The impact of Odra River waters on the seasonal and spatial distribution of primary production and chlorophyll a concentrations in the Pomeranian Bay in 1996-1997

Abstract

Primary production and chlorophyll a concentrations were measured in March and May 1996, July and October 1997. The study was carried out in the coastal zone adjacent to the mouths of the Świna and Dziwna, which together drain over 80% of the waters carried by the river Odra, and in the open Pomeranian Bay. Chlorophyll a concentrations in the entire Pomeranian Bay varied between 0.8 and 16.5 mg m. The minimal daily in situ primary production measured in March was 19.3 mgC m d, the July maximum was 1238.6 mgC m d. The potential primary production ranged from 1.5 to 59.2 mgC m h. The rate of * The studies were sponsored by the Foundation for Polish-German Co-operation’s research project in the Pomeranian Bay. 374 S. Ochocki, H. Chmielowski, J. Nakonieczny, M. Zalewski photosynthesis expressed as the assimilation number (AN) varied from 0.3 to 6.6 mgC mgchl h. The waters of the river Odra reinforce eutrophication in the coastal zone of the Pomeranian Bay. The photosynthetic rate there is usually higher than in open bay waters.