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Oil in Marine Ecosystems:
Assessing the Risks
Coastal Marine Ecosystem Paper 2
Prepared by Dr. Craig Orr
British Columbians have enjoyed a moratorium on the human pursuit of offshore oil for three decades. Calls to rescind the moratorium have recently intensified, coincident with a downturn in local and provincial economies.
To some, offshore oil represents a quick fix. To others, including the Heiltsuk, oil might threaten what's more important a healthy ecosystem and a way of life. The Heiltsuk believe that the implications of lifting this moratorium deserve analysis and discussion, which is the purpose of this paper.
What follows here, is a brief examination of the potential consequences of oil spills and blowouts to the Heiltsuk's traditional marine territories. This paper, the second in a series on ecosystem and cultural integrity, affirms the need to carefully assess the risks that such narrowly-focussed actions might pose to our collective futures.
Proposed Drilling Area
The quest for oil would focus on Hecate Strait, the shelf area between Haida Gwaii and B.C.'s Central Coast. Experience suggests that seismic testing (using explosives) for potential well sites conducted along more than 5,000 km of transects poses a very real risk to benthic (bottom-dwelling) fishes and other organisms. Yet the major concern in the minds of most is the potential for spills (drilling, production, transportation).
Though no one can state what the precise threat is, we do know that Hecate Strait boasts some of the fiercest winds (exceeding 200 kph) and storms anywhere and that it has a history of major seismic activity, with quakes recorded up to magnitudes of 7.0 (1929 and 1970) and 8.1 (1949).
A Spilling History
We also know that marine oil spills occur. The 1989 Exxon Valdez spill released more than 35,000 tonnes of crude. In 1998, there were 176 spills reported world-wide. Britain's 1995 record was 458 tonnes of oil accidentally or deliberately discharged, an 8.3 percent increase from the previous year. Some experts suggest much of that oil has been discharged from ships flying "flags of convenience".
With major spills, there's little that can be done exept to track the oil's path and impacts. Scientists tell us that only the deep-dwelling or "benthic" organisms are likely to escape the coating effects of oil, a particular threat to intertidal organisms and marine mammals and birds. Prior to drilling off Canada's east coast, government and oil companies were required to spend millions assessing such potential ecological impacts.
Oil and Salmon: An Aromatic Story
Scientists are also telling us that oil may inflict its greatest damage on organisms such as salmon. The risks appear to come mainly from the polycyclic aromatic hydrocarbons contained in the oil. Polycyclic aromatic hydrocarbons (PAHs) are compounds formed when organic substances coal, oil, wood, gasoline are heated without sufficient air for complete oxidation. Heat causes the oil, composed of hydrogen and carbon, to shed its hydrogen, a process called aromatization. The resulting carbon atoms, shorn of hydrogen (aromatic), recombine into rings (polycyclic) that can be perilous to life.
PAHs were first shown to be carcinogenic in a 1775 study of chimney sweeps (specifically, the benzo[a]pyrene in soot). PAHs pose a particular threat to bioaccum-ulating organisms, depending on the size (molecular weight) of the PAH. The smaller PAHs (2 and 3 rings) are acutely toxic to many organisms, especially crustaceans and molluscs. PAHs adsorb to sediment and bioaccumulate in these organisms, which lack efficient mixed-function oxidase detoxification mechanisms.
PAHs with four or more rings (heavier molecular weights) have mutagenic (deform-causing) and carcinogenic effects. Such PAHs such as Benzo[a]pyrene is suspected of causing cancer by covalent bonding to guanine residues on DNA, which is thought to lead to errors in reading the genetic code during transcription.
National Marine Fisheries Service biologists in Alaska recently reported that PAHs might pose an extremely grave threat to Pacific salmon for many years after a spill.
These scientists found that:
A Coming Salmon Apocalypse?
Ultimately, the biggest threat oil may pose to salmon comes from burning the oil and from the oil's contribution to global warming. Many global climate models predict a doubling of CO2, and a 3° C temperature increase during next 50 years. For B.C.'s salmon, warmer temperatures are bad news spawning, incubation, and emergence are all influenced by stream temperature.
Dr. Kees Groot, a retired salmon scientist, predicts that a 3° C increase would shorten total incubation time (egg to emergence) in B.C. salmon by 55 to 131 days. Earlier emergence and emigration of salmon may, in turn, lead to:
In terms of a "life history strategy," it is better to be a bigger salmon than a smaller one. Provincial biologists have clearly shown that body size in juvenile steelhead is directly correlated with their chances of surviving to spawn. Size confers an advantage when competing for food, avoiding predators, and mating.
Salmon also exhibit well-defined temperatures preferences in the high Pacific.
Salmon temperature preferences in North Pacific waters
Winter < 7° C
A 3° C rise will decrease preferred habitat, and increase competition for both food and space. Ultimately, this means fewer salmon in our future. It might thus be time to consider using energy sources that are cleaner and less risky than B.C.'s offshore oil.
While inustry and others suggest that the risk is low, the Heiltsuk are concerned that oil exploration might still pose a threat to B.C.'s costal ecysystems from:
Alloway, B.J. and D.C. Ayres. 1993. Chemical Principles of Environmental Pollution. Blackie, Academic Press.
Feder, H.M. and A. Blanchard. 1998. The deep benthos of Prince William Sound, Alaska, 16 months after the Exxon Valdez oil spill. Marine Poll. Bull. 36: 118-130.
Groot, K. 1998. Climate Change and Pacific Salmon. P. 57-61 in Speaking for the Salmon.
Law, R.J., V.J. Dawes, R.J. Woodhead and P. Matthiessen. 1997 Polycyclic aromatic hydrocarbons (PAH) in seawater around England and Wales. Marine Pollution. Bull. 34: 306-322.
MacLaren Marex Inc., 1979. Oil spill contingency plan for well sites in the southern Gulf of St. Lawrence. Prepared for Hudson's Bay Oil and Gas Co. Ltd.
Orr, C.D. and R.M.P. Ward. 1981. The autumn migration of Thick-billed Murres near
Parfitt, B. 1999. A Crude Solution: Should the moratorium on offshore oil and gas development in BC be lifted? Prepared by Sierra Legal Defence Fund for the Living Oceans Society and Greenpeace.
Petroleum resource potential of the Queen Charlotte Basin and environs, west coast Canada. 1995. Geological Survey of Canada.
Prince Rupert Daily News. November 13, 1998. "Clark says moratorium needs debate."
Reuters. October 5, 1998. "Lingering Exxon oil harms salmon, scientists say."
Ward, B.R., P.A. Slaney, A.R. Facchin and R.W. Land. 1989. Size-based survival in steelhead trout (Oncorhynchus mykiss): back-calculated lengths from adults' scales
About the Author and Series
Dr. Craig Orr is a behavioural ecologist who has worked on salmon conservation issues in B.C. for more than a decade. Orr, who has also worked as a seabird ecologist, currently provides advice on selective fishing and water flow issues to the BC Aboriginal Fisheries Commission, and is a member of the board of the Habitat Conservation Trust Fund and Grizzly Bear Trust Fund. He is also president of Watershed Watch Salmon Society.