Potentially harmful phytoplanktonic species and water quality of oyster reef managements in Bahía Anegada (Argentina)

MARIA EMILIA CROCE; MARIA CECILIA GAUNA; MÓNICA E. BORGES; ELISA R. PARODI

Bahia Blanca

Congreso; ECSA44; 2008

CONICET-UNS

La existence of potentially harmful phytoplanktonic species in Bahia Anegada shores capable of modifying quality and characteristcs of water showed the necessity of analyzing their populations dynamics in response to abiotic parameters, in order to provide information for the oyster reef managements developed in this bay. the studied species were: Asterionellopsis glacialis, Ceratoneis closterium, leptocylindrus minimus, Rhizosolenia setigera and Pseudo-nitzschia spp., dinoflagellates alexandrium sp., Dinophysis sp., Gymnodinium sp., Prorocentrum sp. and Protoperidinium sp. and cyanophytes Synechicystis sp., Agmenellum quadruplicatum and Anacystis montana. In the three sites (SB1, SB2, LP) diatoms accounted for the most part to the totla monthly phytoplnktonic abundance. They were low frecuente and scarce in summer, increased in autumn until a winter maximum. Cyanophytes caused autumn and winter blooms only in Sb1. Dinoflagellates were low frequent, increased their abundance in spring but never were dominant. Cylindrotheca closterium was the most frequent species with high abundance almost the whole year. Asterionellopsis glacialis reached its higher abundances from March to August and was absent in summer. Leptocylindrus minimus was abundant in September like has benn recorded on another coasts of the world. The group Pseudo-nitzschia spp. showed high annual accurrence but without alarming densities. rhizosolenia setigera was occasional, appearing in low abundance just in winter. Spermatozopsis sp. blooms in June and August 2006 caused a reduction of nitrogen availability, with an important increase of the latter when these blooms finished. Gymnodinium sp. reached high densities also in June 2006 in SB1.