Feeding impact of the planktonic copepod Calanus sinicus on phytoplankton in the northern East China Sea in late spring

Abstract

The distribution and feeding of Calanus sinicus were studied in June 2015 on the 12 sampling stations spread from the southern coast of Korea to the northern East China Sea, to better understand an ecological role of C. sinicus in the research area. Ingestion rate, daily ration as percentage body weight and feeding impact of copepodite stage CIV to adults were estimated using the gut pigment method. Density of overall C. sinicus was varied from 2 to 1,387 inds. m-3 by stations. CV copepodite was the most abundant with the density of 273.7 inds. m-3 and CIV was next, followed by adult female and male. The gut pigment content of the copepodites of C. sinicus ranged from 3.2 to 5.5 ng chl. ind-1 with the highest value in the adult female. Although the gut pigment content and ingestion rate of adult female were higher than other developmental stages, the highest value of daily ration as percentage body weight was found at CIV copepodite. These results confirm that the feeding of copepodites of C. sinicus is more active than that of adults. Mean feeding impact of the copepodites of C. sinicus on phytoplankton biomass, in terms of chlorophyll a concentration, ranged from 0.1 to 2.6% with the highest value in the copepodite CV. No significant correlations was found between density, ingestion rate and feeding impact of C. sinicus and the environmental factors such as temperature, salinity or chlorophyll a concentrations.rch area. Ingestion rate, daily ration as percentage body weight and feeding impact of copepodite stage CIV to adults were estimated using the gut pigment method. Density of overall C. sinicus was varied from 2 to 1,387 inds. m-3 by stations. CV copepodite was the most abundant with the density of 273.7 inds. m-3 and CIV was next, followed by adult female and male. The gut pigment content of the copepodites of C. sinicus ranged from 3.2 to 5.5 ng chl. ind-1 with the highest value in the adult female. Although the gut pigment content and ingestion rate of adult female were higher than other developmental stages, the highest value of daily ration as percentage body weight was found at CIV copepodite. These results confirm that the feeding of copepodites of C. sinicus is more active than that of adults. Mean feeding impact of the copepodites of C. sinicus on phytoplankton biomass, in terms of chlorophyll a concentration, ranged from 0.1 to 2.6% with the highest value in the copepodite CV. No significant correlations was found between density, ingestion rate and feeding impact of C. sinicus and the environmental factors such as temperature, salinity or chlorophyll a concentrations.