Seasonality of zooplankton in the Southern Black Sea and genetics of Calanus Euxinus (Copepoda)

Ünal, Ebru
Seasonality and composition of zooplankton was comparatively studied at two stations (inshore and offshore) off Sinop, in southern Black Sea in 1999. Intra-specific genetic differentiation of the copepod Calanus euxinus dwelling in different layers along the water column was also investigated in samples obtained from different regions of the southern Black Sea in September 2000. A total of 64 zooplankton species were identified in the Sinop region in 1999, most of which being meroplankton. Out of these, 17 meroplankton species were recorded for the first time along the Turkish coastline. The number of holoplanktonic and meroplanktonic species showed an increase towards summer at both stations. Even though the fodder zooplankton and N. scintillans constituted almost all the total zooplankton (131,093 ind/m) in terms of inabundance, the two together could only constitute 4.7 % of the total in terms of biomass with almost equal shares. Fodder zooplankton constituted as much as 56 % of the total zooplankton abundance, the highest inshore and offshore biomass values being 7,303 mg/m2 in early February, and 14,864 mg/m2 in late September, respectively. Noctiluca scintillans dominated the zooplankton through spring to early summer at both stations. Copepods had no preference between the inshore and offshore stations and existed throughout the year. Meroplankton had a higher preference for the inshore station, reaching peak values in February. The dominant meroplankton species (83-87 %) was Mytilus galloprovincialis. Cladocerans mainly existed during warm months, the dominant cladoceran species being Penilia avirostris (88-97 %). Pseudocalanus elongatus was the most abundant (24 - 38 %) fodder zooplankton species present in this study. Calanus euxinus and Sagitta setosa were the two dominant fodder zooplankton species in terms of biomass, at the inshore (23 %) and offshore stations (35 %), respectively. Reproduction timing was clarified for the most important zooplankton species and interesting competition and predation relationships were revealed. Even though low levels of intraspecific genetic differentiation were recorded for Calanus euxinus individuals (0.2 - 1.0 %) for the 657 base-pair region of the mtCOI gene studied, there were no base sequence differences between the diapausing and migrating Calanus euxinus groups. Therefore, these two groups possibly represent a single population.
Citation Formats
E. Ünal, “Seasonality of zooplankton in the Southern Black Sea and genetics of Calanus Euxinus (Copepoda),” Middle East Technical University, 2002.