Unusual "water-bloom" of large-cell diatoms algae’ species in off-shore waters of Sevastopol in 2007 - 2010 (the Black Sea)
From 1994 to 2010 the complex hydrochemical and biological monitoring of Sevastopol off-shore waters were carried out. The research results showed that in a cold period of year a «water-bloom» was caused by small-cell species of diatoms algae (less than 50 mkm), in a warm period (from April to October) at the decline of concentration of mineral forms of biogenic elements and increase of concentration of their organic forms a «water-bloom» was caused by large-cell species (50 - 1500 mkm). In 2000th due to the increasing of freshwater flow in the Sevastopol bay biomass of large-cell species <i>Dactyliosolen fragilissimus</i>, <i>Cerataulina pelagica</i>, <i>Pseudosolenia calcar-avis</i>, <i>Proboscia alata</i> increased by an order (to 19 - 51 g·m <sup>-3</sup>) compared to 90th years of past century (2 - 6 g·m <sup>-3</sup>). A mass growth of <i>D. fragilissimus</i> and <i>C. pelagica</i> was in a 5-meter layer, ones of <i>P. calcar-avis</i> and <i>P. alata</i> was in the whole water layer, them biomass increased with a depth. In abnormally warm 2009 <i>P. alata</i> vegetated in plankton during whole year causing the early-spring and summer - autumn - winter «water-bloom». The growth of large-cell species in periods with an increased concentration of dissolved organic substance supposes that they have the ability to myxotrophic nutrition.