Changes in white cell estimates and plasma chemistry measurements following oral or external dosing of double-crested cormorants, Phalacocorax auritus , with artificially weathered MC252 oil

Abstract

A B S T R A C TScoping studies were designed whereby double-crested cormorants (Phalacocorax auritus) were dosed with artificially weathered Deepwater Horizon (DWH) oil either daily through oil injected feeder fish, or by application of oil directly to feathers every three days. Preening results in oil ingestion, and may be an effective means of orally dosing birds with toxicant to improve our understanding of the full range of physiological effects of oral oil ingestion on birds. Blood samples collected every 5-6 days were analyzed for a number of clinical endpoints including white blood cell (WBC) estimates and differential cell counts. Plasma biochemical evaluations were performed for changes associated with oil toxicity. Oral dosing and application of oil to feathers resulted in clinical signs and statistically significant changes in a number of biochemical endpoints consistent with petroleum exposure. In orally dosed birds there were statistically significant decreases in aspartate amino transferase (AST) and gamma glutamyl transferase (GGT) activities, calcium, chloride, cholesterol, glucose, and total protein concentrations, and increases in plasma urea, uric acid, and phosphorus concentrations. Plasma electrophoresis endpoints (pre-albumin, albumin, alpha-2 globulin, beta globulin, and gamma globulin concentrations and albumin: globulin ratios) were decreased in orally dosed birds. Birds with external oil had increases in urea, creatinine, uric acid, creatine kinase (CK), glutamate dehydrogenase (GLDH), phosphorus, calcium, chloride, potassium, albumin, alpha-1 globulin and alpha-2 globulin. Decreases were observed in AST, beta globulin and glucose. WBC also differed between treatments; however, this was in part driven by monocytosis present in the externally oiled birds prior to oil treatment.

Organ weights and histopathology of double-crested cormorants ( Phalacrocorax auritus ) dosed orally or dermally with artificially weathered Mississippi Canyon 252 crude oil

“…In the dermally exposed birds, an increased number of birds had thyroid gland lesions which may be directly induced by components of weathered MC252 crude oil or secondary to feather damage and increased need for metabolic heat production. While the histologic changes in the liver were minimal and likely represent a false negative, the change in organ weight combined with biochemical changes (Dean et al, 2017;Pritsos et al, 2017) indicate that the liver was also damaged. Results of the present study suggest that oral or dermal exposure of DCCOs to artificially weathered MC252 crude oil induced organ damage that could adversely affect survivability.…”

“…There were significant differences in absolute and relative liver weight with minimal histopathologic changes which generally occurred in birds from all three groups; despite statistically significant changes in hepatic biochemical endpoints including decreased AST, ALT, and GGT activities (Dean et al, 2017). The increases in liver weight could indicate edema, inflammatory infiltrate, hypertrophy/hyperplasia, or similar potential changes because of oxidative damage (Duerr, 2013).…”

Weathered MC252 crude oil-induced anemia and abnormal erythroid morphology in double-crested cormorants ( Phalacrocorax auritus ) with light microscopic and ultrastructural description of Heinz bodies

“…No control animals exhibited anemia at any time during the study. Oil exposure also induced statistically significant changes in plasma clinical chemistries and gross findings at necropsy (Dean et al, 2017;Harr et al, 2017).…”

Effects of Repeated Sublethal External Exposure to Deep Water Horizon Oil on the Avian Metabolome

“…Our research builds on a recent suite of studies examining effects of exposure to DWH MC252 oil on various analytes and their physiological endpoints in multiple bird species 3 . In these studies, exposure to weathered MC252 oil resulted in changes in hematologic parameters, effects on multiple organs, cardiac function, feather damage, and increased heat loss and energetic demands 15–18 . In the current study, we further examine samples collected from an external oil dosing study conducted on Double-crested Cormorants ( Phalacrocorax auritus ; cormorant 19,20 ) to evaluate the effect of exposure to DWH MC252 oil on the avian metabolome.…”