Aerobic and anaerobic metabolism of juvenile red drum, Sciaenops ocellatus, is not compromised at summer temperatures

Juvenile red drum (Sciaenops ocellatus) reside in estuaries where they are commonly exposed to warm temperatures during the summer. The characteristics of their overall metabolism when they are active and growing at warmer temperatures have not been well-studied. Here we investigate juvenile red drum aerobic and anaerobic metabolism at a range of ecologically relevant summer temperatures (24ºC, 27ºC, 30ºC, and 33ºC) and test two hypotheses: 1) aerobic scope (the difference between routine and maximum metabolism) increases with temperature, and 2) anaerobic metabolism supports exhaustive exercise in greater than predicted amounts. Routine metabolic rate increased significantly from 13.5 ± 0.67 S.E.M. mmol O2 kg−1h−1 at 24ºC to 17.5 ± 0.89 at 33ºC. Maximum metabolic rate increased from 41.8 ± 1.33 at 24ºC to 56.0 ± 2.82 at 27ºC but did not change between 27ºC and 33ºC. Aerobic scope increased significantly from 28.4 ± 1.19 at 24ºC to 40.0 ± 2.73 at 27ºC and remained high from 27ºC to 33ºC. Routine tissue lactate (6.37 ± 0.45 mmol g−1) and maximum tissue lactate (79.6 ± 2.17 mmol g−1) did not change with temperature. The percent anaerobic contribution to energy expenditure did not differ across temperatures and was 35% ± 1.9. Overall, the highest temperature tested (33ºC) was not detrimental to juvenile red drum metabolism, suggesting this species is metabolically equipped to tolerate warm water temperatures. However, additional factors such as hypoxia or pH should be explored for a better understanding of how juvenile red drum tolerate warm summer seasons and expected future conditions.