Meeting Abstract

9-2  Thursday, Jan. 4 08:15 – 08:30  Differential Temperature Sensitivity of Oxygen Uptake in Hypoxia in Marine Fishes SOMO, DA*; MORRISON, PR; RICHARDS, JG; The University of British Columbia; The University of British Columbia; The University of British Columbia somo@zoology.ubc.ca

Temperature increases and hypoxia are two key factors associated with global climate change already affecting the distribution and abundance of marine organisms. In an effort to predict climate-changed induced shifts in habitat suitability, models have been developed based on the temperature sensitivity of the critical oxygen tension (P_crit) for minimum rate of oxygen uptake (Ṁo_2min). Few studies have used a robust comparative approach to understand the physiological significance of variability in the temperature sensitivity of P_crit. We measured the impacts of acute temperature increase on P_crit in nine species of marine sculpin which vary in hypoxia tolerance to characterize the intrinsic temperature sensitivity of this trait. We also measured critical thermal maximum (CT_max) to assess relationships between P_crit and CT_max. Though P_crit and Ṁo_2min increased significantly with temperature in all species, sculpins fall into two groups: those with nearly equal Q₁₀ values for these two traits, and those with significantly lower Q₁₀ values for P_critvs. Ṁo_2min. The Q₁₀ analysis suggests that some sculpins acutely increase their capacity for oxygen uptake in hypoxia at higher temperatures despite large increases in Ṁo_2min. Preliminary measurements suggest that the temperature sensitivities of hemoglobin-O₂ binding affinity are similar to temperature sensitivities of P_crit, potentially implicating a role for differential temperature effects on hemoglobin-O₂ binding in modulating whole-animal oxygen uptake in hypoxia at elevated temperature.