Freshwater mussels are among the most rapidly declining and imperiled taxa globally, facing numerous anthropogenic-induced stressors. In a changing landscape, it is essential to understand the response of mussel food webs and health indicators to environmental change at the watershed and stream scale. In this study, we applied stable isotopes to investigate how the diet and fatty acid content of four bivalve species responded to watershed land cover and water chemistry in rivers of Indiana, USA. We sampled three species of native mussel and invasive clam Corbicula fluminea from 10 rivers along a gradient of environmental conditions. To evaluate diet, we employed mixing models using common food sources (e.g., residue from row crop agricultural, riparian trees, riverine detritus, and biofilm) as end members. We incorporated fatty acid analysis to link resource use and nutrition to bivalve health and physiology. We found strong differences in stable isotope and fatty acid profiles across sites and between native and non-native bivalves. Across sites and species, we found high variation in essential polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid, arachidonic acid, and alpha-linolenic acid. Select PUFAs and trophic position (δ¹³C and δ¹⁵N) interacted with increasing watershed cultivated and developed land cover. These preliminary findings highlight important interactions between environmental change, trophic dynamics, and the health of bivalve communities facing significant biodiversity loss. Mixing models will provide novel insights by quantifying the contributions of various food sources to the diets of native and non-native bivalves across environmental gradients. Using this approach, we will assess how changes to land use, nutrient concentrations, and habitat conditions alter the relative importance of autochthonous and allochthonous resources. This analysis enhances understanding of the factors driving freshwater mussel diet and health informing conservation efforts to refine management strategies for these vital yet vulnerable organisms.