Summer and winter coccolithophore blooms in the Black Sea and their impact on production of dissolved organic matter from Bio-Argo data

Seasonal Stages of Chlorophyll‐a Vertical Distribution and Its Relation to the Light Conditions in the Black Sea From Bio‐Argo Measurements

“…June small local peak of Chla is observed in the same period as the early summer coccolithophore bloom but in deeper layers. In an example in Figure 9 (Stage D-2017), high values of b bp tracing the development of coccolithophores blooms in the Black Sea (see Kubryakov, Mikaelyan, et al, 2019) is marked by yellow color. Such bloom was especially strong in May-June of 2017 (Kubryakov, Mikaelyan, et al, 2019).…”

“…Satellite Chla data help to reveal the key role of the temporal water stratification in the winter pulsing blooms of phytoplankton (Mikaelyan, Chasovnikov, et al., 2017). MODIS satellite scanner measurements of Chla, together with Bio‐Argo data, show the strong impact of storms on the development of anomalous blooms of phytoplankton in the warm period of a year (Kubryakov, Zatsepin, et al., 2019). Long‐term analysis of satellite and in situ data show that the seasonal surface peak of Chla was controlled by river discharge in the shelf areas and by the start of winter convection in the deep areas of the basin (Finenko et al., 2014; Krivenko & Parkhomenko, 2010; Kubryakova et al., 2018).…”

Warmer winters causes an increase of chlorophyll-a concentration in deeper layers: the opposite role of convection and self-shading on the example of the Black Sea

“…productivity not only during winter-spring bloom of phytoplankton, but also in the following months in agreement with the results of previous investigators (Burenkov et al, 2011;Finenko et al, 2014;Mikaelyan et al, 2015Mikaelyan et al, , 2018Kubryakova et al, 2018). In particular, this effect is a probable reason for the unusually strong coccolithophore bloom in May-July 2017, which was documented on the base of satellite and Bio-Argo measurements by Kubryakov, Mikaelyan, et al (2019). In contrast, in deeper layers below 40 m depth Chl in cold 2017 was significantly lower than in warm 2016 (Fig.…”

“…4d). This maximum was investigated in detail in (Kubryakov, Mikaelyan, et al, 2019), where it was related to the release of dissolved organic matter (DOM) after enormously strong early-summer coccolithophore blooms formed due to intense winter convection in 2017. In comparison, in 2016, the values of Kd in 0-40 m in February-October was only about 0.1 m -1 (Fig.…”

“…Large nutrient fluxes in cold winter cause intense spring diatom bloom (Mashtakova, 1985;Sorokin, 2002;Silkin et al, 2014) which is followed by strong coccolithophore bloom (Mikaelyan et al, 2015). The lysis of coccolithophores causes the intense rise of DOM in the upper layer (Kubryakov, Mikaelyan, et al, 2019). Light attenuation decreases the thickness of the euphotic zone and the efficiency of the upward nutrient fluxes in it from the nutricline.…”