Primary production comparison between phytoplankton and periphyton in two shallow lakes from Argentina

RODRÍGUEZ, PATRICIA; VERA, M. S.; PIZARRO, H.

St. John´s, Newfounland, Canadá

Congreso; 2008 ASLO Summer Meeting, Interactions on the Edge, St. John's, Newfoundland, Canadá, 8-13 Junio 2008; 2008

American Society of Limnology and Oceanography (ASLO)

Phytoplankton and periphyton production were assessed in two lakes from the Paraná floodplain (Argentina). The study was carried out monthly during 2006-2007 in Grande lake (GL), free of floating macrophytes (FM) and an oxbow lake (OL) 100 %; covered by FM from winter onwards. P-I curves were performed employing 14Cmethodology. In GL, maximum photosynthetic rate (Pmax) and assimilation number (PBmax) were always significantly highest for phytoplankton; similar trend was observed for light efficiency. Light limitation was not observed after spring, neither phytoplankton nor periphyton. In OL there were no significant differences between communities in terms of photosynthetic parameters; phytoplankton was light limited since winter to summer, with 100 % FM coverage and periphyton was light limited in winter. Pmax and efficiency were significantly highest in GL, however no differences were observed comparing these parameters normalized to chlorophyll a. There were no differences among periphyton parameters at both lakes. Phytoplankton productivity in OL was higher than in GL before FM development and lower after it. Phytoplankton would be better adapted to restricted light conditions than periphyton probably owing to buoyancy and motility.