Annual Dynamics of Phytoplankton in the Black Sea in Relation to Wind Exposure

Vladimir Silkin,Alexander S Mikaelyan,Alexey Fedorov,Larisa Pautova

doi:10.3390/jmse9121435

Abstract

Studies of the annual dynamics of phytoplankton in the NE Black Sea at two stations on the shelf and the continental slope were conducted in 2016, 2017, and 2019. The species composition of phytoplankton has not undergone significant changes compared to previous decades. The coccolithophore Emiliania huxleyi, small flagellates, and diatoms determined the abundance of phytoplankton; and diatoms, coccolithophores, and dinoflagellates determined the total biomass. The annual dynamics of the satellite-derived chlorophyll-a showed peaks in spring and autumn, and sometimes in summer. During the stratified water column period, strong winds in most cases led to a detectible increase in chlorophyll-a. The annual dynamics of phytoplankton followed the pattern: small diatoms (spring) → coccolithophores (late spring, early summer) → large diatoms (summer, autumn). Such a pattern was typical for the previous decades. Coccolithophores dominated in weak SE winds, diatoms in NE winds. The combined effect of sustained offshore wind and strong current can cause diatom blooms during stratified water, even if the wind velocity is moderate.

Highlights

Marine phytoplankton play a decisive role in the functioning of the biological carbon pump, which is responsible for the transfer of atmospheric carbon to the deep layers of the ocean [1,2]
Our results showed that even a single period of strong winds regularly led to a detectible increase in Chl in the Black Sea
Three-year studies of the annual dynamics of phytoplankton in the northeastern part of the Black Sea have shown: 1. The species composition of phytoplankton has not undergone significant changes compared to previous years

Summary

Introduction

Marine phytoplankton play a decisive role in the functioning of the biological carbon pump, which is responsible for the transfer of atmospheric carbon to the deep layers of the ocean [1,2]. Without identifying the regulators that determine the shift of dominants, it is impossible to understand the basic pattern of the formation of the phytoplankton structure. This task is not trivial since there are seasonal and interannual trends in structural changes in phytoplankton and many potential regulators. This problem can only be successfully resolved with the help of regular and long-term field and remote sensing studies of the annual dynamics of phytoplankton. Light intensity can shift the structure of phytoplankton [12]

Results

Discussion

Conclusion