Meeting Abstract
The fitness benefits associated with parental care must be weighed against the potential costs. For example, male sunfish excavate and defend nests in which they care for eggs and newly hatched offspring, increasing their prospects of survival. The associated costs for males may however be substantial, as nesting requires a high level of physical activity and feeding opportunities are potentially limited. This may increase male mortality. Although the nesting energetic costs are assumed to be high, their magnitude is not well quantified. We have used underwater video camera arrays placed adjacent to nest sites to quantify male nesting behavior and estimate its energetic cost. Behavioral categories were identified, and time budgets established. Commonly exhibited behaviors included station holding at the nest, brief nest departures to confront potential predators, and nest fanning. Fanning may be particularly costly as it requires transfer of momentum to the water to create currents that oxygenate the eggs and remove debris while also producing counter thrust to maintain position on the nest. Fanning and station holding dominated overall time budgets, with a potential reduction in fanning behavior through the course of nesting. Video sequences were also used to quantify fish trajectories and fin beat frequencies. These data were combined with laboratory measures of swimming kinematics and metabolic rate to derive cost range estimates for each behavioral category. This indicates an average metabolic cost for nesting of approximately 20 to 40% of the sustainable aerobic maximum, a substantial cost to maintain through a multi-day nesting period.
