Linking a seasonal freshwater prey subsidy to the body condition of an estuarine consumer in a subtropical coastal river

Movements of fishes among habitats often correspond to shifting resource availability and can occur in response to fluctuating freshwater inflows in coastal systems. Seasonal availability of prey can provide resources that increase fitness, yet hydrologic variability can influence the movements of both consumers and prey. Shifts in the timing/magnitude of prey availability driven by climate and water management may lead to a resource mismatch, carrying consequences for growth, survival, and reproduction. Here, we examined how seasonal/interannual variation in prey biomass (sunfishes, Lepomis spp.) affects the body condition of Common Snook (Centropomus undecimalis) in Everglades National Park. Further, we investigated how condition relates to hydrologic variation (water level, temperature, and the duration of marsh drydown). Using GLMMs, we modeled snook condition in relation to sunfish biomass, hydrologic conditions, and fish size. Our results indicate that snook body condition was best explained by a combination of factors, increasing with higher sunfish biomass, lower water levels, during the transition between wet/dry seasons, and with fish size. Population health is not typically included as a management endpoint in monitoring efforts, although quantifying condition is straightforward and cost effective. We highlight that incorporating bioindicators for multiple species into monitoring and assessment could aid in evaluating the efficacy of water management and restoration efforts.