Thermal tolerance and metabolic responses of brushtail tang, zebrasoma scopas

The Brushtail tang (Zebrasoma scopas) is an important herbivorous fish species that plays a vital role in the maintenance of coral reef health though algal grazing. Algal grazing prevents algal overgrowth and thus a shift in reef ecology from dominant coral to pervasive algae. This project aimed to quantify the effects of rising ocean temperatures on the survivorship and metabolic rates of Brushtail tang on the reefs surrounding Hoga Island, Indonesia. Fish were housed at 26° and 30°C for the duration of the experiment, consistent with current and predicted sea surface temperatures over the next century. Stop flow respirometry was used to determine the resting metabolic rate of Brushtail tang at both temperatures, and total oxygen consumption was used as proxy for resting metabolic rates. Metabolic compensation ability was determined using individually derived Q10 values for fish acutely exposed to warmer waters, and measurements were taken over a time series of 1, 3, 7 and 10 days to test the effect of acclimation to warmer waters . The temperature tolerance of brushtail tang was also determined using standard Critical Thermal Maximum Methodology (CTmax) with inversion as non-lethal endpoints. The ability of brushtail tang to metabolically compensate when acutely exposed to warming waters was found to be greater than that of other tropical reef fishes. However acclimation was not found to further increase the metabolic compensation ability of this species. Additionally acute exposure to elevated temperatures did increase the species CTmax, while acclimation was found not to further increase the species CTmax. Such data should prove useful for the prediction of the species responses to rising sea temperatures likely to be encountered over the next century.