Midwest Fish & Wildlife Conference 2016

AUTHORS: Diane Waller*, U.S. Geological Survey – Upper Midwest Environmental Sciences Center, Michelle Bartsch, U.S. Geological Survey – Upper Midwest Environmental Sciences Center, Kim Fredricks, U.S. Geological Survey – Upper Midwest Environmental Sciences Center, Craig Jackson, U.S. Geological Survey – Upper Midwest Environmental Sciences Center, Jon Amberg, U.S. Geological Survey – Upper Midwest Environmental Sciences Center

ABSTRACT: Carbon dioxide is being evaluated as a potential deterrent to the range expansion of Asian carp (bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix). Threatened and endangered species of native unionid mussels inhabit areas that have been targeted for CO2 testing and deployment, necessitating a risk assessment of the technology to the fauna. In conjunction with pond and field studies on target fish species, we evaluated the effects of elevated CO2 on juvenile mussels of two species, the fat mucket (Lampsilis siliquoidea) and the federally endangered Higgins eye (L. higginsii). Recent work has indicated that Asian carp species show avoidance behavior when CO2 concentrations approached 70 mg/L. Therefore, juvenile mussels were exposed to a predicted range of CO2 concentrations (30 to 120 mg/L) for 28 days, followed by a 14-d post-exposure period in clean water. The effects of elevated CO2 on mussel survival, growth, behavior, and expression of several target genes (Calmodulin, Na+/K+ ATPase, CO1, and Chitin Synthase) were evaluated. Both mussel species had significantly lower survival in treatments near 70 mg/L CO2, with Higgins eye juveniles (LC50 = 77.7 mg/L) showing greater sensitivity than fat mucket juveniles (88.7 mg/L). Preliminary data also indicated a treatment effect on several sublethal measures, with some degree of recovery after the post-exposure period in clean water. Results will be discussed along with the implications for CO2 barrier deployment and future research needs.