Role of bivalves in the phosphorus and nitrogen budget in lakes

Abstract

Dreissena polymorpha (Pall.) is one of the most numerous mussels in littoral of lakes, and certainly the most important one regarding the biomass. Their role in water ecosystems is, since a long time, considered to be important. In the last years a special role is attributed to their filtration activity (Wiktor 1969; Stanczykowska 1977; Walz 1978). Mass appearance of mussels and their intensive filtration activity may also remove from the ecosystem, for the considerable period of time, an amount of P and N, the elements highly responsible for the process of lakes eutrophication

The question arises, whether mussels occurring in lakes in such great numbers as D. polymorpha may be of importance in counteracting the process of lakes eutrophication. In what type of lakes its role is the most important?

The studies related to this problem were carried out in meso- and eutrophic lakes of Masurian Lakeland: 5 lakes of Jorka R. watershed (Stańczykowska & Planter in prep.), Mikołajskie Lake and Tałtowisko Lake (Stańczykowska unpubl.), in which the parameters of D. polymorpha population (density, biomass, age structure) were estimated. The content of N and P in mussel body, shell, as well as in the food (seston) and the faeces was measured. A comparison of mussel occurrence in dimictic and polymictic lakes with various P concentration in epilimnion was made for 42 lakes (Stańczykowska et al. 1983).