Meeting Abstract
When temperatures surpass a certain upper threshold, performance capacities drop sharply, and will ultimately be fatal if high temperatures persist. However, in aquatic environments, organisms face the additional challenge of plummeting oxygen levels with increasing temperatures. In these instances, is temperature really the limiting factor for performance? Or does reduced oxygen availability also play an independent role? To explore these ideas, we collected mosquito fish (Gambusia holbrooki) from three thermal environments; hot (38-42 C), sub-tropical (15-35 C), and cool temperate regions (5-30 C) . After acclimating all fish to normal oxygen at 22 C for 8 weeks, we measured three performance traits (burst speed, general activity, and mating success of males) during acute exposure to four different environmental treatments; 20 C normal oxygen, 30 C normal oxygen, 36 C normal oxygen, and 36 C high oxygen. We predicted that fish would perform best at temperatures that best represented their capture environmental temperatures. Additionally, we predicted that fish at 36 C with high oxygen exposure would exhibit a partial, if not full, increase in performance with the added oxygen. Thus, the amount of increased performance due to added oxygen will shed some light on how limiting oxygen, rather than temperature, is on performance measures of aquatic organisms.
