Spatial variability of diatoms, subfossil macrophytes, and OC/N values in surface sediments of Lake Väike Juusa (southern Estonia)

The diatom assemblages, organic carbon to nitrogen (OC/N) ratio, and macrophyte remains in surface sediment samples from small dimictic Lake Vaike Juusa in southern Estonia were analysed. The results obtained show that changes in the composition of diatoms, macrophyte remains, and OC/N values are in logical dependence on the water depth in the studied site. So the species richness and number of periphytic diatoms are higher in samples collected in the littoral area, from depths up to 3.5 m. The abundance of macrophyte remains is also higher in the littoral. The OC/N ratio, which reflects the share of planktonic matter in the bulk organic matter, has a tendency to increase from the littoral towards the profundal zone. The data obtained by the three different methods enable to apply this approach to study lake-level change in the past.