Produtividade fitoplactÃnica e hidrologia no ecossistema recifal de Porto de Galinhas (Pernambuco- Brasil)




The Porto de Galinhas beach, located in the south coast of Pernambuco, Brazil, about 50 kilometers from Recife, has coral reef formations that form natural pools of extreme beauty, and thus, actually is undergoing an intense tourist activity, as one of the most visited beaches of Northeastern Brazil. The phytoplankton productivity and biomass and some hydrologic parameters were studied to assess the environmental quality of the area. Water samples were collected with Kitahara bottle in the water sub-surface, during three months of the dry and rainy seasons, in three fixed sites, during the diurnal low and high tides of the same day. The diurnal variation of phytoplankton biomass and hydrological parameters was studied in a fixed site, in dry and rainy seasons, in ebb, low, flood and high tides. Temperature, salinity, water transparency, dissolved oxygen and its saturation level presented higher values during the dry season, while the suspended material, nitrite, productivity, assimilation number and pH presented higher values during the rainy season. In the Principal Components Analysis the rain presented direct correlation with the suspended material, nitrite and productivity and inverse correlation with dissolved oxygen, oxygen saturation level, temperature and water transparency. The reef ecosystem is free of organic pollution ranging from oligotrophic (dry season) to eutrophic (rainy season) and, in the rainy season, the plume of MaracaÃpe river can change the conditions in this system. The fraction smaller than 20 μm (pico and nanophytoplankton) was the largest contributor in biomass and productivity. The environmental parameters varied more in relation to seasonality than different times of day and tide stages. The presence of walls to contain the sea affect the dynamic environment. Although the reef ecosystem have a strong impact due to the intense tourist spot, this was not perceived in the pelagic environment.


oceanografia fitoplÃncton phytoplankton ecossistema recifal hydrology produtividade hidrologia reef ecosystem productivity

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