Mangroves are tropical and subtropical coastal ecosystems located in estuarine zones, important for the maintenance of biogeochemical cicles, marine fauna reproduction and the economy. However, these environments are under constant pressure, including contamination by oil and its derivatives threatens these environments. The use of microbial biosurfactants for environmental decontamination has been considered an eco-friendly alternative. The aim of this research was to collect and characterize biosurfactant-producing bacterial strains that emulsify oil products in Rio Cocà Mangrove, Fortaleza, CearÃ. One collection in rainy season and other one in dry season were made in two points, one of them in Cocà Ecological Park and another one in the river mouth. A total, 4 soil samples, 4 water samples and 4 Laguncularia racemosa seedlings were collected. The samples were homogenized and a fraction was added in Erlemeyers containing Bushnell-Haas broth added with kerosene and gasoline and incubated at 30 C for periods of 48 and 72 h. Inocula were made on the surface of TSA agar medium, incubated at 35ÂC for 48 h and then colonies were selected and isolated. The strains were characterized and verified the purity of cultures by Gram staining technique. Biosurfactant production capacity was assessed by drop collapse test and the detected emulsion was after assessed by volume and stability emulsification tests and emulsifier activity test. A total, 58 strains were isolated, 50 are Gram-negative and 8 are Gram-positive, separated according the source: 21 from water, 21 from sediment and 16 from the rhizosphere of seedlings. A total of 55 strains (95%) had positive results in the drop collapse test. All 10 strains with emulsification volume above 50% in 24 hours also exhibited stability above 50% up to 168 hours. Five strains showed emulsifying activity above 2,00 UAE, while 29 strains showed activity between 1,00 and 2,00 UAE. We concluded that it is possible to isolate biosurfactant-producing bacteria from Rio Cocà mangrove and that the most efficient strains in the tests were isolated from the point located in the Cocà Ecological Park. / Manguezais sÃo ecossistemas costeiros tropicais e subtropicais, localizados em zonas estuarinas, importantes para a manutenÃÃo dos ciclos biogeoquÃmicos, reproduÃÃo de espÃcies marinhas e para a economia. Apesar disso, sofrem constantemente pressÃo ambiental, incluindo a contaminaÃÃo por petrÃleo e derivados. O uso de biossurfactantes microbianos para descontaminaÃÃo ambiental tem sido considerado uma alternativa mais sustentÃvel. O objetivo da presente pesquisa foi coletar e caracterizar cepas bacterianas produtoras de biossurfactantes que emulsifiquem derivados de petrÃleo no Mangue do Rio CocÃ, Fortaleza, CearÃ. Foi realizada uma coleta no perÃodo chuvoso e outra no perÃodo seco em dois pontos no Rio CocÃ, sendo um deles no Parque EcolÃgico do Cocà e outro na foz do rio. No total, foram coletadas 4 amostras de solo, 4 de Ãgua e 4 de plÃntulas de Laguncularia racemosa. As amostras coletadas foram homogeneizadas e uma fraÃÃo foi acrescentada em Erlenmeyers contendo caldo Bushnell-Haas adicionado de querosene e gasolina e incubados em estufa a 30ÂC por perÃodos de 48 e 72 h. A partir do crescimento, visualizado pela turvaÃÃo do meio, foram feitos inÃculos sobre a superfÃcie do meio Ãgar TSA, que foram incubadas em estufa a 35ÂC por 48 h e posteriormente as colÃnias crescidas foram selecionadas e isoladas. As cepas foram caracterizadas e a pureza das culturas foi verificada pela tÃcnica de coloraÃÃo de Gram. A capacidade de produÃÃo dos biossurfactantes foi detectada pelo teste do colapso da gota e o emulsificante detectado foi posteriormente avaliado pelos testes de volume e estabilidade de emulsificaÃÃo e atividade emulsificante. Foram isoladas 58 cepas, sendo 50 delas Gram-negativas e 8 Gram-positivas, assim separadas de acordo com a origem: 21 de Ãgua, 21 de sedimento e 16 da rizosfera das plÃntulas. No total, 55 cepas (95%) tiveram resultados positivos no teste do colapso da gota. Todas as 10 cepas que apresentaram volume de emulsificaÃÃo acima de 50% em 24 horas tambÃm apresentaram estabilidade acima de 50% atà 168 horas. Cinco cepas apresentaram atividade emulsificante acima de 2,00 UAE, enquanto 29 cepas mostraram atividade entre 1,00 e 2,00 UAE. Conclui-se que à possÃvel isolar bactÃrias produtoras de biossurfactantes do Mangue do Rio Cocà e que as cepas mais eficientes nos testes realizados foram isoladas do ponto localizado no Parque EcolÃgico do CocÃ.

