Differences in faecal profiles of porphyrins among river otters exposed to the Exxon Valdez oil spill

River otters (Lutra canadensis) living in marine environments of Prince William Sound, Alaska, exposed to crude oil from the Exxon Valdez spill in March 1989, showed significantly elevated levels of faecal porphyrin over those of otters from non-oiled areas (oiled mean = 48.2, and non-oiled mean = 34.5 nmol g(-1) dry faeces). Profiles of uro-, hepta-, hexa-, penta-, copro-, and protoporphyrin profiles were qualitatively characterized by high-performance liquid chromatography. These findings suggest that river otters may serve as a suitable indicator species in which porphyrin profiles can be used to monitor the effects of marine and freshwater crude oil exposure. Also, this is the first model showing the effects of an oil spill on porphyrins on a free-ranging mammal using a non-lethal methodology. These effects were detectable 1 year after the spill and following a major effort to clean oil from the shorelines of Prince William Sound.