بررسی پراکنش و تراکم فصلی زئوپلانکتون ها در سواحل شمالی دریای مکران

The purpose of this study was to investigate the zooplankton population of eastern coasts of Chabahar and northern Makran Sea during ۲۰۱۷-۱۸. Sampling was carried out using a ۱۰۰ μm mesh Zooplankton cone net with a ۳۰ cm opening diameter in horizontal span at ۸ stations in Chabahar, Beris and Rimini Bay during four seasons from summer ۲۰۱۷ to spring ۲۰۱۸. Physicochemical properties of water were measured including temperature, salinity, pH and transparency at each sampling station. According to one-way ANOVA, there were no significant differences between the different seasons in transparency (p> ۰.۰۵). Significant differences were observed for the temperature, salinity and pH factors between the different sampling seasons (p <۰.۰۵). In this study, ۱۰ classes of zooplanktons were identified. The Copepoda accounted for ۶۶.۸۷% of the zooplankton population followed by Bivalves (۷.۵۳%), Thaliacea (۶%), and Polychaeta, Cephalochordata, Ostracoda (۲.۲۲%). The minimum zooplankton density was observed in winter with an average of ۸۷۶.۵۲ ± ۴۱.۶۲ individuals per cubic meter of water and the maximum density in autumn with an average of ۱۳۳۹.۹۳ ±۴۱.۱۶ individuals per cubic meter of water. Also, a significant positive correlation was observed between zooplankton density and temperature (r= ۰.۶۲۸, p = ۰.۰۰۰۱) or salinity (r=۰.۳۹۱, p = ۰.۰۲۷). According to the results, the structure of zooplankton communities in this region seems to be influenced by the changes caused by monsoon winds and coastal currents. Thus the production cycle and seasonal fluctuations of zooplankton depend on the response the environment exhibit to these changes. As a result, when zooplankton are exposed to severe disturbance (monsoon), several species become dominant species and reduce species homogeneity.

Keywords:

زئوپلانکتون , خلیج چابهار , تراکم , دریای مکران