Freshwater mussels are a diverse taxonomic group that can influence nutrient dynamics in rivers through the storage of carbon (C), nitrogen (N), and phosphorus (P) in their soft-tissues and shells. Following mortality, nutrients stored in soft tissues are rapidly released, whereas nutrients in shells are released over months to decades, allowing shells to act as long-term reservoirs of nutrients. Mussel life history strategies reflect trade-offs among processes like growth and structural investment, which generate predictable patterns in shell morphology with opportunistic and periodic species generally producing thinner shells than equilibrium species. Previous studies of shell stoichiometry suggest that shell morphology (e.g., shell thickness, surface area, etc.) and life history strategy, may influence shell nutrient composition and decomposition rates. However, little is known regarding how specific morphological traits, such as shell thickness and surface area, regulate shell decomposition or how rates of nutrient leaching from shell material varies among C, N, and P. We hypothesized that thinner-shelled species and shells with greater surface areas will have faster decomposition rates than thicker-shelled species and shells with lower surface area because they are more vulnerable to mechanical breakdown, with opportunistic and periodic species decomposing faster than equilibrium species. To test this, we deployed course mesh bags containing shells of seven freshwater mussel species with varying life history traits (e.g., shell thickness, surface area) along three sites in the Sipsey River, Alabama, USA that were collected periodically over four years to estimate decomposition rates. As predicted, thicker shells decomposed slower than thinner shells; however, increasing shell surface area tended to result in slower decomposition for some species. Ongoing work aims to evaluate how shell nutrient release changes throughout decomposition and how decomposition rates differ among elements. Understanding how shell traits and decomposition vary among species improves our ability to predict mussel-mediated nutrient provisioning and the long-term influence of mussels shells on ecosystem services in rivers.