title: Response of river otters to experimental exposure of weathered crude oil: fecal porphyrin profiles.
abstract: Profiles of porphyrins were characterized in fecal samples from river otters (Lontra canadensis) experimentally exposed to weathered crude oil to determine effects on heme synthesis. Fifteen male river otters were randomly assigned to three groups of five individuals each representing a control group, a low-dosage group that received 5 mg/kg body mass of oil per day, and a high-dosage group that received 50 mg/kg body mass of oil per day. Mean levels of coproporphyrin III (CoproIII) and protoporphyrin IX (ProtoIX) in fecal samples collected from all experimental river otters were higher throughout the experimental period than levels of CoproIII and ProtoIX in fecal samples collected previously at two field sites. No statistically significant differences in levels of CoproIII and ProtoIX were observed between treatment groups, although a trend of reduction in variability in CoproIII was observed in the low- and high-dose groups. We found no relation between levels of CoproIII and ProtoIX, suggesting that the process of disruption that leads to oxidation of the precursors of porphyrins is probably nonlinear. Our results also indicate that the interaction between oiled induced reduction in hemoglobin levels and induction of CYP1A1 corresponded with significantly lower levels of ProtoIX in the fecal samples, possibly representing high demand for ProtoIX. Therefore, while this experiment does not support the use of porphyrin profiles as an individual biomarker, it does suggest that the latter may be valuable when a weight of evidence is used in an ecotoxicological risk assessment in which the interactions between several biomarkers are explored.
authors.affiliation: Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775-7000, USA.
authors.forename: C
authors.initials: C
authors.lastname: Taylor
authors.forename: M
authors.initials: M
authors.lastname: Ben-David
authors.forename: R T
authors.initials: RT
authors.lastname: Bowyer
authors.forename: L K
authors.initials: LK
authors.lastname: Duffy
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000009:adverse effects*; D005243:Feces / Q000737:chemistry; D008297:Male; D010041:Otters / Q000502:physiology*; D010578:Petroleum / Q000009:adverse effects*; D011166:Porphyrins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D010578:Petroleum; D011166:Porphyrins