Meeting Abstract
Freshwater mussels are some of the most imperiled species in North America and are particularly susceptible to environmental changes due to their sedentary nature. One environmental disturbance that mussels in the Midwest may encounter is an increase in the partial pressure of CO2 (pCO2) that is being explored as a management strategy for the movement of Asian carp. The present study examined the impact of acute (6 h) and chronic (up to 32 d) exposure of elevated pCO2 levels on the mRNA abundance of genes associated with shell growth (chitin synthase; CS) and the stress response (heat shock protein 70; HSP70) in Fusconaia flava. Although mussels initially exhibited an increase in CS following exposure to elevated pCO2 levels for 6 h, long-term exposure resulted in a decrease in CS mRNA abundance, suggesting that mussels may invest less in shell growth during chronic exposure to elevated pCO2 levels. In response to an acute elevation in pCO2 levels, mussels increased the mRNA abundance of HSP70 in mantle and adductor muscle. A similar increase in HSP70 transcript levels was observed in the gill and adductor muscle of mussels exposed to chronically elevated levels of pCO2. This overall increase in HSP70 mRNA levels in F. flava suggests that both acute and chronic exposure to elevated pCO2 levels initiates activation of the stress response. Together, these results suggest that freshwater mussels respond to elevated pCO2 levels by increasing the machinery necessary to ‘deal with’ the stressor and over the long-term, mussels may reduce their investment in processes such as shell growth. Further experiments are underway to assess the capacity of freshwater mussels to recover from exposure to elevated pCO2 once the stressor has been removed.
