The impact of the 1993 Braer oil spill on grey seals in Shetland

Review of petroleum toxicity and identifying common endpoints for future research on diluted bitumen toxicity in marine mammals

Large volumes of conventional crude oil continue to be shipped by sea from production to consumption areas across the globe. In addition, unconventional petroleum products also transverse pelagic habitats; for example, diluted bitumen from Canada's oilsands which is shipped along the Pacific coast to the United States and Asia. Therefore, there is a continuing need to assess the toxicological consequences of chronic and catastrophic petroleum spillage on marine wildlife. Peer-reviewed literature on the toxicity of unconventional petroleum such as diluted bitumen exists for teleost fish, but not for fauna such as marine mammals. In order to inform research needs for unconventional petroleum toxicity we conducted a comprehensive literature review of conventional petroleum toxicity on marine mammals. The common endpoints observed in conventional crude oil exposures and oil spills include hematological injury, modulation of immune function and organ weight, genotoxicity, eye irritation, neurotoxicity, lung disease, adrenal dysfunction, metabolic and clinical abnormalities related to oiling of the pelage, behavioural impacts, decreased reproductive success, mortality, and population-level declines. Based on our findings and the body of literature we accessed, our recommendations for future research include: 1) improved baseline data on PAH and metals exposure in marine mammals, 2) improved pre- and post-spill data on marine mammal populations, 3) the use of surrogate mammalian models for petroleum toxicity testing, and 4) the need for empirical data on the toxicity of unconventional petroleum to marine mammals.

Pathological Findings in Harbour Seals ( Phoca vitulina ): 1996–2005

Between 1996 and 2005 the carcasses of 355 harbour seals originating from the coast of Schleswig-Holstein, Germany, were investigated for pathological changes. The animals were collected before (n=280) and after (n=75) the second phocine distemper virus (PDV) epizootic in 2002. The seals were either found dead or were killed due to severe illness. Necropsy was performed in each case, in addition to histopathological, immunohistochemical, microbiological and parasitological examinations. Throughout the period of study, the respiratory and alimentary tracts were the organ systems most consistently affected by pathological change. The most common cause of death was bronchopneumonia caused by parasitic and/or bacterial infection of the lung. Less frequently identified changes included: trauma, gastroenteritis, uterine torsion or dystocia, polyarthritis/polymyositis, intestinal torsion, septicaemia, dermatitis, and keratitis. The most frequent causes of bronchopneumonia, gastroenteritis, polyarthritis, dermatitis and septicaemia were infections with alpha/beta-haemolytic streptococci, Escherichia coli and Clostridium perfringens. A number of changes were more frequently identified after 2002. These included the presence of parasites in the lung, stomach and intestine; bronchopneumonia, gastritis, enteritis, septicaemia and perinatal death. The increased prevalence of these changes may have been related to the preceding PDV epidemic.

Impacts of the Jessica oil spill on sea lion (Zalophus wollebaeki) populations

Following the Jessica oil spill, a total of 79 oiled Galápagos sea lions (Zalophus wollebaeki) were recorded around the islands of San Cristóbal, Santa Fé, Isabela and Floreana. Almost half of these animals required washing and other treatment. One sea lion death and a high incidence of conjunctivitis and burns were detected during the period of the oil spill. Sea lion populations exhibited a tendency for decline in the first months following the spill at all three colonies monitored close to the grounding site on San Cristóbal. By comparison, declines of similar magnitude occurred at only one of six sea lion colonies monitored on islands more distant from the spill. However, no significant decreases in population numbers were detected for any colony in the year following the spill. Galápagos sea lion populations were partially recovering from the much more catastrophic impact of the 1997/98 El Niño.

An overview of exposure to, and effects of, petroleum oil and organochlorine pollution in grey seals (Halichoerus grypus)

Most incidences involving oil pollution of grey seals (Halichoerus grypus) seem to have occurred at the breeding sites. Because of the high concentration of animals at this time, even small oil spills will pollute many animals. As a result of chronic low-level pollution from coastal ship traffic and discharges from offshore petroleum activity in the North Sea, approximately 50% of the grey seal pups at the largest breeding colony in Norway are polluted each year by oil. In this case, as well as in other similar cases of spills at breeding colonies, oil has produced little visible disturbance to the seals behaviour and there has been little mortality. The effects and mortality may, however, be more serious following a spill of crude oil, where animals may be affected by inhalation of toxic volatile compounds. High body burdens of PCBs and DDTs seem to have caused skull-bone lesions and occlusions of the uteri in grey seals in the Baltic Sea. Exposure to these persistent compounds has also been suspected to be the cause of reduction in the population of Baltic grey seals. There are indications that thyroid hormone and vitamin A status of grey seal pups are affected by the low exposure concentrations experienced at the Norwegian coast (approximately 1/20 of the concentration detected in grey seal pups from the Baltic Sea). This gives serious cause for concern about the effects that chronic low-level exposure to persistent organochlorine pollutants may have on individuals and on populations of grey seals.