The Physiological Response of Non-Target Species, Unionidae Mussels, to CO2 Barriers

The movement and spread of invasive fish species is a topic of recent concern. Owing to their nonphysical nature, gas barriers such as CO₂ are gaining popularity. Research surrounding these barriers has primarily been aimed at their ability to deter fish; little to no research has investigated potential consequences for non-target species that will equally be exposed to these barriers, such as mussels. Freshwater mussels are one of the most imperiled animals worldwide, and have some of their highest diversity in North America. The goal of the current study was to quantify the impacts of short-term exposure to elevated CO₂ and subsequent recovery in a representative freshwater mussel, Fusconaia flava. Hemolymph Cl^-, Mg²⁺, and Na⁺ levels significantly decreased with 6 h CO₂ treatment and did not recover by 6 h post-treatment. The ratio of RNA:DNA was significantly elevated in mussels exposed to short-term barrier level CO₂, and decreased below control levels during recovery. The results of this study suggest that F. flava mussels experienced significant physiological disturbance following short-term CO₂ exposure. Further studies are underway to better understand the long-term impacts of this disturbance on F. flava, including responses to fluctuating exposure to and long-term recovery from barrier level CO₂.