Influence of local-scale abiotic and biotic factors on stress and nutrition in invasive silver carp.
Community structure and dynamics in aquatic ecosystems are influenced by a variety of abiotic and biotic factors including productivity, species composition, and temperature. These factors may also affect local-scale community resilience to nonnative species invasions. We used habitat characteristics, zooplankton concentrations, fish abundances, and species composition and richness data collected by two fish population monitoring programs to define relationships that influence stress and nutrition in invasive silver carp (Hypophthalmichthys molitrix). We collected blood samples and quantified nutritional (alkaline phosphatase, cholesterol, protein, and triglycerides) and stress metrics (cortisol and glucose) from individuals across three distinct time periods. Nutritional patterns in silver carp were explained by temperature and food resources, indicating elevated feeding in warmer months. Patterns in blood-based stress parameters were most strongly driven by environmental characteristics, elevating with high water temperatures and increased turbidity. Nutrient levels and community richness parameters did not influence the stress or condition of silver carp, likely due to the absence of limiting resources or competition for this species. Together, our results provide insights into the factors that may influence the spread and distribution of silver carp, as well as the characteristics of habitats that could be vulnerable to future silver carp invasion.