Meeting Abstract
Ectothermic species are affected by environmental fluctuations, and studies are needed on thermal tolerances since changes in ambient temperature affect metabolic demands. Zebra mussels are highly invasive, yet little is known about their physiology under biologically relevant conditions, especially with regard to cellular parameters. This study utilized AMP-activated protein kinase (AMPK), a key regulator of cellular energy levels, to examine the effects of cold water temperatures on zebra mussel (Dreissena polymorpha) physiology. AMPK activity reflects changes in energy supply and demand, which are typically associated with high temperature stress. However, a previous study showed that cold acclimation resulted in a temporary elevation in AMPK activity in zebra mussels. In order to investigate this response further, zebra mussels were collected, exposed to a rapid and progressive temperature decrease to 10°C, and held at 10°C for 24 hours. AMPK activity did not increase above baseline levels during the progressive temperature decrease. However, by 24hrs, there was a significant elevation in AMPK activity. One possible explanation is that the processes associated with acclimation to cooler waters may be energetically taxing. In other species, the process of thermal acclimation involves changes in biochemical reaction rates and gene expression. Therefore, it is reasonable to assume that this process would temporarily increase metabolic demands. Zebra mussels are capable of thermal acclimation, and as ambient water temperature varies, the sublethal and lethal temperature ranges also vary. In addition, a two-week lab acclimation to winter conditions is sufficient to alter the thermal tolerances of summer collected mussels, suggesting that thermal acclimation can occur quickly and that water temperature is the main driver of this process.
