Essential metals, whether naturally occurring or introduced, support biofilm nutrient acquisition but can also be toxic or disrupt these functions at elevated concentrations. Despite the role of essential metals (e.g. Fe, Zn, Mo) in mediating biofilm growth and nutrient processing, their potential influence on macronutrient stoichiometry is still underexplored. This study investigates biofilm stoichiometry (C:N) in streams along a human land-use gradient and attempts to connect variation in biofilm stoichiometry to metal availability. Biofilms and surface waters were sampled from 52 streams within urban, mixed, and forested watersheds in the Akron-Greater Cleveland metropolitan area of Ohio. Nutrients and metals were measured in biofilms, and stoichiometric ratios were compared to measures of water chemistry. Urban streams had higher concentrations of many essential metals (Al, As, B, Co, Mo, Ni, V, Zn, and Ca) than forested streams. However, Fe and Mn concentrations were similar in both mixed and urban reaches. C:N ratios varied significantly with land use with the lowest C:N in urban streams while mixed and forested streams had higher C:N. In the urban watersheds, greater concentrations of 6/14 available metals (Fe, Al, Co, As, Ni, V) were associated with higher C:N, and 4 metals (Mo, Mn, Ca and B) associated with lower C:N, with similar relationships in mixed watersheds. In forested streams, only 4/14 metals had greater concentrations associated with high C:N with concentrations of most metals (9/14) exhibiting a negative correlation with C:N ratio. For metals most important for N acquisition, Mn and Mo, rather than Fe, showed the strongest relationship with variation in C:N. These results suggest that environmental metals may influence biofilm stoichiometry. Ongoing analyses of surface water macronutrient (N, P) and water chemistry data from the study aim to better understand these relationships.