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Research Letters in Ecology
Volume 2008, Article ID 185642, 4 pages
Research Letter

Increased Chlorophyll Levels in the Southern Caspian Sea Following an Invasion of Jellyfish

1Dolmabahce Sarayi, 2 Hareket Kosku, 34353 Besiktas, Istanbul, Turkey
2Mazandaran Fisheries Research Center, Caspian Sea Research Institute in Ecology, P.O. Box 961, Sari, Iran
3European Commission-Joint Research Centre, Institute for Environment and Sustainability, TP272, 21027 Ispra, Italy
4European Commission - Joint Research Centre, Institute for the Protection and Security of the Citizen, TP051, 21027 Ispra, Italy

Received 10 December 2007; Accepted 18 February 2008

Academic Editor: Mark Gibbons

Copyright © 2008 Ahmet E. Kideys et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A significant correlation was observed between satellite derived chlorophyll a (Chl a) concentrations and the biomass of the invasive comb jellyfish Mnemiopsis leidyi in the southern Caspian Sea. By consuming the herbivorous zooplankton, the predatory ctenophore M. leidyi may have caused levels of Chl a to rise to very high values ( 9  mg m 3 ) in the southern Caspian Sea. There might also be several other factors concurrent with predation effects of M. leidyi influencing Chl a levels in this region, such as eutrophication and climatic changes which play major roles in nutrient, phytoplankton, and zooplankton variations. The decrease in pelagic fishes due to overfishing, natural, and anthropogenic impacts might have provided a suitable environment for M. leidyi to spread throughout this enclosed basin.