Knowledge of the swimming energetics and thermal ecology of sub-tropical and tropical coastal species is extremely limited, yet this information is critical for understanding animal–environment relationships in the face of climate change. Using the ecologically and economically important sportfish, bonefish (Albula vulpes), we determined the critical swimming speed (Ucrit), metabolic rates (Formula presented.), scope for activity, and cost of transport (COTnet) across a range of temperatures using a swim tunnel. For both critical swimming speed and scope for activity, optimal (Topt) and critical (Tcrit) temperatures were determined. The optimal temperature for Ucrit (96 cm/s) was 28.0 °C and the optimal temperature for scope for activity (7.5 mgO2/min/kg) was 26.7 °C. We also estimated the thermal profile of bonefish in the wild using surgically implanted thermal loggers. Of the 138 implanted fish, eight were recaptured with functional loggers. After 220 days more than 55 % of recaptured tagged fish had expelled their thermal loggers. Thermal profiles revealed that bonefish did not exceed laboratory-determined critical temperatures (i.e., 14.5 °C minima and 37.9 °C maxima) and spent the majority of their time at their critical swimming speed optimal temperature. Nonetheless, fish experienced wide variation in daily temperature—both through time (up to 8 °C diel fluctuation and 14 °C seasonally) and among individuals. Collectively, laboratory and field data suggest that bonefish occupy habitats that approach, but rarely exceed (0.51 % of the time) their Tcrit. Bonefish routinely experienced water temperatures in the field that exceeded their Topt (~54 % of the time). Even minor increases in temperature (e.g., 1 °C) in tidal creeks will lead to greater exceedances of Topt and Tcrit or potentially reduce access of bonefish to essential feeding areas.
- Scope for activity
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science