Jiaozhou Bay Copepods Dominant Species In The Proportion Of Deaths

Planktonic copepods are perhaps the most numerous metazoans on earth and the most important primary consumers in the ocean. Over the last 30 years much effort has gone into examining the growth and fecundity, but only relatively few invesFigations have quantified rates of mortality. Dead proportion of there copepods of Calanus sinicus , Paracalanus parvus and Oithona simili population were invesFigated monthly with neutral red staining method at 12 stations from December 2008 to November 2009 in and around Jiaozhou Bay,China.Calanus sinicus appeared all through the year, with extremely low abundance in summer. Dead females were observed in five months, accounting for no higher than 5% of total female abundance. Proportion of dead females was high in April and November, when total abundance peaked and egg production was most active, but seawater temperature was not exceeding its thermal limits, it was likely that their death was caused by unfavorable temperature , death of females occurred most possibly as reproduction"cost"; Dead copepodites presented in all but three months, with higher proportion from 1.1% to 15.4%. According to correlation coefficient between monthly average of dead proportion and environmental conditions in different areas of the bay, including seawater temperature, salinity and Chl a concentration, dead proportion of copepodites decreased significant with Chl a concentration increase only outside the bay, but negative related to seawater and salinity. Comparing with other studies, the proportion of deaths in this study was noslightly higher than the other station.Paracalanus parvus occurred throughout the year, with a large abundance peak in summer and small peaks in winter. The mean level of dead percent varied between3.8 % and 12.4% for the females (average 6.5%),2.6-11.4% for male(average 6.4%),4.9- 14.1% for copepodites (average 7.2%)all through the year, Dead proportion of adult was significantly lower than that of copepodites .Dead proportion of P .parvus was significantly higher in winter and summer. According to correlation coefficient between average of dead proportion and environmental conditions in different areas of the bay, dead proportion of adult and copepodites were correlation significant correlation with seawater temperature in all bay, higher dead proportion should resulted from seawater temperature exceeding its thermal limits, but it was negative correlation with Cha l and salinity.Oithona similis appeared all through the year, with extremely low abundance in summer. The mean level of dead percent varied between0.7% and7.6%for the females (average 1.7%), 5.5-33.3% for male(average 19.1%),2.9- 8.7% for copepodites (average 4.9%)all through the year. dead proportion of female was significantly lower than that of male observed simultaneously, the deaths of males have 11 times greater than that of female. It is unlikely that these difference can be attributed simply to the males shorter physiological longevity. O.similis is a marine, pelagic, cyclopoid copepod distributed from the subtropics to polar waters, according to correlation coefficient between average of dead proportion and environmental conditions in different areas of the bay, but it was negative correlation with Cha l, seawater and salinity.Our study showed that, the death of these copepods were not significant higher than the other station. It is suggested that environments in Jiaozhou Bay was suitable for living although this semi-closed embayment was usually thought heavily influence by human activities.