The combined effects of elevated pCO₂ and food availability on Tigriopus japonicus Mori larval development, reproduction, and superoxide dismutase activity

Previous studies have shown that ocean acidification has little effect on adult Tigriopus japonicus copepods, and mainly impairs the early development and reproduction of females. This study investigated the possible interactive effect between CO2-induced seawater acidification and food availability on larval development and reproductive output in T. japonicus. Copepods were exposed to either pH 8.1 or pH 7.3 under different food concentrations (0.5 × 10⁴–80.0 × 10⁴ cells/mL). Both the development of nauplii and copepodites was delayed at pH 7.3 with a greater effect at lower food concentrations. The reproductive output followed a bell-shaped curve with the highest reproductive output at food concentrations between 30 × 10⁴ and 40 × 10⁴ cells/mL. As an indicator of oxidative stress, the activity of superoxide dismutase increased at lower pH, with a greater increase at lower food concentrations. Therefore, the effect of elevated pCO₂ on T. japonicus was food dependent.