Morfodinâmica e a infauna na desembocadura do rio Itaguaré
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Data
2020-12-16
Autores
Oliveira, Bruno Júlio de
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Universidade Estadual Paulista (Unesp)
Resumo
A região costeira do estado de São Paulo abriga diferentes ambientes costeiros como praias arenosas, costões rochosos, sistemas estuarinos entre outros ambientes altamente dinâmicos. A fim de estudar e monitorar estes ambientes este trabalho teve como objetivo avaliar a relação entre a morfodinâmica da desembocadura do rio Itaguaré em Bertioga – SP e os invertebrados presentes na infauna dos bancos arenosos. Foram realizadas 22 campanhas entre abril de 2018 e julho de 2019. Para avaliar sua morfodinâmica foi realizado o monitoramento mensal com o uso de um drone para obtenção de fotografias aéreas, além da obtenção de dados sobre as ondas, ventos, marés e pluviosidade local. Para avaliar a biodiversidade da infauna foram feitos três perfis de 10 réplicas de 1 metro quadrado cada, onde realizamos a identificação dos organismos e contagem de suas galerias na superfície do substrato. Nos três perfis foram coletados sedimento para análise granulométrica e água para avaliar a salinidade, a fim de entender como estes parâmetros podem influenciar na distribuição e dinâmica das espécies. A partir das imagens obtidas foram gerados ortomosaicos georreferenciados da área de estudo. Integramos os resultados das análises granulométricas, densidade de galerias por metro quadrado, salinidade, e dos dados meteorológicos e oceanográficos, pudemos observar os processos que atuam na movimentação da desembocadura e na distribuição da biodiversidade. Foram encontrados os crustáceos Callichirus major e Leptuca spp., os poliquetas Diopatra cuprea e Scolelepis squamata e o molusco bivalve Tagelus plebeius. Pudemos observar um padrão sazonal de migração na desembocadura, onde houve permanência e deslocamento das barras para Oeste da praia nas estações próximas ao inverno e para Leste nas estações próximas ao Verão. Essa dinâmica foi o fator de maior influência na distribuição dos organismos encontrados, que são afetados pela movimentação da desembocadura em resposta as variações hidrodinâmicas local. Os padrões granulométricos mostraram ter grande influência na distribuição da biodiversidade. Em curta e média escala de tempo a desembocadura se apresentou altamente dinâmica em sua morfologia com grandes mudanças em seu processo meandrante, sendo possível o registro de processos de erosão e acressão sedimentar. Esses processos são responsáveis pelo aporte sedimentar na desembocadura que pode ser influenciada pelas taxas pluviométricas locais, aumentado a vazão do rio e o aporte de sedimentos fluviais. No perfil 1 e 3 notamos a maior presença dos poliquetas da família Spionidae associado a maior presença de lama, enquanto que no perfil 2 não tivemos grande ocorrência destes organismos por conta da maior quantidade de sedimentos arenosos. Os crustáceos do gênero Leptuca spp. foram encontrados em sua maioria nos pontos onde possuíam sedimentos arenosos, tendo baixa ocorrência em regiões de sedimentos arenolamosos. O entendimento das relações entre a biodiversidade e os processos que controlam sua distribuição no ambiente em que vivem é de grande importância para embasar políticas públicas de preservação e educação ambiental.
