Meeting Abstract
Dissolved oxygen (DO) concentration is a key factor limiting the aerobic capabilities of fishes, and low DO concentration (hypoxia) associated with eutrophication and pollution is now considered to be one of the greatest threats currently facing fishes. Hypoxia can severely limit fish performance, especially aerobically expensive fitness-related behaviours including swimming and sensory information acquisition. Fishes can lessen oxygen requirements and metabolic demands by altering these behaviours under hypoxia, though the exact mechanisms by which they do so can be difficult to quantify. We use weakly electric fishes as a model system for exploring potential effects of hypoxia on swim performance and sensory information acquisition, as we can non-invasively quantify the electric organ discharges (EODs) they use for active acquisition of sensory information during swimming. To quantify potential effects of hypoxia, we measured critical swim speed and concurrent EOD production under high- and low-DO concentrations in a hypoxia-tolerant African mormyrid, Gnathonemus victoriae, following chronic and acute exposure to hypoxia. Our findings indicate that hypoxia exposure resulted in a significant decline in both swim speed and EOD production in fish without previous acclimation to hypoxia. However, individuals acclimated to chronic hypoxia for eight weeks were characterized by a higher critical swim speed under both hypoxia and normoxia than fish acclimated to normoxia. Our results highlight the effects of hypoxia on aerobic swim performance and sensory information acquisition, and the ability of fish to heighten aerobic performance under stressful conditions through acclimation processes.
