Effects of Ocean Acidification on Eggs and Larvae of a North Pacific Flatfish

The potential responses of commercial fishery species to ongoing ocean acidification has yet to be broadly explored. In this study we examined the responses of egg and larval northern rock sole (Lepidopsetta polyxystra) to elevated CO₂ levels (to 1500 µatm). Larvae from four females differed significantly in size-at-hatch, but there was no significant effect of CO₂ level on size or survival to hatch. In three separate larval trials, there was little effect of CO₂ level on growth through the first 28 days after hatch. However, across larval rearing trials there was a trend toward higher mortality rates in treatments with elevated CO₂ levels and in one trial, extended to 60 dph, lower condition factors observed after 28 dph among fish at high CO₂ levels suggesting that later stage larvae undergoing metamorphosis may be more sensitive to environmental hypercapnia than earlier pre-flexion stages. These results provide an interesting contrast to observations on other flatfish species and suggest that northern rock sole may be more sensitive to ocean acidification than a previously studies of a gadid with the same geographic range. Ongoing work will evaluate the potential effect of nutritional status on sensitivity to elevated CO₂ in pre-flexion and post-flexion larvae.