| Summary: | Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, Spain We investigated the direct effects of CO2-induced changes in seawater pH (i.e. control: 8.17 vs. low: 7.75 in NBS-scale) on the feeding, fecundity, hatching success and respiration of two marine copepods: the calanoid Acartia grani and the cyclopoid Oithona davisae. Indirect effects, mediated by potential CO2-induced changes in the nutritional characteristics of their prey, were additionally investigated on A. grani fed on the autotrophic dinoflagellate Heterocapsa sp., cultured at three distinct pH levels (control: 8.17, medium: 7.96, low: 7.75 in NBS-scale). Water acidification had no direct effect on the examined vital rates for any of the two copepod species. Feeding and reproduction of A. grani were also similar among pH treatments when indirect effects were tested, in accordance with the lack of difference in the cellular stoichiometry and fatty acid composition observed among the three offered Heterocapsa diets. Our results lend support to the generally observed lack of direct influence of the seawater pH decrease projected at the end of the century on the group of copepods, while they disagree with other studies that have revealed an indirect “bottom-up” effect Peer Reviewed
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