Marian SZATYBEŁKO¹ and Rajmund Dubrawski^2
1 Sea Fisheries Institute, Kołłątaja 1, 81-332 Gdynia, Poland
² Maritime Institute, Abrahama 1, 80-307 Gdańsk, Poland

Key words: overgrowth gear (modules), epiphyte sets, biodiversity, biofiltration effectiveness, deeutrophication, revitalization and cleaning of degraded waters.

Abstract.
Water which is discharged from sewage treatment plants and released into the sea contain significant amounts of pollution which cause environmental degradation. Investigations of the possibilities of utilizing biotechnological methods of pollution removal from significantly degraded marine environments were carried out in the Puck Bay at the D�bog�rze sewage treatment plant water discharge area between 1994 and 1996. Two net modules were used as settlement bases for autochthonous biofilters mainly represented in this areaby mussels (Mytilus edulis L.) and barnacles (Balanus improvisus). Investigations were carried out on the species composition and developmental dynamics of epiphyte fauna and flora sets, physical and chemical changes and sanitary changes in the environment. Water levels of total nitrogen and phosphorus, organic and inorganic suspensions and fecal type MPN E. coli were determined. The magnitude of pollution loads which are removed by epiphyte sets were determined by analyzing the quantitative changes of the investigated components and the speed parameters for the water running through the epiphyte modules. It was discovered that in the area of sewage outflow good conditions for epiphyte set development exist on the surfaces of the net modules. As a result of filtration, trophy is decreased and the sanitary state of the adjacent waters improves.