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

Carman, Kevin R.

doi:10.3354/meps068071

Cited by 33 publications

(16 citation statements)

References 29 publications

(34 reference statements)

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“…One can consider the importance of labeled micro-organisms attached to the body and appendages of the copepods in biasing measurements of true assimilation of labeled carbon. Carman (1990) found that uptake of 14 C-labeled diatoms by copepods was almost entirely due to grazing on labeled microalgae.…”

Section: Discussionmentioning

confidence: 95%

Does sediment grain size affect diatom grazing by harpacticoid copepods?

Troch

Houthoofd

Chepurnov

et al. 2006

Marine Environmental Research

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Estuarine soft sediments support a diverse group of eukaryotic and prokaryotic organisms though the role of the sediment per se for the functioning of these organisms remains largely unknown. The present study aimed to test the eVect of sediment grain size on the grazing activities of harpacticoid copepods. In controlled experiments, two common intertidal harpacticoid species (Paramphiascella fulvofasciata and Nitokra spinipes) were each oVered a mix of two benthic diatom species (Navicula phyllepta and Seminavis robusta) in diVerent sedimentary conditions. Several microcosms were created using a variety of sediment types, including Wne silt (<63 m), coarser grained sands (125-250, 250-450, 100-300 m), artiWcial 'sediments' of glass beads (250-500, 2000 m) and even the absence of sediment was tested. The diatoms were enriched in the stable carbon 13 C to facilitate tracing in the harpacticoids. Both copepod species were able to graze on the diatoms with highest uptake when sediment was absent. In contrast, both harpacticoid species showed no uptake in silty conditions. In general, grazing was favoured when mean sediment grain size increased. The strong negative eVect of Wne grains on the grazer's eYciency can be explained by the resulting diVerences in the structure (and accessibility) of the diatom bioWlm on the one hand and the mobility of the grazer on the other hand. In view of the subtle equilibrium between primary producers and grazers, these results might have important implications for the eVect of siltation of tidal Xats due to, e.g., human activities. 

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Section: Discussionmentioning

confidence: 95%

Does sediment grain size affect diatom grazing by harpacticoid copepods?

Troch

Houthoofd

Chepurnov

et al. 2006

Marine Environmental Research

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“…However, it is the preferred method to introduce label while minimizing sediment disturbance (Dobbs et al 1989). Label uptake by nongrazing processes has been reported by Carman (1990), which may complicate the interpretation of the 13 C data in terms of grazing. However, turnover time of glucose (hours) is much shorter than that of bacteria (days), which allowed a distinction between direct uptake of glucose and bacterial grazing at the time scale of the experiment.…”

Section: Discussionmentioning

confidence: 99%

The fate of bacterial carbon in an intertidal sediment: Modeling an in situ isotope tracer experiment

et al. 2006

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We report the results of an integrated modeling and in situ isotope tracer experiment study examining the fate of bacterial carbon in an intertidal sediment. 13 C-glucose was injected into the upper 10 cm of an intertidal sediment, which successfully tagged the bacterial community as evidenced by 13 C enrichment of bacterial specific polar-lipid-derived fatty acids. Over a period of 4.5 months, 13 C enrichment was monitored in sediment organic carbon, bacteria, meiobenthos, macrobenthos, and dissolved inorganic carbon. A mechanistic model accurately simulated label transfer among the biotic and abiotic compartments and was used to derive bacterial production and the loss processes grazing, mortality, respiration, and exchange. Bacterial production averaged 67 mmol C m 22 d 21 , of which 8% was lost from the sediment by exchange processes, 3% was grazed by meiobenthos and 24% by macrobenthos. The primary fate of bacterial production was mortality (65%) and the released bacterial carbon was recycled back to dissolved organic carbon, resulting in recycling of carbon within the dissolved organic carbon-bacteria loop. Bacterial respiration was the main loss process from this loop. Although a significant fraction of bacterial carbon production was grazed, our results show that bacterial carbon is primarily a sink of organic carbon in the food web of intertidal sediments.

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“…This is a major advantage, since comparably the radiotracer techniques suffer from methodological problems caused by the sorption of tracers to ineiobenthic organisms not related to grazing (see e.g. Montagna & Bauer 1988, Carman 1990) and from possible perturbation of feeding behaviour due to injections into the sediment. A major disadvantage of the HPLC method is the uncertainty regarding the extent and rate of pigment conversion into colourless products in the copepod gut.…”

Section: Discussionmentioning

confidence: 99%

“…However, due to methodological problems (see e.g. Montagna & Bauer 1988, Carman 1990), the preference exerted by copepods on bacteria has probably been overestimated and the feeding behaviour of harpacticoid copepods in their natural environment remains poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Feeding selectivity of the harpacticoid copepod Canuella perplexa in benthic muddy environments demonstrated by HPLC analyses of chlorin and carotenoid pigments

Buffan‐Dubau¹,

Wit²,

Castel³

1996

Mar. Ecol. Prog. Ser.

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The natural diet and the feeding selectivity of the harpacticoid copepod Canuella perplexa T & A Scott, 1893 were studied in submerged muddy sediments of artificial lagoons in Arcachon Bay (SW France) This study focused on the role of phototrophic microorganis~ns as food sources. Therefore, chlorln and carotenoid pigments in copepods were compared with those present In the top 3 cm of the sediment. High performance liquid chromatography with o n -l~n e measurement of absorption spectra was used for separation, identification, and quantification of pigments. Diatoms, purple phototrophic bacteria, cyanobacteria, and green microalgae contributed to the benthic phototrophic community. C perplexa ingested diatoms and infrequently cyanobacteria and/or green microalgae in preference to purple phototrophic bacteria. Ingested chlorophyll was converted into phaeophytln and phaeophorblde-like compounds Moreover the copepod synthesized astaxanthin and a related isomer most likely from lngested p-carotene.

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

Cited by 33 publications

References 29 publications

Does sediment grain size affect diatom grazing by harpacticoid copepods?

Does sediment grain size affect diatom grazing by harpacticoid copepods?

The fate of bacterial carbon in an intertidal sediment: Modeling an in situ isotope tracer experiment

Feeding selectivity of the harpacticoid copepod Canuella perplexa in benthic muddy environments demonstrated by HPLC analyses of chlorin and carotenoid pigments

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