Inter-Research
Marine Ecology Progress Series

ABSTRACT: Modifications to a conventional elemental analyzer-stable isotope ratio mass spectrometer system (EA-MS system) are described that allow the analysis of ¹³C and ¹⁵N in small samples (≥1 µgN and 2 µgC). This system was to analyze d13C and d15N of meiofaunal species from a coastal marsh using pooled samples of 5 to 60 individuals. In a conventional field survey, ¹³C and ¹⁵N isotope values indicated that (1) harpacticoid copepod species, nematode species, and ostracods differentially exploited phytoplankton detritus, Spartina alterniflora detritus, and benthic microalgae, and (2) all taxa showed a general shift toward S. alterniflora isotope values in winter relative to summer. In a field experiment, benthic microalgae were labeled in situ by addition of ¹³C and ¹⁵N to 1 m² sediment plots. Two nematode species with apparently similar primary food resources (S. alterniflora detritus) based on natural isotopic values differed dramatically in their uptake of ¹³C and ¹⁵N in labeled plots, indicating differences in feeding strategies that were not indicated by natural isotope values. A combination of natural-abundance isotope surveys and isotope-addition experiments appears to be a powerful approach for investigating both average patterns and interspecific variability in resource exploitation.

KEY WORDS: d13C · d15N · Meiofauna · Harpacticoids · Nematodes · Ostracods · Benthic microalgae · Spartina

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Published in MEPS Vol. 240 (2002) on September 12
Print ISSN: 0171-8630; Online ISSN: 1616-1599. Copyright © Inter-Research, Oldendorf/Luhe, 2002