Ecological niche of Dreissena polymorpha (Pall.) aggregations in the heated Konin lakes system
Abstract
The zebra mussel, Dreissena polymorpha (Pall.) inhabits various live and dead substrates of the lotic and lentic zones of the heated Konin lakes. Occurring at depths from 20 cm to 3.5 m, this species showed a preference for Unionidae mussels as a substrate. Aggregations of D. polymorpha varied in number from 2 000 to 2 million individuals per m2, while the biomass reached more than 12 kg m-2. The most numerous were one year old mussels 5 mm in length, which comprised from 60-80% of the population. In the preliminary cooling reservoir, newly settled post-veligers comprised as much as 94% of the total of D. polymorpha numbers. The largest mussels did not exceed 35 mm. Aggregations of D. polymorpha contained 49 invertebrate taxa, and the most frequently occurring subdominants were from the Corophidae and Gammaridae families. The diel destruction of organic matter in the aggregations varied between 20 and 370 kJ m-2, depending on the number of animals and their biomass. The turnover coefficient (R/B) in the heated zones was 1.5 times higher, on average, than in the non-heated parts of the system.
