Akademik Veri Yönetim Sistemi
Ecological Changes in the Sea of Marmara, İŞİNİBİLİR OKYAR MELEK,KIDEYŞ AHMET ERKAN,Malej Alenka, Editör, Istanbul University Press, İstanbul, ss.543-572, 2024
The study conducted in the eastern Sea of Marmara from 2016 to 2022 aimed to investigate the spatio-temporal
distributions of mesozooplankton in relation to changing environmental conditions. A total of 43 zooplankton taxa were
identified, with the number of species varying between 4 and 19 in the brackish upper layer (resembling the Black Sea)
and between 1 and 17 in the saline lower layer (resembling the Mediterranean Sea). The abundances of zooplankton
ranged from 28 to 43,359 ind.m-3 in the upper layer and from 5 to 3,851 ind.m-3 in the lower layer. Significant
differences were observed between the upper and lower layers in terms of the number of species, total zooplankton
abundances, evenness, and Shannon diversity (p<0.0001). The most significant differences in zooplankton abundance
and community structure were found to be seasonal rather than inter-year or regional variations. The highest total
zooplankton abundance was recorded at station M14 during the summer season (June 2022), primarily due to the
presence of Paracalanus parvus and Penilia avirostris (906 ind.m-3 and 722 ind.m-3, respectively). The heterotrophic
dinoflagellate Noctiluca scintillans, a major component of net samples in the Sea of Marmara, exhibited a clear seasonal
distribution, with higher abundances consistently observed during winter months. The highest abundance of Noctiluca
scintillans was recorded in February 2016 at station MD102 (42,514 ind.m-3). Paracalanus parvus, Acartia clausi, and
Oithona nana were identified as important year-round species in both the upper and lower layers of the Sea of Marmara.
The presence of N. scintillans and P. avirostris distinguished the upper layer communities from the lower layer, with N.
scintillans being more prevalent during winter and P. avirostris during summer. Notably, P. avirostris exhibited very
low abundances during the summers of 2019, 2021, and 2022. The large-scale mucilage event that occurred in June
2021 had a significant impact on zooplankton, as evidenced by the low abundance and biomass observed during this
period. The chlorophyll-a values, which reflect phytoplankton biomass, increased sharply during the dominating
mucilage event, ranging from 12.2 to 14.2 µg.l-1. Overall, this study emphasizes the vulnerability of the Sea of Marmara
ecosystem, particularly zooplankton, to large-scale environmental disturbances such as mucilage events.