Seawater carbonate chemistry and life history traits and feeding of the littoral mysid Praunus flexuosus

Mysids, an important food web component in the littoral zone of coastal waters, have been neglected so far in ocean acidification research. Juveniles of the littoral mysid Praunus flexuosus were exposed in the laboratory to four pCO2 levels (530, 930, 1200, and 1600 µatm) for 5 weeks. In addition, juveniles were provided with two different food levels during the experiment. High pCO2 did not affect survival, but delayed moulting. Juvenile growth decreased and inter-moult period between the last moulting events increased with increasing pCO2 at low but not at high food supply, suggesting that high food availability is needed to prevent these negative effects of elevated pCO2. However, small individual juveniles showed lower feeding rates at high pCO2 compared to the control after prolonged exposure, suggesting decreased activity likely due to impaired metabolism. The subtle negative effects of elevated pCO2 on life history traits observed in this study suggest that P. flexuosus probably has to adapt to counteract adverse effects of predicted high pCO2, especially when food is limiting.