THE INFLUENCE OF WATER MASS DYNAMICS ON THE CHANGES OF INVERTEBRATES NUMBER IN LAKE GARDNO

Abstract

Gardno is an estuarial, b-oligohaline, coastal lake separated from the Baltic Sea by a narrow strip of a land. This shallow reservoir is strongly exposed to the wind due to its large area. Factors above  result in frequent and easy mixing of water mass. The wind, and exactly water movements caused by the wind in such a shallow, polymictic reservoir, is the main factor limiting the number and species diversity of invertebrates.

The aim of the study is to estimate the influence of abiotic factors on changes of invertebrates abundance in Lake Gardno. The material was taken at six sites. Biological material was collected and divided into three taxonomic groups of zooplankton (Rotatoria, Cladocera, Copepoda) and five zoobenthos taxonomic groups of different systematic importance (Chironomidae, Oligochaeta, Gastropoda, Bivalvia, Trichoptera, Amphipoda).

There is a significant relationship between zooplankton communities (Cladocera, Rotatoria) and physical factors (0.8846), a weaker relationship was observed between the dynamics of Oligochaeta and Copepoda number (0.6351). The significant influence of the wind velocity and water temperature  on the occurrence of Oligochaeta and Copepoda was found. The negative relationship appeared  between the number of chironomids larvae and other components of the analysis (-0.4412).

Key words: zooplankton, zoobenthos, coastal lakes, abiotic factors;