Free-ranging marine birds are severely impacted by petroleum released into the environment. Although petroleum can affect many organ systems, oxidative damage to red blood cells (RBC) and development of Heinz body anaemia is the only known mechanism of RBC damage in oil-exposed marine birds. Rhinoceros auklets (Cerrorhinca monocerata) were orally exposed to 0, 2.5 or 10 ml of Prudhoe Bay crude oil/kg body weight for five consecutive days by gavage tube. No statistically significant differences between treatment groups were evident for the following blood parameters: packed cell volume (PCV); haemoglobin concentration (Hb); mean corpuscular haemoglobin concentration (MCHC); reticulocyte percentage; fibrinogen concentration; white blood cell count (WBC); and cell counts of heterophils, lymphocytes, monocytes, eosinophils and basophils. After petroleum exposure, blood samples from auklets did not have any evidence of haemolysis, oxidative RBC damage or Heinz body formation as determined by new methylene blue staining of blood smears. Anaemia developed in both oil-exposed and unexposed auklets within 3 weeks of being captured and placed in captivity. Anaemia persisted throughout the duration of the study (77 days). Statistically significant differences over time were identified for PCV, Hb concentration, MCHC, reticulocyte percentage, fibrinogen concentration and lymphocyte, eosinophil and basophil numbers in auklets, without regard to petroleum exposure status. A mild transient regenerative response was noted after gavaging birds with either petroleum or sterile saline, however, the PCV never returned to levels measured immediately after capture. It is likely that anaemia associated with petroleum exposure in seabirds is multifactorial and may be associated with the sedentary nature of captivity, a variety of captivity associated stressors and possibly, the age of affected birds. Furthermore, neither inflammatory nor acute phase responses were consistent indicators of petroleum ingestion.
- Petroleum toxicity
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