Australian Oil Spill Threatening Sea Mammals

Oil slick from blowout during drilling off Australia. Photo: Chris Twomey, courtesy of WA Today, taken from SkyTruth. Loads of info on the spill here.

The leaking oil well in the Timor Sea is now officially a major environmental disaster, spanning at least 15,000 km2 (9320 mi2) and threatening marine wildlife, including whales and dolphins.

The well blew out on August 21, so as of September 11, 2009, it's been spewing oil for 21 days (click here for a web-counter tracking this spill). That would mean an estimated 2,646,000 gallons have been spilled so far.

Conservation groups continue to express concern about the giant slick, saying the entire area is ecologically significant. It is described as being part of an "ocean super highway" for migrating animals between the Indian and Pacific Oceans. Some populations are known to migrate through this region on their way to South East Asian waters. At least 20 different species of whales and dolphins probably use the area, including sperm whales, common dolphins, pygmy blues, and humpback whales.

Photos courtesy: Whale and Dolphin Conservation Society

The image seared into most of our minds are the images of oil-soaked seabirds washing onto beaches disoriented and helpless. When their feathers become clogged with oil, they lose their ability to insulate the bird from the cold and wet; prevent the bird from flying; hinder their ability to remain on the top of the water; and, they can become disoriented and drown.

Birds will constantly preen their feathers until they are squeaky clean - a trait that kills oil-soaked birds. By preening in a desperate effort to remove the oil, they ingest the toxic compounds in the oil and die.

Furred mammal face the same predicament - their fur protects them in much the same way as a bird's feathers do. Whales and dolphins use their blubber layer for insulation; and are not affected in this way. However this does not mean that they are not affected by oil spills.

Ingestion and inhalation may occur when animals are in close or direct contact with a spill. The large baleen whales can suffer from oiling of their baleen. Ingestion through prey and damage to the food web are also possibilities.

“Crude and other oils are mixtures of a great many organic compounds many of which are toxic, and animals can ingest oil-derived compounds either directly from the water or with their food. Poisonous vapours can also be inhaled and especially as the more volatile components evaporate into the air from freshly spilled oil” said Mark Simmonds, WDCS International Director of Science.

“Regrettably, whales and dolphins are unlikely to avoid oils spills and the more extensive the spill, the greater the encounter rate is likely to be. There will also be chronic effects of oil entering food-chains. Much of this is going to happen far away from the human eye and if whales or dolphins are killed or otherwise affected, we are unlikely to be witness to this. All of this further explains the need to keep fossil fuel plants out of important wildlife areas.”

Opportunistic observational research of wild animals has shown that the bottlenose dolphins observed during a fresh spill could detect slick and mousse oils; but, did not react to lighter sheen oil. Groups hesitated and milled about undecidedly when they encountered slick oil, eventually diving under small patches; but, continuing through extensive areas.

A recent whale survey, supported by the Wilderness Society and Horizontal Falls Seaplane Adventures, recorded 162 humpback whales in 102 separate pods south west of the spill area. A local whale researcher said this was just a snapshot, a tiny amount, of the number of whales that aggregate in this area to feed and give birth.

“This situation is dire and cetacean populations will come through this as the losers. This offshore spill is unlikely to result in animal bodies floating to shore, but the potential of impact must be assumed acted upon, rather than waiting for visible evidence” said Margi Prideaux, WDCS.