Seasonal and interannual dynamics of diatom assemblages in Sacrower See (NE Germany): a sediment trap study

Diatom assemblages from sediment trap samples collected during ten intervals between October 2003 and October 2005 in Sacrower See (NE Germany) were related to limnological and meteorological data. Sacrower See is a dimictic, 38 m deep, hypertrophic lowland lake (29.5 m a.s.l.). We identified distinct seasonal and interannual changes of diatom assemblages for the studied period. Diatoms showed a typical seasonal succession for temperate, dimictic, and eutrophic lakes. Stephanodiscus parvus, S. hantzschii, S. neoastraea, and S. alpinus had high accumulation rates during winter and spring, whereas species of the genera Stephanodiscus, Fragilaria, and Nitzschia were the predominant diatoms during summer and autumn. In a Canonical Correspondence Analysis, precipitation, air and water temperatures, epilimnetic calcium, pH, and total phosphorus concentrations together explained 70% of the variance of the diatom data. Interannual variability in the diatom assemblages during the two sampled years mainly seems to reflect changes in the total phosphorus concentration and temperature and secondarily the onset of the growing season and of stratification. Handling editor: J. Saros