Composition, structure, and dynamics of communities of fish and decapods off the southern coast of the Crimea (the Black Sea)

Abstract

Under climatic and anthropogenic factors, the Black Sea ecosystem is being transformed and replenished with new species of fish and Decapoda. Therefore, regular monitoring studies become relevant which allow identifying the effect of these processes on biocenoses of the Crimean Peninsula coastal waters. The aim of this work was to investigate taxonomic, structural, and quantitative characteristics of decapods and ichthyofauna of the Black Sea in the area of the Cape Martyan nature reserve. To make the results more complete, both adult individuals and planktonic and larval stages were sampled and analyzed. Fish and decapods were sampled with fixed nets, bottom traps, and hand nets. Ichthyoplankton and Decapoda larvae were sampled with an ichthyoplankton cone-shaped net IKS-80. For decapods, a high level of species diversity was revealed: those were represented by 17 species from 14 families. Two species, Alpheus dentipes Guérin, 1832 and Lysmata seticaudata (Risso, 1816), were recorded in the study area for the first time. The taxonomic composition of ichthyofauna was formed by about 30 species, mostly benthic and demersal fish. The structure of fish communities was quite stable; there was a trend towards an increase in diversity, a decrease in the prevalence of certain species, and an overall improvement in their state. A rise in abundance of some Atlantic–Mediterranean species, such as Serranus scriba (Linnaeus, 1758) and Chromis chromis (Linnaeus, 1758), can serve as an indicator of variations in hydrological and hydrochemical parameters of the environment related to general climate and ecological changes. The values of the quantitative parameters of fish eggs and larvae, (76.3 ± 11.4) and (18.8 ± 4.6) ind.·m−2, respectively, were sufficiently high for the Black Sea coastal waters. However, the proportion of living, normally developing fish eggs in the water area was low, 28.6% of the total. The data obtained can be used for comparative analysis during long-term monitoring in the Black Sea water area.

Keywords

• black sea
• ichthyofauna
• ichthyoplankton
• decapoda
• cape martyan nature reserve