Diet Of The Copepod Calanus Sinicus Brodsky, 1962 (Copepoda, Calanoida, Calanidae) In Northern Coastal Waters Of Taiwan During The Northeast Monsoon Period

The calanoid copepod, Calanus sinicus is transported into Taiwanese waters during the northeast (NE) monsoon season, during which time cold waters make incursions into Taiwanese coastal areas. Little is known about the feeding ecology of this copepod. We investigated the gut contents of C. sinicus using scanning electron microscopy (SEM). Samples were collected in northern coastal waters of Taiwan in January 2005. Gut content analysis of copepodites stage V (CVs), females, and males showed a large part of their gut contents as unidentifiable chyme, marine snow, or fragments of phytoplankton. However, C. sinicus fed mainly on diatoms and also a little on protozoans, dinoflagellates, bacteria, and coccoliths. Male dietary gut contents differed in composition from that of CVs and females. Additionally, gut fullness shows a significant difference between CVs, females, and males, with the highest ratio observed in females and the lowest in males. There was an offset in time between gut fullness of male and female copepodites. Thus, we suggest C. sinicus is omnivorous, but this species feeds primarily on phytoplankton with some variations in the course of its ontogeny. In conclusion, C. sinicus adapted rapidly and fed on endemic plankton as its main food source in the waters of Taiwan during the NE monsoon.