A Baixada Santista encontra-se na região central do litoral de São Paulo (23o55\'S). É um típico ambiente costeiro tropical dominado por extensos manguezais. Entretanto, o sistema vem sofrendo intenso processo de alteração ambiental devido a atividades industriais e portuárias, além da ausência de planejamento urbano. O presente estudo foi realizado em bosques de mangue na Ilha Barnabé, onde ocorreu derramamento e combustão de produto químico (diciclopentadieno - DCPD), em 1998. A fim de avaliar o grau de perturbação e os processos regenerativos dos bosques de mangue foram caracterizadas a estrutural vegetal, área foliar, microtopografia e produção de serapilheira, durante 25 meses, entre fevereiro de 2002 e a fevereiro de 2004. As características estruturais mostraram mortalidade e formação de clareiras seguidas de regeneração. Também foram observadas deformidades foliares e erosão como conseqüência do evento. A produção de serapilheira sugere certa desordem funcional no sistema. A metodologia utilizada mostrou-se adequada como ferramenta para avaliação de impactos em bosques de mangue. Sugere-se monitoramento de longo prazo nas áreas de manguezal impactadas para melhor compreensão dos efeitos de tensores naturais e/ou induzidos pelo homem. / The Baixada Santista and Santos Estuary are located in the central portion of the São Paulo State coastline (23º55\'S). It is a typical tropical coastal environment dominated by extensive mangroves areas despite the intensive harbor and heavy industrial activities, and their location within a continually evolving human landscape. The present study was developed in a mangrove area at Barnabé Island (Santos Estuary), a site impacted in 1998 by a DCPD (dicyclopentadiene) spill that was followed by a fire. In order to assess residual impacts, and to describe natural restoration processes, leaf area, microtopography, and litter fall during the 25 months period from February 2002 to February 2004 was monitored. Structural changes included gap formation due to mangrove tree mortality and partial regeneration. Leaf deformities were observed as well as accelerated coastal erosion due to the loss of the mangrove fringe. Litter fall production suggests a systemic level functional impairment. The methodology used appears adequate to describe and assess the level of impact and recovery pattern of a mangrove stand affected by a chemical spill. It is suggested that more extensive (long-term) monitoring studies on impacted mangroves must be developed as effective tools helping to understand the response of systems exposed to natural or human-induced stressors.

Made available in DSpace on 2016-08-19T17:47:13Z (GMT). No. of bitstreams: 1 DENILSON DA SILVA BEZERRA.pdf: 6804367 bytes, checksum: 52108d283a1644252b9077555f5302ea (MD5) Previous issue date: 2008-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The ecosystem of mangroves possesses great relevance for the coastal area, fact that puts it as an intangible area for the juridical system of Brazil. However this, doesn't take into account the socioeconomic and real estate pressures imposed for this environment in the urban centers, appearing this way, paradoxical situations for the ecosystem, as well as, also, to the quality of human life. There for, the present study aims at to propose the insert of mangrove in municipal politics of use and occupation of the soil. For that, the scenery of the basin of the river Anil was used (São Luís-MA) in an interval of time from 1975 to 2001 with the aid of the geoprocessament tool. As result was obtained vectorial files of the alterations caused by the progress of the urban perimeter towards the environment object of the research (reduction of this around 35, 44%), as well as, estimate of this process in the neighborhoods of the Liberdade (R$ 20.560.400) and Jaracati (R$ 10.006.233). Being concluded this way that vectors socials, economicals and immobilities address the process of use of the environment focus of the present researches in the analyzed area. / O ecossistema manguezal possui grande relevância para a zona costeira, fato que o coloca como uma área intangível pelo sistema jurídico do Brasil. Porém este, não leva em consideração as pressões socioeconômicas e imobiliárias impostas a tal ambiente nos centros urbanos, surgindo desta forma, situações paradoxais para o ecossistema, assim como, também, para com a qualidade de vida humana. Sendo assim, o presente estudo objetiva propor a inserção do manguezal em políticas municipais de uso e ocupação do solo. Para isso, foi utilizado o cenário da bacia do rio Anil (São Luís-MA) em um intervalo de tempo de 1975 a 2001 com o auxílio da ferramenta de geoprocessamento. Como resultado obteve-se arquivos vetoriais das alterações ocasionadas pelo avanço do perímetro urbano em direção ao ambiente objeto da pesquisa (redução deste em torno de 35,44 %), assim como, estimativa de custo deste processo nos bairros da Liberdade (R$ 20.560.400) e Jaracati (R$ 10.006.233). Concluindo-se desta forma que vetores sócias, econômicos e mobiliários direcionam o processo de uso do ambiente foco da presente pesquisa na área analisada.

