CO2-induced low pH in an eastern oyster (Crassostrea virginica) hatchery positively affects reproductive development and larval survival but negatively affects larval shape and size, with no intergenerational linkages

In North America, studies regarding effects of CO2-induced low pH in bivalve aquaculture are largely restricted to the US Pacific coast Studies on species from the northwest Atlantic are lacking. Furthermore, information on the roles of intergenerational exposure and biological sex in bivalve responses to low pH, particularly in an aquaculture-specific context, is scant. We tested if short-term (1 month) exposure to CO2-induced reductions in pH(NBS) affected the reproductive development of male and female eastern oysters (Crassostrea virginica) during hatchery-specific reproductive conditioning and whether maternal and/or paternal exposure influenced larval responses. Reduced pH (7.5-7.7) increased the rate of reproductive development in both males and females. There was no indication of intergenerational effects; adult pH conditions did not affect early larval development. In contrast, low pH conditions experienced by gametes during spawning, fertilization, and embryo incubation (48 h) resulted in higher larval survival (+6-8% from control), reduced shell height (-2 to 3 mu m), and increased deformities (abnormal shell shape; +3-5%). We suggest that local adaptation to acidic land runoff may account for the positive effects of low pH observed in this study. Bioeconomic assessments are now needed to understand the implications of reduced pH on aquaculture operations in these regions of Atlantic Canada.

Automated summary

Studies in North America on the effects of CO2-induced low pH in bivalve aquaculture are mainly focused on the US Pacific coast, with limited research on species from the northwest Atlantic. Exposure to reduced pH was found to increase the rate of reproductive development in both male and female eastern oysters, but also led to higher larval survival, reduced shell height, and increased deformities during spawning, fertilization, and embryo incubation. Further research is needed to assess the bioeconomic implications of reduced pH on aquaculture operations in Atlantic Canada.