Photobehaviors of the calanoid copepod Calanus sinicus from the Yellow Sea to visible and UV–B radiation as a function of wavelength and intensity

Abstract

The effects of wavelength-specific visible light, white light, and ultraviolet-B (UV-B, 280-315 nm) on selected behaviors, grazing rate, spawning rate, and hatching rate of the marine copepod Calanus sinicus collected from the Yellow Sea were studied. Calanus sinicus placed in a partitioned experimental system responded positively phototaxis to blue-cyan and yellow light but negatively to orange light and UV-B. No obvious dodge activity was found among C. sinicus irradiated with 0.10 mW/cm2 UV-B, whereas yellow-red light stimulated grazing. Egg production rate was highest at a white-light intensity of 1.58 mW/cm2, with an average rate of 10.04 eggs/(female·d). These results are consistent with the observed phenomenon that C. sinicus in the Yellow Sea mostly spawn near dawn. Our results indicate that light intensity and spectrum are important factors affecting the diel vertical migration of C. sinicus under natural conditions in the Yellow Sea.