A Baixada Santista encontra-se na região central do litoral de São Paulo (23o55\'S). É um típico ambiente costeiro tropical dominado por extensos manguezais. Entretanto, o sistema vem sofrendo intenso processo de alteração ambiental devido a atividades industriais e portuárias, além da ausência de planejamento urbano. O presente estudo foi realizado em bosques de mangue na Ilha Barnabé, onde ocorreu derramamento e combustão de produto químico (diciclopentadieno - DCPD), em 1998. A fim de avaliar o grau de perturbação e os processos regenerativos dos bosques de mangue foram caracterizadas a estrutural vegetal, área foliar, microtopografia e produção de serapilheira, durante 25 meses, entre fevereiro de 2002 e a fevereiro de 2004. As características estruturais mostraram mortalidade e formação de clareiras seguidas de regeneração. Também foram observadas deformidades foliares e erosão como conseqüência do evento. A produção de serapilheira sugere certa desordem funcional no sistema. A metodologia utilizada mostrou-se adequada como ferramenta para avaliação de impactos em bosques de mangue. Sugere-se monitoramento de longo prazo nas áreas de manguezal impactadas para melhor compreensão dos efeitos de tensores naturais e/ou induzidos pelo homem. / The Baixada Santista and Santos Estuary are located in the central portion of the São Paulo State coastline (23º55\'S). It is a typical tropical coastal environment dominated by extensive mangroves areas despite the intensive harbor and heavy industrial activities, and their location within a continually evolving human landscape. The present study was developed in a mangrove area at Barnabé Island (Santos Estuary), a site impacted in 1998 by a DCPD (dicyclopentadiene) spill that was followed by a fire. In order to assess residual impacts, and to describe natural restoration processes, leaf area, microtopography, and litter fall during the 25 months period from February 2002 to February 2004 was monitored. Structural changes included gap formation due to mangrove tree mortality and partial regeneration. Leaf deformities were observed as well as accelerated coastal erosion due to the loss of the mangrove fringe. Litter fall production suggests a systemic level functional impairment. The methodology used appears adequate to describe and assess the level of impact and recovery pattern of a mangrove stand affected by a chemical spill. It is suggested that more extensive (long-term) monitoring studies on impacted mangroves must be developed as effective tools helping to understand the response of systems exposed to natural or human-induced stressors.

Understanding women’s experiences of mangrove forest conservation in the Global South is important because mangrove forests are a crucial defense against climate change, and are also increasingly the targets of global climate change policies. The intervention of postcolonial feminist theory combined with feminist political ecology has the potential to bring forward women’s seldom-heard experiences of climate change in these valuable ecosystems. This work supports previous feminist political ecology scholarship focused on understanding women’s complicated relationships to the environment and the gendered effects of climate change policies, while challenging dominant conservation discourse around women as a monolithic group. This thesis focuses on women living in Madagascar’s largest mangrove, particularly under current mangrove reforestation efforts and emerging blue carbon climate change policies. This project explores how the women in this mangrove forest are situated along axes of power differently, the implications of social divisions for conservation, and the ways in which current mangrove conservation projects reproduce power relations in the mangrove by failing to recognize difference.

