Abstract

Forty common murres (Uria aalge) were captured in Monterey Bay, CA over six nights for a dispersant exposure study. All birds were in good to excellent body condition and appeared healthy at the time of capture. On day 7, a veterinary ophthalmologist examined 31 birds using phenol red thread tests (PRTT), fluorescein staining, slit lamp biomicroscopy, and rebound tonometry. Twelve of 31 birds had corneal ulcers, some of which had evidence of chronicity. Ten of 31 birds had mild to moderate conjunctivitis which was bilateral in 80% of the cases. On day 8, birds were divided into seven treatment groups and a control group and underwent a 90 sec exposure to artificial seawater with either Prudhoe Bay Crude Oil, COREXIT 9500 dispersant, or a mixture of the two. On day 10, birds were reevaluated. Post-exposure tear production decreased in all birds, although not significantly. Intraocular pressure was unchanged. Six birds developed corneal ulcers after exposure. Eleven birds developed conjunctivitis. Birds exposed to oil were 11.3 times more likely to develop conjunctivitis than birds not exposed to oil (odds ratio, p=0.0495). Birds exposed to dispersant were 15 times more likely to develop conjunctivitis (odds ratio, p=0.0347). Due to the high prevalence of ocular lesions, these birds should have ophthalmic exams when presented for rehabilitation. Exposure to dispersant in artificial seawater resulted in conjunctivitis in many birds, indicating that dispersants are not innocuous. The use of dispersants in oil spill response should take into consideration the potential for adverse effects on seabirds.