UC San Diego

Crustaceans are relatively understudied in regards to their vulnerability to the changing ocean conditions of ocean acidification and ocean warming. Although they are generally considered less vulnerable to reduced pH and increased temperature than other calcifying groups, studies have found potential effects on their growth, energy storage, and prey detection. In this study, we examined the vulnerability of the ridgeback prawn, Sicyonia ingentis, which is a commercially important species along the West coast of the United States. Prawn were exposed to reduced pH (7.50 ± 0.02; pCO₂ = 1475 ± 25 µatm) and increased temperature (16.2 ± 0.7°C) conditions in a full factorial design for twelve weeks. Prawns were monitored for survival and growth throughout the experiment. At the end of the experiment, their prey detection was analyzed via antennular flicking rates, and they were dissected for Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) measurements, which are indicators of gonad development, energy storage, and the trade-off between the two. No significant effect of treatment was found for antennular flicking, GSI, or HSI. The second molt increment was significantly less in the reduced pH/increased temperature treatment in comparison to the control (ANOVA: F3,18 = 3.36, p = 0.04), but growth over the experiment did not differ among treatments. Survival was significantly lower in the reduced pH/increased temperature treatment. S. ingentis is robust to a pH below its natural range, but the synergistic effects of reduced pH and increased temperature have a significant impact on mortality.