Zebra mussels for water quality improvement

Curonian Lagoon, Lithuania

The zebra mussel Dreissena polymorpha is a filter-feeding colonies forming bivalve known to be present in the Curonian Lagoon for at least 200 years and highly abundant in the central part of the lagoon.
The results of a pilot study have shown that larvae of zebra mussels are available in the central part of the Curonian Lagoon from late May to early August in relatively high numbers (up to 500 ind/l).

Up to 4 kg of mussels per m² could be harvested after one cultivation season (May–October). Meat content of mussels is about 16% wet weight (up to 40% for young mussels). Concentration of toxic compounds in zebra mussels is well below the regulatory limits and much lower in young mussels comparing to bigger ones.

A promising addititional remediation measure

The water quality of the highly eutrophicated Curonian Lagoon (with transparency range between 0.3 and 2.2 m and seasonal Chl a fluctuations up to 450 μg/l) cannot be sufficiently improved through river basin management alone. Hence zebra mussel cultivation in the Curonian Lagoon could be a promising addititional remediation measure and serve as a point-source filter reducing nutrient outflow to the Baltic Sea. Based on the results of the pilot study and taking into account the specific environmental conditions of the lagoon (shallowness, hydrodynamic regime, pronounced seasonality, ice cover in winter and ice drift in spring) we suggest seasonal zebra mussel farming as the most appropriate approach in the Curonian Lagoon.