Long-term variations of thermohaline and hydrochemical characteristics in the mussel farm area in the coastal waters off Sevastopol (Black Sea) in 2001–2018

Abstract

In this work, we present results of the first long-term oceanographic study of the mussel farm area in the brackish oligotrophic coastal waters off Sevastopol (Crimea, Black Sea). The long-term seasonal and annual variations of the thermohaline and main hydrochemical characteristics, their trends and probability distributions are reported. The significant trends are related to the regional climate change and phytoplankton activity. The increased nitrate concentration in the mussel farm surface water as compared with the bottom water and background station surface water is explained by the nitrification in the mussel bed. The obtained trophic index (TRIX) values allow classifying the mussel farm area as the low-trophic region. The area under study is shown to be currently suitable in all parameters for the development of bivalve farming, but the negative trend of the silicate concentration observed in this work may lead in the future to the phytoplankton depletion and to disastrous consequences for the bivalve aquaculture in the southwest of Crimea.