This mini-dissertation contains the results of research to establish a[1 economic value for the mangroves of the Mngazana Estuary in the Eastern Cape. The research is presented in two parts. Component A comprises the literature review and also describes the scope and context for the study, its purpose and the proposed methodology. Component B presents the results of the research in the format of an article to be submitted for publication to the African Journal of Marine Science. Estuaries and mangroves are among the most threatened habitats in South Africa, with the third largest mangrove forest in South Africa at the Mngazana Estuary on the Wild Coast of the Eastern Cape gradually reducing in size. A lack of appreciation of their value has resulted in policies and decisions that promoted the conversion of estuary and mangrove ecosystems to alternative uses, and caused a large-scale loss of mangroves throughout the world. Apart from their key ecological role, the Mngazana Estuary mangroves provide important benefits to the 645 households in three villages that utilise the resources and the sustainable use and management of the mangroves is essential. Economic valuation ascribes values to traded and untraded environmental resources and is a tool that supports policy formulation and decision-making on sustainable management of resources like mangroves. The theory of total economic value provides the conceptual framework for estimating the economic value, but constraints limited this study to estimating the socio-economically significant benefits the mangroves bestow on the communities around the Mngazana Estuary. Using information collected in a household survey and focus group discussions, market-price methods were used to estimate the value of mangroves harvested for building materials and the subsistence consumption of fish by the communities. Values were estimated for mangrove-dependent canoe trails and honey production operations, while a recreational use value was estimated on the basis of travel costs and expenses incurred by visitors to the holiday cottages adjacent to the estuary. The results were incorporated in 20-year valuation models with the net annual benefits then discounted to present value terms. Sensitivity analysis was performed to estimate lower-bound, upper-bound and most-likely values for the benefits. The minimum economic value of the mangroves was estimated to be between R1.1 and R13.6 million, with a most-likely value at a real 5% discount rate of R7.4 million. This study has shown that policies for managing environmental resources must be ecologically, socially and economically sound. This requires an integrated approach to address the socio-economic needs of local communities while safe-guarding environmental resources. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Coastal wetlands dominated by mangroves provide important ecological services to the coastal zone, many of which are associated with tidal inundation . In this study I investigated whether all coastal wetlands provide similar ecosystem services, or whether these varied depending on their geomorphological setting and the eutrophication level of the floodwater. Sampling was conducted over two years with significantly different levels of rainfall over six estuaries in Southeast Queensland, Australia. Sediment, nutrient and carbon exchange were investigated in tidal and riverine estuaries dominated by mangrove forests. The estuaries selected also comprised a gradient from low mesotrophic to low eutrophic. Spatial variation within the coastal wetlands was also investigated, comparing nutrient exchange in the low and high intertidal cyanobacteria mat . To assess sediment exchange, I measured retention of total suspended solids and sedimentation rates. Additionally, in order to assess the origin of sediment deposited in mangroves, glomalin, a novel terrestrial soil carbon (C) tracer, was used. Nutrient and C exchange were quantified by comparison of concentrations of soluble reactive phosphorus (SRP), nitrogen oxides (NOx--N), ammonium (NH4+) total organic carbon (TOC) and dissolved organic C (DOC) in water entering and leaving the mangroves during complete tidal cycles (3 tidal cycles in 6 estuaries for 2 years). Finally, the biogeochemical function of the cyanobacteria mat was measured through experiments investigating nitrogen fixation (N) and nutrient exchange in the extensive mats in the Exmouth Gulf, Western Australia. My results show that the seaward fringe mangrove retains the majority of sediment entering the wetland during a tidal cycle accounting for 52.5 ± 12.5 % of the total sedimentation (fringe mangrove + scrub mangrove + saltmarsh/ cyanobacteria mat). Geomorphological setting had a stronger influence on spatial patterns of deposition than on sedimentation rates. Riverine mangroves had more homogeneous distribution of sediments across the intertidal zone than tidal mangroves, where most sedimentation occurred in the seaward fringe mangrove zone. The presence of glomalin in sediments, and thus the relative importance of terrigenous sediment, was