Phytocene state in the russian part of Curonian Lagoon of the Baltic Sea in conditions of anthropogenic eutrophication and global climate warming

Abstract

Long-term researches of phytocene, chlorophyll “a“ an hydrochemical water composition made in the Russian (southern) part of Curonian Lagoon on the eve of 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> and 21 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> centuries (1989-2001), revealed significant changes occurred in the community condition under the impact of anthropogenic eutrophication and global climate warming, observed in 1930s, 1950s, 1970s and 1980s. The structural reorganization was manifested in the remarkable increase of species diversity, including toxic species, caused by appearance of the species more tolerant to unfavorable environment conditions. The Shannon's index of species diversity increased, active vegetation of Cryptophyta was observed and Cyanophyta occupied the leading position. Partial replacement of dominating species and biomass indices increase were observed. The summer maximum amplitude became higher than that of spring. The third autumn peak, never observed in 1979s, appeared in October. The extension of phytoplankton vegetative period was found. The Lagoon waters are classified as poly-hypertrophic, and in anomalous years - as poly-trophic, while in 1970s they were eutrophic. The water quality is considered as satisfactory (Class III).