ABSTRACT: We examined the potential for interspecific differences among meiobenthic copepods in their exploitation of microalgal food resources in a natural benthic community. The feeding behaviors of Coullana sp., Cletocamptus deitersi, Microarthridion littorale, and Pseudostenhelia wellsi were examined using ¹⁴C-radiotracer grazing experiments and gut-pigment analyses. In one grazing experiment, laboratory-cultured microalgae were labeled using NaH¹⁴CO₃ and injected into intact sediment cores to determine whether copepods were grazing on algae from the water column and/or at the sediment-water interface. In another grazing experiment, NaH¹⁴CO₃ was injected directly into sediment cores and grazing on ¹⁴C-labeled natural algae was measured. Fluorometric analyses of gut-pigments were used to determine the recent feeding histories of copepods. Functional responses of copepod feeding to variation in sedimentary chlorophyll (chl) a concentrations were also used to discern interspecific differences in feeding. Coullana sp. grazed on microalgae from the water-column and at the sediment-water interface. C. deitersi grazed predominantly on microalgae from the sediment-water interface. Grazing on laboratory-cultured algae was minimal in M. littorale and P. wellsi, but grazing experiments with ¹⁴C-labeled natural algae and gut-pigment analyses indicated that these copepods grazed on microalgae in the field. However, a positive functional response to chl a concentrations by M. littorale and a lack of a functional response by P. wellsi suggest that these 2 species exploit algal resources differently. Collectively, our observations indicate that each copepod species examined exploits microalgal resources differently.

KEY WORDS: Meiofauna · Grazing · Microalgae · Harpacticoid copepods · Cletocamptus deitersi · Pseudostenhelia wellsi · Microarthridion littorale · Coullana sp.

Published in MEPS Vol. 143 (1996) on November 14
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996