Local monitoring program for invasion of zebra mussel (Dreissena polymorpha) in the Dam lake Zhrebchevo, Bulgaria

Zebra mussels (Dreissena polymorpha) are bivalve mollusks approximately 1 to 5 cm long that live in freshwater lakes. They have invaded many Bulgarian freshwater ecosystems in recent decades. Because of their ability to settle on almost any substrate, zebra mussels cause severe damage to closed water systems, RAS and intensive fish farming systems. In order to assess the status of the mussel population in the lake in the area of the Forest group fish farm, the distribution, extent of colonization, abundance, biomass and size-frequency, structure of post-settlement stages were studied in 2012 and 2013. The purpose of this management plan is to identify the spread of zebra mussel colonies in the Zhrebchevo Dam Lake. Zebra mussels in Zhrebchevo Dam lake are category 2+, and 3+ according to the existing classification of abundance, population belongs to the class 6 and hydrochemical parameters have values close to the optimal development of invasive mussels