in: ECOLOGICAL CHANGES IN THE SEA OF MARMARA, Melek İşinibilir,Ahmet E. Kıdeyş,Alenka Malej, Editor, Istanbul University Press, İstanbul, pp.587-633, 2024
Although geographically well apart, there are interesting similarities between the ecosystems of the Sea of
Marmara and the Adriatic Sea. In this study, following an evaluation of the ecological problems as well as
oceanography, productivity, plankton biomass of these seas, macro-jellyfish ecology of the two ecosystems were
discussed comparatively. The Sea of Marmara and the Adriatic Sea are among the areas where increases in jellyfish
and mucilage events have been observed in recent decades. Environmental problems such as global warming, oxygen
depletion, eutrophication, overfishing, intense maritime traffic, and habitat destruction are causing opportunistic and
alien species to increase in both abundance and number of species. As biodiversity declines due to habitat destruction,
so does the ecosystem’s means and ability to combat the invasion of alien species in both ecosystems. Accordingly,
disruption of lower food chains can put pressure on the entire ecosystem and affect socio-ecological prospects. The number of species of Scyphozoa and Ctenophora was found to be higher in the Adraitic Sea compared to the Sea of
Marmara. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for
Aurelia aurita, Rhizostoma pulmo, Chrysaora hysoscella and non-native Mnemiopsis leidyi in the Marmara Sea.
However, although A. aurita and R. pulmo show widespread blooms according to the seasons and regions in the
Adriatic Sea, C. hysoscella and M. leidyi produced blooms limited to a few areas. Negative and positive interactions
of macrojelyfishes with human were also considered. Semi-enclosed seas such as the Sea of Marmara and the Adriatic
Sea are representative of many temperate coastal waters where climate change and anthropogenic stressors are
increasing, and the ecosystem has changed from a fish-dominated to a jellyfish-dominated ecosystem.