strongly influenced by geomorphological setting. Glomalin was primarily delivered to riverine mangroves and deposited within the scrub mangrove zone, while tidal mangroves received less glomalin during tidal inundation and most of it was deposited within the fringe mangrove zone. Overall, NOx--N concentrations decreased in the floodwater after flooding the coastal wetland, suggesting that these ecosystems act as sinks of dissolved NOx--N during tidal inundation. In average, NOx--N concentrations in the floodwater decreased 28 %. Additionally, during periods of high rainfall the decrease in nutrient concentrations was more pronounced, and not only NOx--N but also SRP and NH4+ concentrations decreased to up to 51 % and 83 %, respectively. My results suggest that rainfall enhances nutrient removal by coastal wetlands in the region. Geomorphological setting also affected nutrient removal. Riverine mangroves received stronger nutrient pulses, which resulted in strongest rates of nutrient removal during tidal inundation. Nutrient removal was closely related to the nutrient concentration of the floodwater: high nutrient removal occurred when floodwater was rich in nutrients. The C entering the wetland in the floodwater was mainly composed of DOC and its exchange did not vary among sites with differing geomorphological setting. However, DOC exchange was strongly affected by the water quality of floodwater inundating the coastal wetland. DOC concentrations were higher in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC import. Contrary, DOC concentrations were lower in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC export. The high intertidal cyanobacteria mat was important in regulating N fluxes in coastal wetlands. In the arid Exmouth Gulf, where cyanobacteria mats are abundant, nitrogen fixation rates were 4.9 ± 3.2 nmol cm-1 h-1. Cyanobacteria mats also removed N from the floodwater in the form of NOx--N (0.47 ± 0.45 g m-2 h-1) and NH4+ (0.31 ± 0.02 g m-2 h-1). N fixation and nutrient removal from the floodwater was highly variable spatially and temporally. N fixation rates were highest during the day in the mat situated at low tidal elevations. Overall, I found that the material exchange in coastal wetlands is variable within the coastal zone as a result of natural factors, such as geomorphology, vegetation composition and rainfall. But material exchange in wetlands is also affected by anthropogenic factors, particularly eutrophication. From all these factors, eutrophication of the floodwater appears to be the most critical, shifting the mangrove function from a DOC source to a nutrient and DOC sink. Approximate thresholds of nutrient and C concentrations in the floodwater that are likely to trigger shifts in ecosystem function in coastal wetlands in Southeast Queensland, and thus in the ecosystem services they provide, are 0.02 mg L-1 of SRP, 0.04 mg L-1 of NH4+ and 7.5 mg L-1 of DOC.

Coastal wetlands dominated by mangroves provide important ecological services to the coastal zone, many of which are associated with tidal inundation . In this study I investigated whether all coastal wetlands provide similar ecosystem services, or whether these varied depending on their geomorphological setting and the eutrophication level of the floodwater. Sampling was conducted over two years with significantly different levels of rainfall over six estuaries in Southeast Queensland, Australia. Sediment, nutrient and carbon exchange were investigated in tidal and riverine estuaries dominated by mangrove forests. The estuaries selected also comprised a gradient from low mesotrophic to low eutrophic. Spatial variation within the coastal wetlands was also investigated, comparing nutrient exchange in the low and high intertidal cyanobacteria mat . To assess sediment exchange, I measured retention of total suspended solids and sedimentation rates. Additionally, in order to assess the origin of sediment deposited in mangroves, glomalin, a novel terrestrial soil carbon (C) tracer, was used. Nutrient and C exchange were quantified by comparison of concentrations of soluble reactive phosphorus (SRP), nitrogen oxides (NOx--N), ammonium (NH4+) total organic carbon (TOC) and dissolved organic C (DOC) in water entering and leaving the mangroves during complete tidal cycles (3 tidal cycles in 6 estuaries for 2 years). Finally, the biogeochemical function of the cyanobacteria mat was measured through experiments investigating nitrogen fixation (N) and nutrient exchange in the extensive mats in the Exmouth Gulf, Western Australia. My results show that the seaward fringe mangrove retains the majority of sediment entering the wetland during a tidal cycle accounting for 52.5 ± 12.5 % of the total sedimentation (fringe mangrove + scrub mangrove + saltmarsh/ cyanobacteria mat). Geomorphological setting had a stronger influence on spatial patterns of deposition than on sedimentation rates. Riverine mangroves had more homogeneous distribution of sediments across the intertidal zone than tidal mangroves, where most sedimentation occurred in the seaward fringe mangrove zone. The