PHYTOPLANKTON Sample Clauses

PHYTOPLANKTON. Analysis of the biomass and taxonomic structure of the phytoplankton of the coastal waters of the North- Western region in 2016, 2107, and 2019 did not reveal significant changes compared to the period 2000- 2012 that occurred after the eutrophication of the 70-80s. This indicates the stable state of theNorth- Western region ecosystem within the last two decades. In the Eastern Central basin, the 3-year average total phytoplankton biomasswas of 9.2 g/m2 which is comparable to the valuesobserved in the Black Sea after the mid-90s (10.6 g/m2). It is 3-times higher than during the period before mid-80s when the eutrophication of the deep basin was minimal (reference period). EMBLAS studies confirmed the previously observed long-term trend towards an increase in the contribution of diatoms and coccolithophores and a decrease in the contribution of dinoflagellates. Thus, the taxonomic structure of phytoplankton biomassclearly differs from that during the reference period. Since the end of the last century, there has been a longer period of mass development of E. huxleyi in the Black Sea (Sukhanova, 1995). Lately, the number of E. huxleyi in offshore areas has reached bloom concentrations every year, and a tendency to increase its abundance has been maintained, which is confirmed by satellite observations (Cokacar et al., 2001; Burenkov et al., 2006). The most intense and prolonged E. huxleyi bloom in the Black Sea was recorded in 2012 (Yasakova & Stanichny, 2012).This phenomenon is thought to be associated with a decrease in eutrophication, with climate changes during recent years (abnormally hot summer early autumn), and with an increase in the phosphate concentration at depth(▇▇▇▇▇▇▇▇▇ et al., 2011, 2013).