Feeding ecology of three amphipod species Synchelidium lenorostralum, S-trioostegitum and Gitanopsis japonica in the surf zone of a sandy shore

Abstract

The influence of seasonal and ontogenetic changes on the dietary composition of 3 amphipod species (Synchelidium lenorostralum, S. trioostegitum and Gitanopsis japonica) were studied in the surf zone of a sandy shore habitat in Dolsando, southern Korea. The 2 species of Synchelidium were found to be carnivorous feeders, consuming mainly benthic harpacticoid copepods, whereas G. japonica had a diet consisting of both copepods and detritus. The dietary composition of S. lenorostralum and S. trioostegitum overlapped for all ontogenetic stages. Little overlap was found in the dietary composition of G. japonica compared with the 2 Synchelidium species, a characteristic that might favor the co-existence of the 3 species. S, lenorostralum displayed significant differences in dietary composition between sexes, among developmental stages, and over the seasonal cycle. For S. trioostegitum, dietary composition varied over the seasonal cycle. Juveniles of Synchelidium fed mainly on copepod nauplii and nematodes as well as on benthic harpacticoid copepods. Our results suggest that the biological interactions between benthic amphipods and meiofauna, such as benthic harpacticoid copepods and nematodes, may be important in the trophic chain of sandy shore surf zone habitats.