Zooplankton Community Structure at the İskenderun Bay (Northeastern Mediterranean Sea) in 2016

Introduction: Inshore areas are very sensitive systems in which hydrographical values change rapidly. These sharp changes are reflected in zooplankton communities. In this respect, the status of zooplankton populations at the west inshore area of İskenderun Bay in 2016 was investigated in the present study. Material and Methods: The present study was conducted seasonally at five stations between April and December in 2016. Zooplankton samples were collected using with WP-2 net (200μm messh size). Zooplankton abundance was determined as individual per -3 -3 m and zooplankton biomass was measured as dry weight per m . Temperature and salinity were measured using YSI 650 CTD probe at the surface and depths of 5m., 10 m. and 15 m. Chlorophyll-a and phytoplankton abundance were obtained from water samples taken simultaneously at the same depths using a Niskin water sampler. The spearman rank correlation was applied to estimate relationship between environmental factors. Results and Discussion: The annual mean abundance and biomass of the zooplankton -3 -3 were 2723±1505 ind. m and 9.02±4.73 mg m , respectively. These values changed -3 -3 seasonally and the lowest values were seen in winter (523 ind. m , 2.3 mg m ), and the -3 -3 highest values were observed in the spring (6210 ind. m , 18.1 mg m ). Two major peaks in zooplankton abundance were observed in the spring and summer. The first zooplankton biomass peak occurred in spring, similar to the abundance peak, however, the second peak was observed in autumn instead of in summer. Fourteen meroplankton and 13 holoplankton groups were identified in the study area. Cladocera was the dominant group in summer, whereas Copepoda had the highest abundance during the other seasons. Other common zooplankton groups were Appendicularia, Bivalvia Cirripedia Echinodermata, Doliolida, Chaetognatha, Hydrozoa, Doliolida, Appendicularia, and Polychaeta. The contribution of these groups varied seasonally. The proportion of meroplanktonic groups was higher in the spring and summer. Zooplankton abundance was significantly correlated with temperature, salinity, and trophic elements (diatom and dinoflagellate abundance)