Limited feeding on bacteria by two intertidal benthic copepod species as revealed by trophic biomarkers
Cnudde, C.; Moens, T.; Hoste, B.; Willems, A.; De Troch, M. (2013). Limited feeding on bacteria by two intertidal benthic copepod species as revealed by trophic biomarkers, in: Cnudde, C. Trophic ecology of intertidal harpacticoid copepods, with emphasis on their interactions with bacteria = Trofische ecologie van intertidale harpacticoide copepoden, met de nadruk op hun interacties met bacteriën. pp. 91-105
In: Cnudde, C. (2013). Trophic ecology of intertidal harpacticoid copepods, with emphasis on their interactions with bacteria = Trofische ecologie van intertidale harpacticoide copepoden, met de nadruk op hun interacties met bacteriën. PhD Thesis. Ghent University (UGent): Gent. ISBN 9789090278285. 209 pp., more
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| Keywords |
Acids > Organic compounds > Organic acids > Fatty acids
Feeding > Artificial feeding > Selective feeding
Isotopes > Stable isotopes
Microbe
Harpacticoida [WoRMS]
Marine/Coastal |
| Author keywords |
Bacterial grazing; Harpacticoid copepods; Nutritional quality; Higher organism interactions |
| Abstract |
Harpacticoids can discriminate between biofilms of different bacterial strains. We investigated whether assimilation of bacteria is selective and whether harpacticoids select the most nutritional bacteria. We specifically focused on the role of bacterial characteristics in copepod food selection. Trophic biomarkers (stable isotopes, fatty acids) were used to test selective assimilation of three bacteria by the harpacticoids Platychelipus littoralis and Delavalia palustris, all isolated from a salt marsh. The bacteria Gramella sp., Jannaschia sp. and Photobacterium sp. with contrasting ribosomal protein and fatty acid contents, were 13C-labelled and offered in a food-patch choice experiment with monospecific and combination (respectively single and two strains per microcosm) treatments.Low assimilation of bacterial carbon and lack of significant FA transfer proved that bacteria were a poor food source for the harpacticoids. Assimilation was copepod species-specific and bacteria strain-specific (preference for Photobacterium). However, only a low degree of selective feeding occurred; it can partly be explained by extracellular metabolites rather than by biochemical content and densities. Finally, the energetic cost of differential bacterivory resulted in a negative fatty acid balance for Platychelipus, while Delavalia showed an improved fatty acid profile and thus a positive response to the low-quality bacterial food. |
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