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The re-use of faecal pellets in the water column before sinking to the seafloor is known as an important pathway in marine
food webs. Especially planktonic copepods seems to be actively use their faecal pellets. Since benthic copepods (order Harpacticoida)
live in the vicinity of their pellets, it remains unclear how important these pellets are for their feeding ecology. In the
present study a laboratory experiment was conducted to analyse the importance of faecal pellets for the feeding ecology of
the harpacticoid Paramphiascella fulvofasciata and its grazing pressure on two diatom species (Seminavis robusta, Navicula phyllepta). By quantifying the amount and volume of the produced faecel pellets in different treatments, it was tested to what extent
the food source and the lack of faecal pellets would influence the production of faecal pellets. We found that the grazing
pressure of P. fulvofasciata depended on the diatom density since only a top-down effect could be found on the smaller Navicula cells during its initial exponential growth phase. The grazer had a negative effect on the diatom growth and controlled the
cell density to about 4,000 cells/cm2. In spite of the fact that the addition of faecal pellets did not show a significant positive effect on the assimilation
of diatoms, the removal of faecal pellets strongly promoted the pellet production. Especially when grazing on Navicula the harpacticoid P. fulvofasciata produced significantly more and smaller faecal pellets when the pellets were removed. This outcome illustrates the need for
faecal pellets of this harpacticoid copepod when grazing on the diatom Navicula. Apart from its selection for smaller diatom cells, it was suggested that the colonisation of heterotrophic bacteria enriched
these pellets. This study is the first to indicate that trophic upgrading occurs on faecal pellets and not only on the initial
autotrophic food sources per se. 相似文献
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The trophic importance of bacteria to harpacticoid copepods in intertidal areas remains poorly understood, and so do the mechanisms of bacterial feeding. It is, for instance, unclear whether harpacticoids directly target bacterial cells or merely co-ingest them with substrates to which bacterial cells may be attached. Here, we investigate bacterial uptake and substrate requirement for four mud intertidal species (Microarthridion littorale, Platychelipus littoralis, Delavalia palustris and Nannopus palustris) by means of 13C-labeled bacteria and biomarker fatty acids (FA). Bacterial uptake strongly depended on grazing on a primary food source but bacterial ingestion rates were low, and no clear indication of copepods directly targeting bacteria was found. Delavalia was the only species that accumulated bacteria-derived FA and gained in polyunsaturated FA (PUFA) probably through bioconversion of bacteria-derived FA. In general, however, our results suggest that bacteria represent a relatively minor and low-quality food for intertidal harpacticoid copepods. 相似文献
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Devault Damien A. Massat Félix Lambourdière Josie Maridakis Clio Dupuy Laëtitia Péné-Annette Anne Dolique Franck 《Environmental science and pollution research international》2022,29(44):66315-66334
Environmental Science and Pollution Research - Massive Sargassum beachings occurred since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and... 相似文献
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