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Mussels that were collected for glycogen analysis were immediately placed on ice to preserve the tissue for later analysis (following Dunn and Ellis, 2005). In the lab, individuals were sexed via external shell morphology, dried in a drying oven to a constant mass, weighed, then approximately 10mg of foot tissue was collected and run for glycogen analysis (following Naimo et al. 1998). For mussels that were sampled for metabolomics analysis, in the field, immediately after collection, approximately 200uL of hemolymph was drawn from the anterior adductor muscle using a 27–29-gauge syringe, stored in a 2mL cryotube, and flash frozen in liquid nitrogen. Unionids were then scraped of all zebra mussels if present and returned to the benthos. All zebra mussels greater than length 5mm were counted and measured along the major axis of the shell. Cumulative dry weight of all zebra mussels was estimated using a standard conversion of length to dry weight for zebra mussels (Coughlan et al. 2021). Zebra mussel loads were calculated as total estimated zebra mussel dry mass divided by the total dry mass of the unionid soft tissue. Hemolymph samples were stored at -80˚C until they were shipped on dry ice to West Coast Metabolomics Center at UC-Davis for non-targeted analysis of primary metabolites. Metabolites were identified using gas chromatography time-of-flight mass spectroscopy (GC-TOF MS and their peak heights were normalized to the sum peak height of annotated compounds (mTIC-normalization) by the West Coast Metabolomics Center. Each metabolite was independently normalized to zero and standardized to one standard deviation.