Phytoplankton development in a highly eutrophic lake from pampa?s plain: functional approach.

FERNÁNDEZ, C; PARODI, E. R; CÁCERES, E. J.

Rodas

Congreso; Fifth European Phycological Congress; 2011

British Phycological Society

PHYTOPLANKTON DEVELOPMENT IN A HIGHLY EUTROPHIC LAKE FROM PAMPA?S PLAIN: FUNCTIONAL APPROACHCarolina Fernández1 (carofer@criba.edu.ar), Elisa R. Parodi1,2 (eparodi@criba.edu.ar) and Eduardo J. Cáceres2 (uscacere@criba.edu.ar)1CONICET-CCTBB-IADO; 2DBByF-UNS. Bahía Blanca, ArgentinaDuring its annual development, phytoplankton communities undergo changes in both their quantity and specific composition. The most frequent species of a specific environment share common suitable attributes and they constitute assemblages that reflect autecological aspects of preference and tolerance. The present study aims to further knowledge of phytoplankton development in an hypereutrophic polymmictic reservoir from the Pampa?s plain (Paso de las Piedras Reservoir, Argentina) and in particular (1) to validate the Reynolds? classification scheme and (2) to analyze the phytoplankton structure and dynamics in terms of functional groups in relation to abiotic variables. We carried out weekly or bi-weekly monitoring from January 2004 to June 2005 at two sampling stations (S1 and S3). Ascribing the descriptive species to the associations outlined by Reynolds we found 15 of the proposed functional groups, these groups together accounted for more than 80% of the total biovolume during all the study period. The majority of the associations were typical of eutrophic-hypertrophic systems. Functional groups D, P, H1, F, J and C were the most important. With the exception of H1, all the dominant groups were characteristics of mixed environments. Sampling station S3 showed higher values of biovolume, there were also differences in the relative contribution of some groups to the total biovolumen, since in S1 there was a major contribution of J group whereas in S3 there was a major contribution of K and H1 groups. In the same way, during July and August the major contribution to the biovolume in S1 was accounted for group C whereas at S3 was accounted for D. The CVA indicated that the functional groups were significantly more probable than random groups in both stations. The multivariate RDA showed that water temperature, reactive soluble phosphorus concentration and N:P ratio explained a significant proportion of the functional group variation.