Phytoplankton productivity and hydrology of the Maracajaú coastal ecosystem, Rio Grande do Norte State

Abstract

This paper refers to the first contribution about the phytoplankton community productivity related to the  hydrological parameters of the coastal ecosystem of Maracajaú-RN, which is located 67 km North of Natal City. This is an  important reef area named by the local inhabitants of “parrachos” a reef table type, which are located 6km from the coast  and have a key ecological role in maintaining a typical reef fauna and flora, increasing the local biodiversity. Plankton  and hydrological samples were collected at surface, during spring low tides, with a Van Dorn and Nansen bottles,  respectively. Sampling were carried out in the dry (February and March/00) and in rainy (May and June/00) seasons in  three fixed stations. The data showed that the studied ecosystem is free of organic pollution presenting high concentration  of dissolved oxygen. Salinity, water transparence and suspended material indicated continental influence, mainly during  the rainy season. The primary productivity varied between the two seasons being higher at the rainy season, varying the  ecosystem from oligotrophic at the reef area to eutrophic close to the coast.