Bivalves filtradores e a regulação da eutrofização estuarina : biofiltração por Crassostrea rhizophorae da seção norte do sistema estuarino da Baía de Vitória-ES, Brasil

• Autor(a) principal: Leite, Thayana de Alencar
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/9151
• topic: Ostra; Séston; Regulação estuarina; Valoração econômica; Oyster; Estuarine regulation; Economic valuation; Ciências Ambientais; 55

The mangrove oyster (Crassostrea rhizophorae) is an important species for regulating the eutrophication of tropical estuarine ecosystems through the filtration capacity of the seashore to which it is exposed through the preferential ingestion of nano-phytoplanktonic particles. The biofiltration can be measured by the clearance rate (CR), that is, the volume of water that is filtered per unit of time, and can be applied from several methods, with emphasis on in situ biodegradation methods (CRbd) and of continuous flow in the laboratory (CRfc). The efficacy of the mangrove oyster filtration depends primarily on the availability of organic matter as well as biophysics to environmental conditions (e.g., salinity). In this context, the objective of the thesis was to analyze the ecosystem service for regulation of eutrophication (i.e., removal of organic seston) in the North Section of the Estuary System of the Bay of Vitoria - NSVBES. The NSVBES covers an area and volume of 10 km2 and 2.5x107 m 3 , respectively, whose average depth is less than 3 m. In the SNSEBV, the average residence time is 35 days, under a medium and semi-stratified euhalin condition, with total and organic seston concentrations, on average of 14.9 and 15.8 mg.L-1 , respectively. In this scenario, the CRbd of C. rhizophorae is 1.56 L.g-1 .h-1 . The CRbd by biomass in the NSVBES mangrove (3.77x105 kg.km-2 ) is 7.07x109 L.kg-1 .dia-1 , corresponding to a daily regulation of 28% of the estuarine volume. The economic value attributed to removal of organic seston, conversion of chlorophyll a to nitrogen, is US$ 298,327.22. The economic value of the ecosystem service of eutrophication regulation can act as monetary justification in environmental management for the conservation of estuarine natural resources. We emphasize the ecological importance of C. rhizophorae and needs to guarantee the effectiveness of the regulation service of estuarine eutrophication.