오륙도 인근 해역의 동물플랑크톤 군집 변화와 요각류 Oithona similis의 개체군 동태

Abstract

The monthly variations of zooplankton community and population dynamics of Oithona similis were investigated at four stations near Oryuk islets off Busan, South Korea. Zooplankton was collected by using a conical net (45 cm diameter with 200 µm mesh) from near bottom to surface from May 2011 to May 2012. Zooplankton community consisted of 132 taxa including 57 copepoda. Total density ranged from 5,584.7 inds.m-3 in January to 28,335.2 inds.m-3 in November. Copepoda dominated the zooplankton community, reaching 59.8~92.8% of the total density. Acartia omorii, Corycaeus affinis, Oithona similis, Paracalanus parvus s. l., Calanoida copepodite, Copepoda nauplius, Cirripedia nauplius, Podon leuckarti were dominant species. Of these, P. parvus s. l. was most abundant throughout year, accounting for 18.6~69.7% of density of total zooplankton. Except for the density of P. parvus s. l., A. omorii and P. leuckarti were dominant from May 2011 to July; Copepoda nauplius and Cirripedia nauplius from August to October; O. similis and C. affinis from November to January; Calanoida copepodite from February to May 2012. These results suggested that changes of zooplankton community near Oryuk islets off Busan were related with variation of temperature and Tsushima warm current. One of dominant species, O. similis occurred throughout the year, ranging from 5.0 to 31.9% of density of total zooplankton. The lowest density of O. similis was observed to be 179.6 inds.m-3 in May 2011 and the highest density in November with 1557.8 inds.m-3. Density of O. similis was strongly correlated with temperature and had no correlation with salinity. There were more than six generations of O. similis near Oryuk islets off Busan in a year.