This study describes a novel test for 16 metals using Argiope argentata as indicators of environmental pollution. Our results suggest that A. argentata from a relatively isolated California island suffer a more diverse metal burden than those from the California mainland. Metal burdens of Cd, Cs, Ni, Sr, Tl, and U were greater in Santa Catalina specimens. Only the metal burdens of As and V were greater in the mainland Encinitas specimens. The metal burdens of Be, Bi, Co, Cr, Ga, In, Li, and Pb were not different between the sites. Soil samples taken later from the same sampling locations confirm higher concentrations of Cd, Ni and Sr on Santa Catalina, while cactus plants from the sites had a different pattern of metal accumulation. The effect of metal burden on spider body weight was examined, and Santa Catalina A. argentata had significantly increased mass compared to Encinitas spiders. This indicates that, despite a more diverse burden of metals, A. argentata spiders from Santa Catalina may have a higher fitness than those from Encinitas.