Long-term changes in the status of Sevastopol Bay and the Crimean coast: anthropogenic and climatic influences

The Black Sea as a whole is subject to considerable anthropogenic and natural pressures, and these can be intensified in enclosed Bays such as those around the city of Sevastopol. The overall biological status of Sevastopol Bay has improved considerably in the last 30 years or so. The number of macrobenthic species in the Bay has increased from just over 20 in 1973 to around 70 in 2000, and there have been similar enrichments in abundance, in biomass and in diversity (H′). The same pattern is shown in other locations such as the Southern Bay (the most highly polluted of the embayments) from which macrofauna were completely absent in 1976 and 1982. Over the same period oil hydrocarbons in sediments of the Southern Bay have actually increased from 8760 mg kg⁻¹ in 1976 to 12,020 mg kg⁻¹ in 2002, while the levels in the open sea sediments have decreased slightly over the same period (450 mg kg⁻¹ and 280 mg kg⁻¹, respectively). Moreover, this pattern of biological improvement is also seen outside the Bay, suggesting a common factor in the changes. Since the effect of the local factors (i.e. pollution) can be readily seen in the gradient of biological response among sites, yet they have not significantly changed over the period of study, the overall improvement must involve some over-arching driver such as climatic influences. This point is discussed further in relation to the wider changes in the Black Sea system. Guest editors: J. Davenport, G. Burnell, T. Cross, M. Emmerson, R. McAllen, R. Ramsay & E. Rogan Challenges to Marine Ecosystems