Uncovering adaptive versus acclimatized alterations in standard metabolic rate in brown bullhead (Ameiurus nebulosus)

Abstract

Standard metabolic rates (SMR) were measured in brown bullheads (Ameiurus nebulosus) collected from two locations of the Detroit River, North America, representative of highly contaminated and uncontaminated areas. Measurements of SMR were completed within 10 days of fish collections (acute trials), for fish held in a common pond environment for 1 year (clearance trials) and for F1 generation fish raised in the pond environment (F1 study). SMRs were significantly higher (26%) in fish from the contaminated area during acute trials. Both populations showed large decreases in SMR (49% to 52%) following clearance; however, differences between populations were still evident. There were no significant differences in SMRs between populations for F1 fish. This study demonstrates that Detroit River brown bullheads from contaminated areas have higher metabolic rates than fish from clean locations, and this metabolic effect is retained for long durations after fish are placed in a common environment. The loss of metabolic differences in F1 offspring indicates that the observed differences in SMR were acclimation-based and not adaptive or related to maternal effects.