Nutrient composition of macroalgae and macrophytes of the Açu lagoon, Rio de Janeiro State, Brazil.
ESTEVES1, B.S.; TAOUIL1, A. ; SUZUKI1, M.S.
1 Laboratório de Ciências Ambientais – CBB – Universidade Estadual do Norte Fluminense .
Av. Alberto Lamego, 2000, Pq. Califórnia. Campos dos Goytacazes, RJ, Brazil. CEP:28013-602.
brunosnts@yahoo.com.br; esteves@uenf.br
ABSTRACT:
The coastal Açu lagoon is located in the northern region of Rio de Janeiro State, Brazil, between the latitudes 21º and 22º S and longitudes 40º 57’ and 41º 00’ W. In the north portion of the lagoon, close to the sand bar separating the lagoon from the sea, there is a seasonal growth of opportunist macroalgae, especially Ulva lactuca, generally associated with other red algae. Macroalgae and Ruppia maritima samples were collected from May 2000 to May 2001. Their carbon, nitrogen, phosphate, organic matter, protein and total lipid contents were determined. The seasonal variation of these compounds seems to be correlated to the availability of the inorganic nutrients (N and P) in the water column, especially nitrogen that may be limiting for macroalgal growth in Spring. Variables such as temperature and salinity are strong limiting factors for continuous macroalgal growth in Summer, especially for U. lactuca. Organic matter and protein contents were usually high and evidenced the high nutritional quality of the macroalgae and R. maritima. However, lipid concentrations may be considered as low for high nutritional quality foods item.
Key-words: coastal lagoon; macroalgae; Ulva lactuca; nutritional composition.