Carbon and nitrogen stable isotopes of meiobenthos and their food resources

Carbon and nitrogen stable isotope ratios were used to measure the in situ assimilation of Spartina alterniflora and benthic micro-algae by harpacticoid copepods and nematodes. These meiofauna are important food resources for higher trophic levels in estuarine food webs, but little has been known about their natural diets. Meiofauna, detrital Spartina, benthic micro-algae and sediment exhibited no differences between mean seasonal carbon isotope ratios. The δ 13C of populations of harpacticoids and nematodes are similar and indicate the use of similar foods throughout the year. The δ 15N of detrital Spartina and micro-algae were not distinct and did not allow the identification of the source of nitrogen assimilated by the meiofauna. Populations of meiofauna assimilate a mixture of food resources, however, detrital Spartina may be the predominant source of carbon with micro-algae contributing some portion of the assimilated carbon and nitrogen.