Heavy metals in the blueband hermit crab, Pagurus samuelis (Stimpson, 1857) (Decapoda: Anomura: Paguridae), from two Southern California habitats

Although heavy metal concentrations naturally vary in the environment, anthropogenic sources of heavy metals can mask and override such fluctuations. Indicator species can be used to determine environmental concentrations of certain metals and evaluate the impacts of metals from associated anthropogenic sources. We sought to determine if the hermit crab Pagurus samuelis (Stimpson, 1857) may play a role as an indicator species along the Southern California coast. Seawater and P. samuelis samples were collected from both Cabrillo Beach and White Point Beach rocky intertidal locations and analyzed for concentrations of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) using microwave plasma-atomic emission spectrometry (MP-AES). Lead concentrations were higher in seawater at Cabrillo Beach compared to White Point Beach, whereas Zn concentrations were higher at White Point Beach than at Cabrillo Beach. All other metals were not significantly different between these locations. Cd was higher in hermit crabs collected from Cabrillo Beach than those from White Point Beach, whereas Cr was higher in crabs collected from White Point Beach compared with those from Cabrillo Beach. In comparisons of seawater with samples of hermit crabs, seawater had higher concentrations of Zn and Cd, whereas hermit crabs had higher concentrations of Cu at both locations, and higher levels of Cr at White Point Beach. While this study does not provide conclusive evidence that P. samuelis is an indicator species, it does demonstrate differences in metal concentrations between tested locations and populations of P. samuelis. Although P. samuelis may not be negatively impacted by the heavy metal concentrations we found, the risks of potential bioaccumulation at higher trophic levels is of concern.