The results presented consist of data obtained from the analysis of sediment cores collected in March and July 1996 and in May 1997 from a sampling site located in the southern part of the Pomeranian Bay (Southern Baltic), in an area directly affected by freshwater discharge. The nematodes were identified to the genus level and assigned to appropriate trophic groups; changes in vertical distribution of nematode genera and trophic groups were followed as well. Nematodes were the major component of the meiobenthos at the study site, contributing more than 90% to the total meiobenthic abundance. The nematode abundance varied from about 1646 ind./10 cm2 (March 1996) to about 3452 ind./10 cm2 (July 1996). A total of 35 nematode genera were identified. Sabatieria was the most abundantly represented genus, accounting for from 23 to 32% of the total meiofaunal abundance and from 40 to 55% of that of the nematodes. The highest nematode genus richness was observed in the surficial sediment layers: 0-1cm (July 1996, May 1997) and in 2-3 cm (March 1996). The deeper sediment layers showed a clear reduction in nematode density, genus richness, and trophic diversity. The Sabatieria nematodes, representing the non-selective deposit feeders, were found to have penetrated the sediment to the deepest layers. Non-selective deposit feeders were found to dominate the nematode fauna throughout the period of study (60-80% of the total nematode abundance). The abundance of epistrate feeders and predators/omnivores increased in May 1997 and in July 1996, compared to March 1996, to about 20 and 11-16% of the total nematode abundance. The contribution of selective deposit feeders was low throughout the period of study (2-6% of the total nematode abundance). The results demonstrated the importance of freshwater discharge-associated sediment organic enrichment in the southern part of the Pomeranian Bay for the nematode taxocoene structure.

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