty acids have been reported to have beneficial health effects on human including loweringblood pressure, preventing cardiovascular disease and reducing inflammation. Traditionally, PUFAs can be consumed through marine fish but overfishing in recent years has prompted discovery of alternative sources of PUFAs. In this study, diversity of Halophytophthora in five different mangroves of Taiwan and their fatty acid profile were studied. A total of 14 isolates representing 5 different species were collected based on identification through morphology and sequence analysis of the nuclear 18S and internal transcribed spacers (ITS) rDNA, including H. avicenniae, H. batemanensis, H. exoprolifera, H. polymorphica and H. spinosa var. spinosa. Liquid fermentation of the 14 isolates of Halophytophthora in glucose/yeast extract/peptone broth was used to analyse the fatty acid composition of mycelia; ARA in total fatty acids ranged between 4.16%-29.94% while EPA ranged between 0%-14.16%. No EPA was detected in all isolates of H. spinosa var. spinosa, suggesting that they may lack specific enzymes to transform ARA to EPA. Phylogenetic analysis of the 18S and ITS rRNA gene showed that majority of the Halophytophthora sequences generated in this study and those from the GenBank constitute the Halophytophthora sensu stricto clade with the type species H. vesicula. However, H. spinosa var. spinosa is distantly related with the Halophytophthora sensu stricto clade and other genera in the Pythiaceae. This observation corroborates the result of the fatty acid analysis; Halophytophthora sensu stricto clade produced ARA and EPA while no EPA was produced by H. spinosa var. spinosa.