Ocean acidification and warming impacts the nutritional properties of the predatory whelk, Dicathais orbita

•A predatory marine gastropod was subjected to ocean warming and acidification for 35 days.•Ocean warming and acidification caused a 54% and 45% reduction in the protein content of the gastropod meat, respectively.•Glycogen content in gills was 35% lower in gastropods in seawater at 25 °C than at 22 °C.•Overall, gastropods had less stored energy and lower nutritional value when exposed to ocean climate change.

Ocean warming and acidification have the potential to impact the quality of seafood with flow on effects for future food security and ecosystem stability. Here, we used a 35-day experiment to evaluate how ocean warming and acidification may impact the nutritional qualities and physiological health of Dicathais orbita, a predatory muricid whelk common on the east coast of Australia, and discuss the broader ecological implications. Using an orthogonal experimental design with four treatments (current conditions [~ 23 °C and ~ 380 ppm of pCO2], ocean warming treatment [~ 25 and ~ 380 ppm of pCO2], ocean acidification treatment [CO2 ~ 23 °C and ~ 750 ppm of pCO2], and ocean warming and acidification treatment [CO2, ~ 25 °C and ~ 750 ppm of pCO2]), we showed that changes in moisture and protein content were driven by significant interactions between ocean warming and acidification. Elevated ocean temperature significantly decreased protein in the whelk flesh and resulted in concurrent increases in moisture. Lipid, glycogen, potassium, sulfur, and phosphorus content also decreased under elevated temperature conditions, whereas sodium, boron and copper increased. Furthermore, elevated pCO2 significantly decreased lipid, protein and lead content. Whelks from control conditions had levels of lead in excess of that considered safe for human consumption, although lead uptake appears to be lowered under future ocean conditions and will be site specific. In conclusion, while D. orbita has received research attention as a potential food product with nutritious value, ocean climate change may compromise its nutritional qualities and reduce sustainable harvests in the future. Furthermore, ocean climate change may have deleterious impacts on the longevity and reproductive potential of this important rocky shore predator.