Concentrations and Fluxes of Nutrients and Suspended Organic Matter in a Tropical Estuarine System: The Tinharé-Boipeba Islands Archipelago (Baixo Sul Baiano, Brazil)

Abstract

Barboza, C.D.N.; Paes, E.T.; Jandre, K.A., and Marques, Jr., A.N., 2014. Concentrations and fluxes of nutrients and suspended organic matter in a tropical estuarine system: The Tinharé-Boipeba Islands Archipelago (Baixo Sul Baiano, Brazil).Variations in the concentrations and fluxes of nutrients and suspended organic matter were examined during tidal cycles in four sectors (Barra dos Carvalhos, Barra de Boipeba, Cairu, and Galeão) of the estuarine system of the Tinharé-Boipeba Islands Archipelago (ESTBIA) on the northeastern Brazilian coast. In this study, we obtained new data by sampling and also used data from the literature (for Galeão) to estimate the exchange of nutrients between the estuary and the adjacent sea and to evaluate the factors that control these fluxes. It was observed that the factors that most influenced the nutrient fluxes in the estuarine system were the variations in the tidal prism and in the fluviometric regime. Moreover, the highest concentrations of dissolved inorganic nutrients occurred during the neap tide cycle, whereas the highest concentrations of particulates were found in the spring cycle. Organic carbon was transported in greater amounts in the dissolved form than in the particulate form, whereas nitrogen occurred predominantly in the organic form. The C : N and C : P ratios of the particulate organic material were typically high, showing a certain degree of seasonality related to the level of flooding of the mangroves. The nutrient fluxes transported in each sector showed the following tendency: Galeão ≥ Cairu >> Barra dos Carvalhos >> Barra de Boipeba. The net budgets for water and nutrients obtained for Galeão always reflected export from the estuary. In the other regions, particulate organic carbon, NO , NO , and NH were also exported from the estuary, whereas the remaining nutrients were exported during the neap tide cycle and imported during the spring cycle.