Seasonal sampling between June and November 2023 revealed that Aurelia aurita was the only bloom-forming jellyfish species, exhibiting consistently high abundance at Izmit Bay stations throughout most of the sampling period, and reaching notably high biomass levels between August and October. Phytoplankton composition was dominated by diatoms, particularly Leptocylindrus minimus, and showed high dinoflagellate diversity (Prorocentrum micans, Gonyaulax fragilis), with seasonal peaks driven by temperature and nutrient availability. Zooplankton community dynamics in the Sea of Marmara were shaped by strong seasonal forcing and episodic jellyfish occurrences, promoting a shift toward small filter-feeding taxa such as Cladocera and Appendicularia. Periodic increases in meroplanktonic larvae, particularly Bivalvia and Polychaeta, reflected active benthic recruitment and localized nutrient enrichment in coastal areas (especially at stations M1 and M2). It was determined that C/N ratio of particulate matter (PM) mostly varied between 10-12. This result shows that the source of PM is phytoplankton and therefore the primary production periods. Additionally, the isolation of certain pathogenic bacterial species exclusively from Aurelia aurita specimens suggests that A. aurita may act as a temporary microhabitat for specific bacterial taxa. These findings highlight the critical need for long-term, multi-parameter monitoring of biological and physicochemical factors to improve our understanding and predictive capacity of future dynamics of plankton communities in the sensitive coastal ecosystem of the Sea of Marmara, especially under jellyfish pressure.
| Primary Language | English |
|---|---|
| Subjects | Ecology (Other) |
| Journal Section | Research Article |
| Authors | |
| Submission Date | July 19, 2025 |
| Acceptance Date | October 27, 2025 |
| Publication Date | January 20, 2026 |
| DOI | https://doi.org/10.26650/ASE.2026.1746407 |
| IZ | https://izlik.org/JA75BA25MG |
| Published in Issue | Year 2026 Volume: 41 Issue: 1 |
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