Castal areas are subject to a wide variety of anthropogenic impacts, among the most common are the impact of domestic sewage and uses for aquiculture. These human actions affect the estuarine environment in different ways, influencing the benthic community and consequently its metabolism patterns. There is a general scarcity of studies targeting nutrient fluxes and benthic metabolism measurements in different contrasting human impacted area, in particular in low latitude coastal zones. In this study, the impact on nutrient fluxes and benthic metabolism was observed in an oyster farming at Cananéia-Iguape Estuarine-Lagoon Complex (pristine estuary) and in a sewage discharge area in São Vicente-Santos Estuarine Complex (impacted estuary), in southeastern Brazilian coast. Intact sediment corers were sampled on both estuaries in two seasons (summer and winter) and processed in laboratory. Laboratorial dark incubations were performed to measured flux of dissolved gases and inorganic nutrients. A second incubation was performed with stable isotope paring techniques, to observe the effects on the benthic denitrification rates. Results showed a higher metabolism in sediment of São Vicente in both seasons. These results coincide with a bigger macrofauna and higher organic matter and chlorophyll content in this location. In general, São Vicente station showed the highest values of organic matter, higher regeneration from sediments of ammonium and nitrate and dinitrogen consumption, and higher rates of denitrification. In summer, nutrient fluxes, sediment metabolism, and denitrification rates increased in both sites.

Primary Presenter: Paula Moraes, Oceanographyc Institute, Universidade de São Paulo (pamoraes@usp.br)

Authors:

Paula Moraes, Oceanographyc Institute, Universidade de São Paulo  (pamoraes@usp.br)

Bruno Sutti, Oceanographyc Institute, Universidade de São Paulo  (brunoosutti@gmail.com)

Vitor Chiozzini, Oceanographyc Institute, Universidade de São Paulo  (vitor.chio@gmail.com)

Marco Bartoli, University of Parma  (marco.bartoli@unipr.it)

Elisabete Braga, Oceanographyc Institute, Universidade de São Paulo  (edsbraga@usp.br)