Summer epipelagic cladoceran distribution and ecology along the Turkish Mediterranean coast: Spread of the Lessepsian species Pleopis schmackeri
Regional Studies in Marine Science, cilt.102, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 102
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.rsma.2026.105450
- Dergi Adı: Regional Studies in Marine Science
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Zoological Record
- Anahtar Kelimeler: Cladocera, Vertical/horizontal distribution, ecology, Turkish Mediterranean coast
- Çukurova Üniversitesi Adresli: Evet
Özet
Zooplankton constitute a key component of pelagic food webs, facilitating energy transfer to nekton and serving as an important indicator of fisheries productivity. Identifying zooplankton species according to their functional roles helps assess their ecological significance and potential value as bioindicators of pelagic ecosystem conditions. Within this community, cladocerans represent an important prey resource for a wide range of planktonic predators. Using WP2 plankton net (300 µm mesh size), this study investigated the spatial distribution, community structure, and diel vertical migration (DVM) patterns of marine cladocerans within the epipelagic mesozooplankton community along the Turkish Levantine coast during summer (2019) stratification conditions in the eastern Mediterranean Sea. A total of seven cladoceran species from eight marine species were identified, with Penilia avirostris overwhelmingly dominating the assemblage and accounting for 84.3% of total numerical occurrence in all regions. Pseudoevadne tergestina and Evadne spinifera represented the secondary dominant species. Cladoceran abundance and assemblage structure exhibited pronounced regional variability associated with hydrographic conditions, circulation patterns, and coastal processes. The highest regional abundance was recorded in R1, where P. avirostris occurred exclusively, followed by R2, where both secondary dominant species co-occurred with P. avirostris . The lowest abundance was recorded in R4, where P. tergestina was also present. Offshore waters, particularly in region 3, generally supported higher abundances of dominant species, whereas coastal waters contained comparatively higher species richness. Species richness decreased westward across the study area, while diversity and evenness were highest in the Gulf of Antalya due to a more balanced species composition. The spatial distribution of dominant species was closely associated with the Levantine rim current system, localized upwelling–downwelling regions, and thermally stratified waters. DVM analyses revealed significant depth-related distribution patterns for dominant taxa. P. avirostris exhibited active vertical redistribution across the epipelagic zone, migrating below the thermocline during daytime and returning toward upper layers during nighttime. E. spinifera remained primarily concentrated within the surface mixed layer, whereas P. tergestina displayed a vertically separated distribution between shallow and deeper strata. Species abundances were significantly related to environmental variables including temperature, chlorophyll-a, ammonium concentration, density structure, and optical conditions. Multivariate analyses demonstrated significant regional differences in cladoceran assemblages, mainly separating the Gulf of Antalya and western regions from eastern sectors influenced by the rim current system. Canonical correspondence analysis indicated that temperature, pH, salinity, bottom depth, density, and nutrient-related variables contributed substantially to species distribution patterns. The present study highlights the importance of mesoscale circulation, water-column stratification, and environmental gradients in shaping cladoceran ecology in the oligotrophic eastern Mediterranean. It provides baseline information on the biodiversity and vertical dynamics of epipelagic mesozooplankton communities along the Turkish Levantine coast and documents the westward expansion of the Lessepsian species Pleopis schmackeri , which occurred at higher abundances in inshore waters (0.15–21.9 ind. m⁻³). P. schmackeri occupied the entire epipelagic zone, with a deeper distribution during the daytime, followed by an upward migration toward noon and evening and a broader distribution throughout the water column around midnight.