The coastal region of the state of São Paulo has different types of coastal environments such as sandy beaches, rocky shores, estuarine systems and other highly dynamic environments. In order to study and monitor these environments this study aimed to evaluate the relationship between the morphodynamics of the Itaguaré river outfall in Bertioga - SP and the invertebrates present in the sandy banks. We had 22 campaigns between April 2018 and July 2019. To assess its morphodynamics, a monthly monitoring was made using a drone to obtain aerial photographs, in addition to obtaining data on waves, winds, tides and local rainfall that helped to describe the local morphodynamic movements. To assess the invertebrates of the infauna, three profiles were made of 10 replicates of 1 square meter each, where we carried out the identification of the organisms and counting their galleries on the substrate surface. Sediment was also collected for granulometric analysis and water to assess salinity, in order to understand how these parameters can influence the distribution and dynamics of species. From the images obtained, processing was carried out and orthophotographys geo-referenced from the entire extension of the study area, together with the results of the granulometric analysis, density of galleries per square meter, salinity, and meteorological and oceanographic data, we were able to observe the processes that act in the movement of the outfall of the river and in the distribution of its biodiversity. Crustaceans Callichirus major and Leptuca spp., Polychaetes Diopatra cuprea and Scolelepis squamata and the bivalve mollusk Tagelus plebeius were found. We were able to observe a seasonal migration pattern at the outfall of the river, where there was permanence and displacement of the bars to the west of the beach in the winter seasons and to the east in the summer seasons. This dynamic was the most influential factor in the distribution of the organisms found, which are affected by the movement of the outfall in response to local hydrodynamic variations. The granulometric patterns have shown to have a great influence on the distribution of biodiversity. In a short and medium scale of time the region was highly dynamic in its morphology with major changes in its migratory process, making it possible to record processes of erosion and sedimentary accretion. These processes are responsible for the sedimentary input at the outfall, which can also be influenced by local rainfall rates, increasing the flow of the river and the inflow of river sediments. In profile 1 and 3 we noticed the greater presence of polychaetes of the Spionidae family associated with the greater presence of mud in these points, whereas in profile 2 we did not have a large occurrence of these organisms due to the greater amount of sandy sediments available in this region. Crustaceans of the genus Leptuca spp. were found mostly in the points where they had greater amount of sandy sediments, having low occurrence in regions of muddy sediments. Understanding the relationship between biodiversity and the processes that control its distribution in the environment they live is of great importance to support public policies for preservation and environmental education.
The coastal region of the state of São Paulo has different types of coastal environments such as sandy beaches, rocky shores, estuarine systems and other highly dynamic environments. In order to study and monitor these environments this study aimed to evaluate the relationship between the morphodynamics of the Itaguaré river outfall in Bertioga - SP and the invertebrates present in the sandy banks. We had 22 campaigns between April 2018 and July 2019. To assess its morphodynamics, a monthly monitoring was made using a drone to obtain aerial photographs, in addition to obtaining data on waves, winds, tides and local rainfall that helped to describe the local morphodynamic movements. To assess the invertebrates of the infauna, three profiles were made of 10 replicates of 1 square meter each, where we carried out the identification of the organisms and counting their galleries on the substrate surface. Sediment was also collected for granulometric analysis and water to assess salinity, in order to understand how these parameters can influence the distribution and dynamics of species. From the images obtained, processing was carried out and orthophotographys geo-referenced from the entire extension of the study area, together with the results of the granulometric analysis, density of galleries per square meter, salinity, and meteorological and oceanographic data, we were able to observe the processes that act in the movement of the outfall of the river and in the distribution of its biodiversity. Crustaceans Callichirus major and Leptuca spp., Polychaetes Diopatra cuprea and Scolelepis squamata and the bivalve mollusk Tagelus plebeius were found. We were able to observe a seasonal migration pattern at the outfall of the river, where there was permanence and displacement of the bars to the west of the beach in the winter seasons and to the east in the summer seasons. This dynamic was the most influential factor in the distribution of the organisms found, which are affected by the movement of the outfall in response to local hydrodynamic variations. The granulometric patterns have shown to have a great influence on the distribution of biodiversity. In a short and medium scale of time the region was highly dynamic in its morphology with major changes in its migratory process, making it possible to record processes of erosion and sedimentary accretion. These processes are responsible for the sedimentary input at the outfall, which can also be influenced by local rainfall rates, increasing the flow of the river and the inflow of river sediments. In profile 1 and 3 we noticed the greater presence of polychaetes of the Spionidae family associated with the greater presence of mud in these points, whereas in profile 2 we did not have a large occurrence of these organisms due to the greater amount of sandy sediments available in this region. Crustaceans of the genus Leptuca spp. were found mostly in the points where they had greater amount of sandy sediments, having low occurrence in regions of muddy sediments. Understanding the relationship between biodiversity and the processes that control its distribution in the environment they live is of great importance to support public policies for preservation and environmental education.
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Palavras-chave
Morfodinâmica, Monitoramento, Biodiversidade, Granulometria, Drone