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Analysis of 59 surface sediment samples from the Polish exclusive economic zone (EEZ) shows that Szczecin Lagoon sediments are the most polluted by heavy metals and that the degree of heavy-metal pollution decreases substantially on passing from the Szczecin Lagoon to the Pomeranian Bay and the inner shelf area and then on passing to the Bornholm Deep and Słupsk Furrow. Heavy-metal pollution in the sediments of the western part of the Polish EEZ therefore appears to follow the dispersion of the Oder River. Fluffy material from the Oder estuary appears to be the main source of heavy metals in the muddy sediments of the Bornholm Deep. The formation of sulphides is therefore not the principal factor controlling the enrichment of heavy metals in the sediments of this anoxic basin, although it may be responsible for the uptake of Mo, Sb and As. Two main factors control the distribution of the rare earth elements (REE) in sediments of the Polish EEZ: the input of Fe-organic colloids from rivers and the presence of detrital material in the sediments. [ABSTRACT FROM AUTHOR]

Long-term changes in the macrofauna of the Pomeranian Bay were studied by comparing survey data from the 1950s, 1980s, and 1990s. The study area has undergone significant eutrophication during the period of investigation. Biomass of filter-feeding bivalves increased significantly. Spatial distribution patterns of several species have changed. Strong decreases in species richness were caused by oxygen depletion at stations deeper than 15 m. Saduria entomon, Monoporeia affinis, and Pontoporeia femorata vanished entirely between 1981 and 1993. Although a causal relationship between simultaneous increases of nutrient levels and macrobenthic biomass cannot be verified, eutrophication is proposed to be the major process affecing changes in macrofauna assemblages. In addition, changes in hydrography and climate increased frequency and severity of oxygen depletion events in the Pomeranian Bay since the mid 1980s. [ABSTRACT FROM AUTHOR]