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Portuguese estuarine systems and their essential ecological role for some fish species: trends and predictions in face of global changes
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Resumo(s)
Os ecossistemas de transição costeira como estuários e lagoas estão entre os ecossistemas aquáticos
mais produtivos do planeta, reconhecidos mundialmente como uma componente fundamental das zonas
costeiras em termos de relevância biológica e utilização antropogénica. Os estuários ao longo da costa
portuguesa diferem nas suas características geomorfológicas e hidrológicas. Estes sistemas
desempenham um papel crucial em termos de áreas de viveiro para espécies de peixes economicamente
importantes. Embora vários autores tenham observado uma elevada variabilidade específica nas
comunidades de peixes estuarinos ao longo da costa portuguesa, poucos estudos exploram os fatores
que a influenciam. A maioria dos estudos portugueses que envolvem estas comunidades concentram-se
num único estuário e, quando vários são analisados, focam-se em poucos fatores abióticos e bióticos na
avaliação da variabilidade específica das comunidades. O presente trabalho visa analisar a função
ecológica desempenhada pelos estuários portugueses para as comunidades de peixes, nomeadamente
em termos da variação da sua riqueza específica, utilizando uma base de dados históricos de 30 anos
proporcionada pela infraestrutura Rede Portuguesa de Monitorização Costeira (CoastNet). Para tal, foi
desenvolvido um modelo aditivo generalizado (GAM) de forma a analisar a variação da riqueza de
espécies de peixes em função das características temporais, espaciais e ambientais dos nove principais
sistemas estuarinos da costa portuguesa. Os resultados do presente trabalho demonstraram diferenças
significativas na riqueza de espécies de peixes no espaço (entre os nove estuários de estudo) e no tempo
(à escala anual e mensal), sendo estas diferenças influenciadas por fatores abióticos como a salinidade
e a temperatura. Adicionalmente, este modelo aditivo generalizado permitiu discutir cenários possíveis
de variações futuras dos fatores significativos causados pelos efeitos das alterações climáticas. Este tipo
de modelos poderá desempenhar um papel útil como instrumento preliminar para preparar planos de
conservação a longo prazo a incluir na legislação nacional.
Coastal transition ecosystems like estuaries and lagoons are amongst the most productive aquatic ecosystems on the planet, recognized worldwide as a fundamental component of coastal areas in terms of biological relevance and anthropogenic use. Estuaries along the Portuguese coast differ in their geomorphological and hydrological characteristics. These systems play a crucial role in terms of nursery areas for economically important fish species. Although several authors have observed high specific variability in estuarine fish communities along the Portuguese coast, few studies explore the factors that influence it. Most studies involving Portuguese fish communities focus on a single estuary and, when several are addressed, only a single factor is used to assess the specific variability of the communities. The present work aims to analyze the ecological role played by Portuguese estuaries for fish communities, namely in terms of their species richness, using a 30 year historical database provided by the Portuguese Coastal Monitoring Network Research Infrastructure (CoastNet RI). To this end, a generalized additive model (GAM) was developed to analyze the variation of species richness as a function of a set of temporal, spatial and environmental characteristics from the nine principal estuarine systems on the Portuguese coast. The results demonstrated significant differences in fish species richness in space (among the nine study estuaries) and time (at annual and monthly scales), and these differences were influenced by abiotic factors such as salinity and temperature. Possible scenarios of future variations caused by the effects of climate change on the significant factors were also discussed. The generalized additive models could be useful as a preliminary tool to prepare long-term conservation plans for national legislation.
Coastal transition ecosystems like estuaries and lagoons are amongst the most productive aquatic ecosystems on the planet, recognized worldwide as a fundamental component of coastal areas in terms of biological relevance and anthropogenic use. Estuaries along the Portuguese coast differ in their geomorphological and hydrological characteristics. These systems play a crucial role in terms of nursery areas for economically important fish species. Although several authors have observed high specific variability in estuarine fish communities along the Portuguese coast, few studies explore the factors that influence it. Most studies involving Portuguese fish communities focus on a single estuary and, when several are addressed, only a single factor is used to assess the specific variability of the communities. The present work aims to analyze the ecological role played by Portuguese estuaries for fish communities, namely in terms of their species richness, using a 30 year historical database provided by the Portuguese Coastal Monitoring Network Research Infrastructure (CoastNet RI). To this end, a generalized additive model (GAM) was developed to analyze the variation of species richness as a function of a set of temporal, spatial and environmental characteristics from the nine principal estuarine systems on the Portuguese coast. The results demonstrated significant differences in fish species richness in space (among the nine study estuaries) and time (at annual and monthly scales), and these differences were influenced by abiotic factors such as salinity and temperature. Possible scenarios of future variations caused by the effects of climate change on the significant factors were also discussed. The generalized additive models could be useful as a preliminary tool to prepare long-term conservation plans for national legislation.
Descrição
Tese de mestrado, Ecologia Marinha, Universidade de Lisboa, Faculdade de Ciências, 2022
Palavras-chave
Alterações climáticas infraestrutura de investigação CoastNet comunidades de peixes estuarinas dados históricos modelos aditivos generalizados Teses de mestrado - 2022