Annual Occurrence of Calanus sinicus Carcasses in the Jiaozhou Bay and the Adjacent Waters
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Annual Occurrence of Calanus sinicus Carcasses in the Jiaozhou Bay and the Adjacent Waters WANG Shiwei1), 2), 3), #, WAN Aiyong1), 2), 3), #, ZHANG Guangtao1), 2), 3), 4), , and SUN Song1), 2), 3), 5) 1) Jiaozhou Bay Marine Ecosystem Research Station, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China 2) Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China 3) Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China 4) University of Chinese Academy of Sciences, Beijing 100049, China 5) Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China (Received November 4, 2019; revised January 6, 2020; accepted April 28, 2020) © Ocean University of China, Science Press and Springer-Verlag GmbH Germany 2020 Abstract The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November 2009. C. sinicus could be observed through the whole year, with an evident numerical peak from February to April and an extremely low abundance in summer. Annual variation of the dead proportion differed greatly between adult females and copepodites. Dead females were observed only in the southern part and outside the bay sporadically in five months, when the egg production was the most active. Dead proportion of females was usually less than 5%. Dead copepodites could be observed in all but three months in summer in the whole study area, and the proportion varied between 3.8% – 18.2%. Death percentage of copepodites increased significantly in the northern part in January and June, when water temperature exceeded it’s favorable limits; however, the fluctuated salinity had no significant effect on the survival of both females and copepodites. Thus the dead proportion of C. sinicus was relatively low in the Jiaozhou Bay, while difference could be observed between females and copepodites. Dead copepodites were common in all samples, but dead females were presented mainly as ‘reproduction cost’ during generation alternation. Key words dead proportion; Calanus sinicus; Jiaozhou Bay; natural mortality; population dynamics
1 Introduction Planktonic copepods, which might be the most numerous metazoans on the earth, play an important role in transferring the organic matters fixed by primary producers to higher trophic levels (Ohman and Hirche, 2001). Understanding the factors that regulate its population dynamics is very important in biological oceanography. Seasonal and spatial patterns of copepods abundance are shaped by the accumulation of growth and egg reproduction as well as losses through mortality. Over the last 30 years many efforts have been put in examining the growth and fecundity, while only a few investigations have quantified the rates of mortality (Hirst and Kiørboe, 2002). Fur
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