Meeting Abstract
The golden shiner, Notimigonus crysoleucas, is a common bait minnow that often experiences hypoxia events within its freshwater habitat, and also encounters many microhabitats of varying temperatures. In this experiment, golden shiners were exposed to severe hypoxia (1.75±0.12 kPa) for 1 h at two environmentally-relevant temperatures (14 and 24°C), and then allowed to recover for 7 h at 24°C. Standard and maximal metabolic rates and blood plasma parameters were assessed before hypoxic exposure, immediately following exposure, and post-recovery. We hypothesized that cold temperature in combination with severe hypoxia may create a protective effect with respect to the metabolic response. Standard metabolic rate was significantly decreased during hypoxia in the fish exposed to 14°C, but was not affected at 24°C. Golden shiners exposed to hypoxia at 24°C accumulated a greater oxygen debt than the 14°C treatment, but time required to return to pre-exposure SMR was not significantly affected by exposure temperature. Blood plasma lactate concentrations were significantly elevated in golden shiners immediately following hypoxia at both temperatures, and returned to baseline levels after the 7 h recovery period in both groups. Fish exposed to hypoxia in low temperature displayed significantly lower plasma lactate accumulation immediately following hypoxia exposure than fish exposed at 24°C. Similarly, plasma pH was reduced following hypoxia exposure, but only in the fish held at 24°C during hypoxia exposure. These results indicate that, consistent with other cyprinids, golden shiners demonstrate extensive hypoxia tolerance, which is enhanced by reduced temperature.
