When at least 2,700 litres of oil poured out of the grain carrier MV Marathassa anchored in English Bay adjacent to Vancouver on April 8, British Columbians were shocked to see familiar beaches, waterways and even seabirds impacted by the toxic, leaked bunker C fuel.
Luckily, to date there has been no indication that any marine mammals were impacted by the event, but reports submitted to the B.C. Cetacean Sightings Network, a conservation and research program of the Vancouver Aquarium, indicated that an interaction between threatened Bigg’s killer whales and oil may have been closer than many realized. Reports submitted in the days following the spill indicate that a small pod of killer whales was spotted in nearby Howe Sound on the day of the spill as well as several days later. While these whales were not in a region impacted by oil, they may have been as close as 15 kilometres away.
The close proximity of the whales to the spill site is a stark reminder that even in our busiest ports, marine wildlife can occur and spills have the potential to cause devastating effects to these species. Unfortunately, due to major spills in other parts of the world, scientists know all too well the fatal effects oil can have on cetaceans.
Cetaceans do not appear to detect and avoid areas affected by oil. They have little, if any, sense of smell and are unable to detect oil vapour in the air. While they do have excellent eye sight, they don’t appear to recognize surface oil as a hazard. Oil vapour is very toxic and causes respiratory distress when inhaled. Whales are also in danger if they eat oiled prey. Bigg’s killer whales (transients) can consume oil adhering to the bodies and fur of their mammalian meals, and ingestion of oil can cause serious long-term damage to internal organs
The 1989 Exxon Valdez disaster in Alaska illustrated the damaging effects of oil specifically on killer whale groups. In the wake of this devastating accident, one pod of resident killer whales was photographed in an oil slick shortly after the spill and suffered the loss of 33 per cent of its members within a year. Its rate of reproduction has been lower than average ever since, and the pod fractured following the death of a matriarch. Additionally, members of the genetically unique AT1 transient population were also photographed in oil from the Exxon Valdez; 41 per cent of its members were lost in the following year. There has been zero reproduction in this group since the spill and this unique population is on the verge of extinction.
More recently, the Deepwater Horizon spill in the Gulf Mexico in 2010 has been associated with a higher than normal rate of cetacean mortality in the region, particularly among bottlenose dolphins. This spill has also caused long-term health effects among cetaceans. Dolphins in Barataria Bay, Louisiana, an area heavily impacted by oil, have been found to be five times more likely to have moderate-severe lung disease. Their symptoms are consistent with petroleum hydrocarbon exposure and toxicity.
With the recent English Bay fuel leak fresh on our minds, now is the time to begin taking action to reduce the threat to marine species, like the cetaceans, from future oil spills. What can you do?
-Reduce your oil and petroleum product consumption. Choose public transportation, walk or bike to get around, reduce your use of plastics (tips here and here), and take steps to increase the energy efficiency of your home.
-Choose locally grown and produced products. Shipping food and goods across the globe increases the number of freighters and the associated amount of fuel traversing our waters.
–Report your sightings of cetacean to the B.C. Cetacean Sightings Network to help us better understand and protect critical habitats.
References:
Matkin, C.O., Saulitis, E.L., Ellis, G.M., Olesiuk, P. And S.D. Rice. 2008. Ongoing population-level impacts on killer whales Orcinus orca following the ‘Exxon Valdez’ oil spill in Prince William Sound, Alaska. Marine Ecology Progress Series 356: 269-281.
Venn-Watson S, Garrison L, Litz J, Fougeres E, Mase B, et al. 2015. Demographic Clusters Identified within the Northern Gulf of Mexico Common Bottlenose Dolphin (Tursiops truncates) Unusual Mortality Event: January 2010 – June 2013. PLoS ONE 10(2): e0117248. doi:10.1371/journal.pone.0117248
Schwacke LH, Smith CR, Townsend FI, Wells RS, Hart LB, Balmer BC, Collier TK, De Guise S, Fry MM, Guillette LJ, Jr. et al. 2014. Health of Common Bottlenose Dolphins ( Tursiops truncatus ) in Barataria Bay, Louisiana, Following the Deepwater Horizon Oil Spill. Environmental Science & Technology 48(1):93-103.
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