Geology topics

Dave Cacela

Publications and source records attributed to Dave Cacela.

3 recordsLinked to original sources

USGS2017

Overview of avian toxicity studies for the Deepwater Horizon Natural Resource Damage Assessment

The Oil Pollution Act of 1990 establishes liability for injuries to natural resources because of the release or threat of release of oil. Assessment of injury to natural resources resulting from an oil spill and development and implementation of a plan for the restoration, rehabilitation, replacement or acquisition of natural resources to compensate for those injuries is accomplished through the Natural Resource Damage Assessment (NRDA) process. The NRDA process began within a week of the Deepwater Horizon oil spill, which occurred on April 20, 2010. During the spill, more than 8500 dead and impaired birds representing at least 93 avian species were collected. In addition, there were more than 3500 birds observed to be visibly oiled. While information in the literature at the time helped to identify some of the effects of oil on birds, it was not sufficient to fully characterize the nature and extent of the injuries to the thousands of live oiled birds, or to quantify those injuries in terms of effects on bird viability. As a result, the US Fish and Wildlife Service proposed various assessment activities to inform NRDA injury determination and quantification analyses associated with the Deepwater Horizon oil spill, including avian toxicity studies. The goal of these studies was to evaluate the effects of oral exposure to 1–20 ml of artificially weathered Mississippi Canyon 252 oil kg bw -1 day -1 from one to 28 days or one to five applications of oil to 20% of the bird's surface area. It was thought that these exposure levels would not result in immediate or short-term mortality but might result in physiological effects that ultimately could affect avian survival, reproduction and health. These studies included oral dosing studies, an external dosing study, metabolic and flight performance studies and field-based flight studies. Results of these studies indicated changes in hematologic endpoints including formation of Heinz bodies and changes in cell counts. There were also effects on multiple organ systems, cardiac function and oxidative status. External oiling affected flight patterns and time spent during flight tasks indicating that migration may be affected by short-term repeated exposure to oil. Feather damage also resulted in increased heat loss and energetic demands. The papers in this special issue indicate that the combined effects of oil toxicity and feather effects in avian species, even in the case of relatively light oiling, can significantly affect the overall health of birds.

Ecotoxicology and Environmental Safety↗

USGS2017

CYP1A protein expression and catalytic activity in double-crested cormorants experimentally exposed to Deepwater Horizon Mississippi Canyon 252 oil

Double-crested cormorants ( Phalacrocorax auritus , DCCO) were orally exposed to Deepwater Horizon Mississippi Canyon 252 (DWH) oil to investigate oil-induced toxicological impacts. Livers were collected for multiple analyses including cytochrome P4501A (CYP1A) enzymatic activity and protein expression. CYP1A enzymatic activity was measured by alkoxyresorufin O-dealkylase (AROD) assays. Activities specific to the O-dealkylation of four resorufin ethers are reported: benzyloxyresorufin O-debenzylase (BROD), ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and pentoxyresorufin O-depentylase (PROD). CYP1A protein expression was measured by western blot analysis with a CYP1A1 mouse monoclonal antibody. In study 1, hepatic BROD, EROD, and PROD activities were significantly induced in DCCO orally exposed to 20 ml/kg body weight (bw) oil as a single dose or daily for 5 days. Western blot analysis revealed hepatic CYP1A protein induction in both treatment groups. In study 2 (5 ml/kg bw oil or 10 ml/kg bw oil, 21 day exposure), all four hepatic ARODs were significantly induced. Western blots showed an increase in hepatic CYP1A expression in both treatment groups with a significant induction in birds exposed to 10 ml/kg oil. Significant correlations were detected among all 4 AROD activities in both studies and between CYP1A protein expression and both MROD and PROD activities in study 2. EROD activity was highest for both treatment groups in both studies while BROD activity had the greatest fold-induction. While PROD activity values were consistently low, the fold-induction was high, usually 2nd highest to BROD activity. The observed induced AROD profiles detected in the present studies suggest both CYP1A4/1A5 DCCO isoforms are being induced after MC252 oil ingestion. A review of the literature on avian CYP1A AROD activity levels and protein expression after exposure to CYP1A inducers highlights the need for species-specific studies to accurately evaluate avian exposure to oil.

Ecotoxicology and Environmental Safety↗

USGS2000

PCBs, liver lesions, and biomarker responses in adult walleye (Stizostedium vitreum vitreum) collected from Green Bay, Wisconsin

Adult walleye were collected from several locations in the Lower Fox River and Green Bay, Wisconsin (the assessment area) and two relatively uncontaminated reference locations (Lake Winnebago and Patten Lake, Wisconsin) between July and October in 1996 and 1997. Whole body and liver samples collected in 1996 were analyzed for total PCBs, PCB congeners, and liver histological lesions. Follow-up sampling in 1997 included examination of liver histopathology, PCBs in liver samples, measurement of ethoxyresorufin-O-deethylase (EROD) activity, immunological evaluation of kidney and blood samples, measurement of plasma vitellogenin, and examination of tissues for parasites as well as bacterial and viral infections. Mean PCB concentrations in whole body and liver samples were elevated in assessment area walleye (4.6 to 8.6 and 3.6 to 6.4 mg/kg wet weight, respectively) compared to PCB concentrations in reference areas (0.04 mg/kg in walleye fillets from Lake Winnebago). A significant (p < 0.01) elevation was observed in the prevalence (26%) of hepatic preneoplastic foci of cellular alteration (FCA) and neoplasms in 5 to 8 year old walleye collected from the assessment area, compared to reference area fish (6% prevalence). Walleye from the assessment area also contained multiple FCA and hepatic tumors per liver sample, whereas no tumors and a reduced prevalence of FCA were observed in reference area walleye. Both tumors and FCA were more prevalent in female fish than in male fish within the 5 to 8 year age classes. There were no remarkable effects on immunological parameters in assessment area walleye, although hematocrit was elevated and blood monocyte counts were 40% lower than those of reference area fish. The data did not show any clear distinctions in the prevalence of disease between reference and assessment area walleye. EROD activity was similar in assessment area and reference area walleye. Plasma vitellogenin was elevated in female walleye from eastern Green Bay, but was not detected in male fish from this location. The results of this investigation demonstrate significant elevation in hepatic preneoplastic lesions and hepatocellular adenomas and carcinomas in assessment area walleye exposed to elevated concentrations of PCBs. These histopathological lesions are consistent with long-term exposure to tumor promoters such as PCBs, although quantitative association between tumors and PCBs was not observed at the level of the individual fish. Additional research would be needed to elucidate the causal mechanisms underlying tumorigenesis.

Wisconsin↗