Spatio–temporal variability of diatom assemblages in surface sediments of Lake Peipsi

Abstract

The modern diatom assemblages in surface sediments of large and shallow Lake Peipsi sensu stricto (2611 km 2; maximum depth 12.9 m) in north-eastern Europe (Estonia) were studied. Ordination techniques were used to identify physical environmental parameters (grain size of sediment, water depth and distance from the shore) that explain the distribution of diatoms in the lake. Diatom species distribution and concentration in surface sediment showed large variations (concentrations varied from 3.3 × 10 6 to 149 × 10 6 g −1 dry weight). The texture of surface sediments and concentration of diatoms are highly correlated ( p ≤ 0.05), thus suggesting that the relocation of cohesive particles (silt) due to wind and wave actions affects the spatial variations of diatoms in surface sediments. The diatom data set analysed in the 1970s, and samples taken in 2006 showed some perceptible changes in the composition and concentrations of the diatom assemblages over this time period. However, main dominant diatom taxa have not changed during more than 25 years.