Effects of high pCO2 on Tanner crab reproduction and early life history, Part II: Carryover effects on larvae from oogenesis and embryogenesis are stronger than direct effects

Abstract

Anthropogenic CO2 release is increasing the pCO2 in the atmosphere and oceans and causing a decrease in the pH of the oceans. This decrease in pH, known as ocean acidification, can have substantial negative effects on marine life. In this study, we use wild-brooded larvae and larvae from females held in treatment pH for two brooding cycles over 2 years to detect carryover effects from oogenesis and embryogenesis. Ovigerous females were held at three pHs: ~8.1 (Ambient), 7.8, and 7.5. Exposure to acidified conditions at the larval stage alone had minimal effects on the larvae, possibly because larvae may be adapted to living in an environment with large pH swings. Exposure of Tanner crab larvae to low pH during the embryo phase had a more substantial effect on morphology, size, Ca/Mg content, and metabolic rate than exposure during the larval phase, and maternal exposure during the oogenesis phase increased the carryover effect. Although the larval phase itself is resilient to low pH, carryover effects are likely to have a negative effect on larvae in the wild. These results, combined with negative effects of high pCO2 at other life history stages, indicate that high pCO2 may have a negative effect on the Tanner crab populations and fisheries soon.