presence of glomalin in sediments, and thus the relative importance of terrigenous sediment, was strongly influenced by geomorphological setting. Glomalin was primarily delivered to riverine mangroves and deposited within the scrub mangrove zone, while tidal mangroves received less glomalin during tidal inundation and most of it was deposited within the fringe mangrove zone. Overall, NOx--N concentrations decreased in the floodwater after flooding the coastal wetland, suggesting that these ecosystems act as sinks of dissolved NOx--N during tidal inundation. In average, NOx--N concentrations in the floodwater decreased 28 %. Additionally, during periods of high rainfall the decrease in nutrient concentrations was more pronounced, and not only NOx--N but also SRP and NH4+ concentrations decreased to up to 51 % and 83 %, respectively. My results suggest that rainfall enhances nutrient removal by coastal wetlands in the region. Geomorphological setting also affected nutrient removal. Riverine mangroves received stronger nutrient pulses, which resulted in strongest rates of nutrient removal during tidal inundation. Nutrient removal was closely related to the nutrient concentration of the floodwater: high nutrient removal occurred when floodwater was rich in nutrients. The C entering the wetland in the floodwater was mainly composed of DOC and its exchange did not vary among sites with differing geomorphological setting. However, DOC exchange was strongly affected by the water quality of floodwater inundating the coastal wetland. DOC concentrations were higher in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC import. Contrary, DOC concentrations were lower in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC export. The high intertidal cyanobacteria mat was important in regulating N fluxes in coastal wetlands. In the arid Exmouth Gulf, where cyanobacteria mats are abundant, nitrogen fixation rates were 4.9 ± 3.2 nmol cm-1 h-1. Cyanobacteria mats also removed N from the floodwater in the form of NOx--N (0.47 ± 0.45 g m-2 h-1) and NH4+ (0.31 ± 0.02 g m-2 h-1). N fixation and nutrient removal from the floodwater was highly variable spatially and temporally. N fixation rates were highest during the day in the mat situated at low tidal elevations. Overall, I found that the material exchange in coastal wetlands is variable within the coastal zone as a result of natural factors, such as geomorphology, vegetation composition and rainfall. But material exchange in wetlands is also affected by anthropogenic factors, particularly eutrophication. From all these factors, eutrophication of the floodwater appears to be the most critical, shifting the mangrove function from a DOC source to a nutrient and DOC sink. Approximate thresholds of nutrient and C concentrations in the floodwater that are likely to trigger shifts in ecosystem function in coastal wetlands in Southeast Queensland, and thus in the ecosystem services they provide, are 0.02 mg L-1 of SRP, 0.04 mg L-1 of NH4+ and 7.5 mg L-1 of DOC.

Coastal wetlands dominated by mangroves provide important ecological services to the coastal zone, many of which are associated with tidal inundation . In this study I investigated whether all coastal wetlands provide similar ecosystem services, or whether these varied depending on their geomorphological setting and the eutrophication level of the floodwater. Sampling was conducted over two years with significantly different levels of rainfall over six estuaries in Southeast Queensland, Australia. Sediment, nutrient and carbon exchange were investigated in tidal and riverine estuaries dominated by mangrove forests. The estuaries selected also comprised a gradient from low mesotrophic to low eutrophic. Spatial variation within the coastal wetlands was also investigated, comparing nutrient exchange in the low and high intertidal cyanobacteria mat . To assess sediment exchange, I measured retention of total suspended solids and sedimentation rates. Additionally, in order to assess the origin of sediment deposited in mangroves, glomalin, a novel terrestrial soil carbon (C) tracer, was used. Nutrient and C exchange were quantified by comparison of concentrations of soluble reactive phosphorus (SRP), nitrogen oxides (NOx--N), ammonium (NH4+) total organic carbon (TOC) and dissolved organic C (DOC) in water entering and leaving the mangroves during complete tidal cycles (3 tidal cycles in 6 estuaries for 2 years). Finally, the biogeochemical function of the cyanobacteria mat was measured through experiments investigating nitrogen fixation (N) and nutrient exchange in the extensive mats in the Exmouth Gulf, Western Australia. My results show that the seaward fringe mangrove retains the majority of sediment entering the wetland during a tidal cycle accounting for 52.5 ± 12.5 % of the total sedimentation (fringe mangrove + scrub mangrove + saltmarsh/ cyanobacteria mat). Geomorphological setting had a stronger influence on spatial patterns of deposition than on sedimentation rates. Riverine mangroves had more homogeneous distribution of sediments across the intertidal