Yunev O. The anthropogenic eutrophication of the Black Sea: quantitative evaluation, mechanisms and its role in the redistribution of organic matter among the main pelagic trophic chains

The work investigates the main aspects of the Black Sea eutrophication that have never been addressed before, namely, the quantitative analysis of the eutrophication and eutrophication mechanisms in the shallow and deep parts of the sea, the main effect of eutrophication on marine ecosystems - its impact on the redistribution of incoming organic matter in the pelagic food web. The work shows the first that in the pre-eutrophication period (1960s) the annual primary production was below 65 g С m-2 yr-1 in most parts of the Black Sea including its deep regions, corresponding of oligotrophic level. We are the first one to use the international oceanographic databases to demonstrate that in the shallow and deep regions of the Black Sea the eutrophication developed in two phases (from the beginning of the 1970s to the mid of the 1980s and from the mid of the 1980s to the beginning of the 1990s), which differed from each other changes in functionally related eutrophication parameters. We further analyzed the role of various natural and anthropogenic factors in the bi-phasic nature of eutrophication. Finally, the work demonstrated that the eutrophication resulted in the dominance of a jellyfish-headed trophic chain, that, despite of the high levels of primary production, determined the low energy level of the present Black Sea ecosystem.