Meeting Abstract
Given that invertebrates can be commercially important, indicators of ecosystem health and climate change, or invasive, their physiology is of interest. As conformers, invertebrates experience physiological changes as temperature and dissolved oxygen (DO) levels, vary. Increased water temperatures due to climate change and decreased DO levels due to nutrient runoff are altering these habitats. Even though stressors often co-occur, few studies have investigated their combined effect. The invasive zebra mussel was used as a model species for examining the effects of heat and hypoxia, alone, and in combination. Mussels were collected in central IL and exposed to heat, hypoxia, both, or neither for 6 hours. Three cellular stress markers were evaluated: heat shock protein 70 (HSP70) as an indicator of protein denaturation, phosphorylated AMP-activated protein kinase (active AMPK) as a measure of metabolic balance, and total AMPK levels as a measure of the pool of available molecules. Results show active AMPK levels increased over time but then returned to baseline levels with extended exposure to either heat or hypoxia alone. However, active AMPK increased and remained elevated over time when these stressors co-occurred. Total AMPK and HSP70 levels increased over time in response to either heat and hypoxia, but remained at baseline levels in response to heat and hypoxia in combination. One possible explanation is that the cumulative effects of heat and hypoxia are too energetically taxing for protein synthesis. If so, increased levels of active AMPK could be explained by phosphorylation from within an existing pool of molecules. Therefore, these results suggest that there is a synergistic effect, where exposure to both heat and hypoxia is more stressful that the effect of either in isolation.
