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Mechanisms of uptake of radioactive labels by meiobenthic copepods during grazing experiments

1990; Inter-Research; Volume: 68; Linguagem: Inglês

10.3354/meps068071

1616-1599

KR Carman,

Isotope Analysis in Ecology

Use of labeled substrates as a tool for trophic studies in natural marine sediments was examined employing a variety of approaches.The temporal patterns of microbial incorporation of [14C]acetate and parallel uptake of 14C from [14c]-acetate by benthic copepods was not consistent with the patterns expected if copepods took up 14C primarily due to grazing on labeled microbes.Further, in clasping pairs of Zausodes arenicolus, males (which do not feed while clasping) took up more label from [14C]-acetate than did females (which continue to feed while clasped).In contrast, when [14C]bicarbonate was used as a tracer, ca 80 % of the radioactivity was associated with females from clasping pairs of Z. arenicolus.The locations of radioactivity associated with copepods was determined with autoradiographs on copepod sections.Radioactivity from [14c]-acetate was associated only with the cuticle of copepods, and concentrated in areas where epicuticular bacteria associated with the copepods tended to be most abundant.In contrast, radioactivity from [14C]-bicarbonate was concentrated in the guts of copepods.Considered collectively, these observations indicate that uptake of label from [14C]acetate by copepods was not the result of grazing on labeled sedimentary bacteria.Uptake of radioactivity from [14C]-bicarbonate by copepods, however, was almost exclusively due to grazing on labeled photoautotrophs.