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.KEY WORDS: Synchelidium lenorostralum · S. trioostegitum · Gitanopsis japonica · Amphipoda · Feeding · Sandy surf zone Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 258: [189][190][191][192][193][194][195][196][197][198][199] 2003 sandy shore habitats, often dominating benthic macrofaunal communities in terms of both numbers and biomass (Fenchel et al. 1975, Wijnsma et al. 1999, Dittmann 2000. Moreover, amphipods are considered to be one of the most important secondary producers (Carrasco & Arcos 1984) and a major food source for a variety of marine predators (Kline & Wood 1996, Schlacher & Wooldridge 1996, Beare & Moore 1997, MacNeil et al. 1999, Takahashi et al. 1999. Amphipods play an important role in surf zone food webs, acting as a trophic link from primary producers to higher-order consumers. Clearly, quantitative assessments of trophic relationships between amphipods and their prey/predators are important for our understanding of energy flow in sandy shore surf zone environments (Gerdol & Hughes 1994).Various aspects of amphipod feeding activity have been studied, including diet (Fenchel et al. 1975, Biernbaum 1979, Nielsen & Kofoed 1982, Icely & Nott 1985, Stuart et al. 1985, diel feeding patterns (SainteMarie 1986, Gerdol & Hughes 1994, Ingolfsson & Agnarsson 1999) and the influence of food quality on growth and reproduction (Gee 1988, Johnson & Wiederholm 1989, Delong et al. 1993, Pöckl 1995, Poltermann 2000. These studies have provided basic information on the feeding ecology of freshwater and marine amphipods inhabiting sublittoral and intertidal habitats. However, there is no information available on the feeding characteristics of amphipods in sandy shore surf zone habitats.In the s...

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