Occurrence of Anabaena spiroides (cyanobacterium) in the Patos Lagoon Estuary (RS, Brazil.) in summer-fall of 1998.

Abstract

The present work intended o register the presence and seasonality of Anabaena spiroides in the Patos Lagoon, and its relations with some environmental factors. During 15 months, in situ temperature, salinity, pH and water current were measured at five sites in the Patos Lagoon estuary. Water and microphytoplankton samples were also collected for further analysis. The presence of Anabaena spiroides was confirmed from January to May 1998 reaching 16,250 filaments per liter. Low salinity and high temperature were the main factors associated with the occurrence of the organism in the Patos Lagoon estuary. Anabaena spiroides, a potentially toxic cyanobacteria, did not accumulate as harmful blooms in the estuary, but as the Summer and Fall periods favour the growth of the species, the water at the region may become a risk for recreational and domestic use.