zone than tidal mangroves, where most sedimentation occurred in the seaward fringe mangrove zone. The presence of glomalin in sediments, and thus the relative importance of terrigenous sediment, was strongly influenced by geomorphological setting. Glomalin was primarily delivered to riverine mangroves and deposited within the scrub mangrove zone, while tidal mangroves received less glomalin during tidal inundation and most of it was deposited within the fringe mangrove zone. Overall, NOx--N concentrations decreased in the floodwater after flooding the coastal wetland, suggesting that these ecosystems act as sinks of dissolved NOx--N during tidal inundation. In average, NOx--N concentrations in the floodwater decreased 28 %. Additionally, during periods of high rainfall the decrease in nutrient concentrations was more pronounced, and not only NOx--N but also SRP and NH4+ concentrations decreased to up to 51 % and 83 %, respectively. My results suggest that rainfall enhances nutrient removal by coastal wetlands in the region. Geomorphological setting also affected nutrient removal. Riverine mangroves received stronger nutrient pulses, which resulted in strongest rates of nutrient removal during tidal inundation. Nutrient removal was closely related to the nutrient concentration of the floodwater: high nutrient removal occurred when floodwater was rich in nutrients. The C entering the wetland in the floodwater was mainly composed of DOC and its exchange did not vary among sites with differing geomorphological setting. However, DOC exchange was strongly affected by the water quality of floodwater inundating the coastal wetland. DOC concentrations were higher in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC import. Contrary, DOC concentrations were lower in the flood compared to the ebb tide in sites flooded by water high in C, NH4+ and SRP, suggesting DOC export. The high intertidal cyanobacteria mat was important in regulating N fluxes in coastal wetlands. In the arid Exmouth Gulf, where cyanobacteria mats are abundant, nitrogen fixation rates were 4.9 ± 3.2 nmol cm-1 h-1. Cyanobacteria mats also removed N from the floodwater in the form of NOx--N (0.47 ± 0.45 g m-2 h-1) and NH4+ (0.31 ± 0.02 g m-2 h-1). N fixation and nutrient removal from the floodwater was highly variable spatially and temporally. N fixation rates were highest during the day in the mat situated at low tidal elevations. Overall, I found that the material exchange in coastal wetlands is variable within the coastal zone as a result of natural factors, such as geomorphology, vegetation composition and rainfall. But material exchange in wetlands is also affected by anthropogenic factors, particularly eutrophication. From all these factors, eutrophication of the floodwater appears to be the most critical, shifting the mangrove function from a DOC source to a nutrient and DOC sink. Approximate thresholds of nutrient and C concentrations in the floodwater that are likely to trigger shifts in ecosystem function in coastal wetlands in Southeast Queensland, and thus in the ecosystem services they provide, are 0.02 mg L-1 of SRP, 0.04 mg L-1 of NH4+ and 7.5 mg L-1 of DOC.

Os manguezais são ecossistemas complexos, que estão sujeitos a processos que ocorrem ao longo de diferentes escalas temporais e espaciais. Essa complexidade reforça a importância de se empregar abordagens que possam alcançar essas escalas. As florestas de mangue, entre outras funções, funcionam como sequestradoras e fixadoras de carbono, sendo importantes para o equilíbrio do balanço global de gás carbônico. Estudos relacionados a diversos biomas mostram que há diferença de teor de carbono para espécies diferentes. Diversas estimativas de estoque e sequestro de carbono em florestas de mangue adotam o valor de 45% para o teor de carbono nas espécies de mangue. O presente estudo realizado em Guaratiba, Rio de Janeiro, coletou ramos, folhas, troncos, partes reprodutivas e raízes subterrâneas das espécies ali encontradas: Avicennia schaueriana, Laguncularia racemosa e Rhizophora mangle, essa última teve ainda a coleta de rizóforos, para determinação do teor de carbono nos diferentes compartimentos das diferentes espécies. As amostragens foram realizadas nos diferentes tipos fisiográficos (franja, bacia e transição). O material seco foi triturado e determinado por autoanalisador CHN. Os resultados foram testados estatisticamente, através de análise de variância (ANOVA) e teste de Tukey para identificação de diferenças entre os tipos fisiográficos, espécies e compartimentos (para p<0,05). Foi obtido um valor de teor de carbono orgânico para as partes lenhosas (44,1%) para todas as espécies; um valor para partes verdes de A. schaueriana e L. racemosa de 42,6% e R. mangle de 44,9%; e um valor para raiz de A. schaueriana e L. racemosa de 42,6% e R. mangle de 40,0%. Não foi detectada influência dos tipos fisiográficos sobre o teor de carbono na floresta de mangue estudada. Os resultados aqui obtidos demonstram ainda que deve-se ter cautela na utilização de um valor único e global para o teor de carbono em espécies de mangue.