Growth phase of the diatom Skeletonema marinoi influences the metabolic profile of the cells and the selective feeding of the copepod Calanus spp.
Year of Publication
Barofsky A, Simonelli P, Vidouez C, Troedsson C, Nejstgaard JC, Jacobsen HH, Pohnert G
Journal of Plankton Research
Copepod diet, prey selectivity, PCR, Sceletonema, Calanus, mesocosm, Espegrend, Bergen, Norway
Copepods dominate the biomass of marine zooplankton and through their prey selectionthey act as top-down regulators of planktonic communities. We investigatedfeeding preference of copepods in the presence of the diatom Skeletonema marinoi atdifferent time points throughout the development of a bloom and a culture.Quantitative PCR gut content assessment revealed that the food uptake of thecopepod Calanus spp. on mixed diets and on artificially induced mesocosm bloomswas selective. Uptake of S. marinoi was highest during the post-bloom phase in themesocosms even if the abundance of this alga was already low. In laboratory assays,copepods showed a greater preference for S. marinoi in the late stationary phase thanfor cultures of the same strain under exponentially growing culture conditions. Thecopepods thus discriminate between different growth phases of a single algal speciesin both laboratory and field settings. In parallel, we monitored cellular metabolites ofthe diatom using a metabolomic approach. Complex changes in the metabolic profileoccur during development of a culture. Since no obvious effect of nutrient qualityand cell size was involved, we suggest that changes in (info)chemicals within orsurrounding S. marinoi regulate selective feeding by zooplankton.
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