Oxidative ecology of paternal care in wild smallmouth bass, Micropterus dolomieu

Physiologically, oxidative stress is considered a homeostatic imbalance between reactive oxygen species production and absorption. From an ecological perspective, oxidative stress may serve as an important constraint to life history traits such as lifespan, reproduction, and the immune system, and is gaining interest as a potential mechanism underlying life history trade-offs. Of late, there has been much interest in understanding the role of oxidative stress in the ecology of wild animals, particularly during challenging periods such as reproduction. Here, we used a long-term study population of a fish with sole-male parental care, the smallmouth bass, Micropterus dolomieu, to examine the associations among oxidative stress indicators and life history variables in nest-guarding males. In addition, we investigated the potential role of oxidative stress as a physiological mediator of the life history trade-off decision of paternal smallmouth bass to stay with or abandon their brood. We found that oxidative stress was significantly related to the life history of paternal smallmouth bass, such that older, larger fish with greater reproductive experience and larger broods nesting in cooler water temperatures had lower levels of oxidative stress. However, we found no significant correlation between oxidative stress and nesting success, suggesting that oxidative stress may not be involved in the decision of male smallmouth bass to abandon their brood. Wild fish have been relatively understudied in the emerging field of oxidative ecology, and the study presented here makes noteworthy contributions by revealing interesting connections between the life histories of paternal smallmouth bass and their oxidative status.