Mollusks are a prospective food for the world’s growing population, but the contents of toxic and essential trace elements in them have not been studied comprehensively. In this work, using inductively coupled plasma mass spectrometry, the contents of 72 elements in soft tissues of the edible mollusks Mytilus galloprovincialis, Rapana venosa, and Crassostrea gigas from the coastal area of the southwestern Crimea were estimated and compared with the maximum permissible levels. Element accumulation similarities were observed in the two bivalve species. Cluster analysis applied to the non-normalized contents allowed finding an optimal number of non-overlapping element clusters: 1 group of macroelements, 1–2 groups of trace elements, and 1–2 groups of ultratrace elements. As an outcome of this analysis, the element accumulation universality index was introduced, which demonstrated the accumulation universality decrease in the order: mussel > sea snail > oyster. An original approach to estimating the mollusk consumption rate was proposed to assess human health risks. Two possible consumption scenarios were identified for Crimean residents. From the expected consumption of all species in both scenarios, there are no health risks, but they are not excluded, within the 95% probability, from high consumption of mussels and sea snails in the pessimistic scenario.

Bioindication of organic pollution and seawater quality was carried out for the first time in the western part of the Sea of Azov on the basis of species composition and quantitative characteristics of microphytobenthos. A total of 229 algal samples were collected at 17 sites over the period of 2005-2014 on three different substrates in three areas under study: Sivash Gulf, the Kerch Strait and Cape Kazantip. In total, 200 taxa of algae were found, which belong to six taxonomic divisions with a predominance of diatoms. Among those, 108 taxa are indicators of substrate, water temperature, salinity, water pH, trophic state, the type of nutrition and organic pollution of water. It has been shown that the most active self-purification of water takes place in communities on stony substrates. The largest number of algae species (50%) occurs in the cleanest waters of the Kazantip Nature Reserve (Water Quality Classes I–II). The species composition of organic pollution indicators in Sivash Gulf corresponds to waters of Classes III–IV, which are more polluted than those of the Kerch Strait and Cape Kazantip. All the studied areas of the Sea of Azov are cleaner compared to some waters of the Eastern Mediterranean and the Sea of Japan.