Monday, November 02, 2009

How Much Will the Oil Spill Affect San Francisco's Estuary?

 An article from the weekend discusses some possible ecological effects of the latest oil spill in San Francisco Bay. Even though the spill was relatively small, recent droughts and toxic spills have made the bay particularly vulnerable.

The estuary that defines so much of life in the Bay Area faces increasing ecological pressures from polluted urban runoff, the vagaries of climate change and the effects of more fresh water pumped out of the Sacramento-San Joaquin River Delta. The herring season - the bay's last commercial fishery - was canceled last month because of concerns about the health of the fish population.

On Friday, ecologists were most immediately worried about the oil spill's effect on marshlands and rocky outcroppings where birds and fish congregate to feed and spawn, according to Deb Self, executive director of San Francisco BayKeeper. The areas of highest concern include Richardson Bay, Brooks Island off of Richmond, Keil Cove near Tiburon and the Emeryville Lagoon and mudflats.
It also looks at some specific groups that might be harmed by the bunker oil.
Once they're covered in oil, many birds die from toxicity and hypothermia. The oil interferes with the natural waterproofing effect of birds' feathers, making them more susceptible to cold. As they preen to get rid of the oil, birds often ingest the oil and sustain internal damage.

Farther down the food chain and earlier in the life cycle, oil spills can decimate certain marine species. Self and others say this year's canceled herring season may be due in part to the Cosco Busan spill.

Herring egg samples collected within the spill zone showed "high degrees of embryo mortality and abnormalities," according to recent research, while those collected outside the spill zone were largely normal. Because bunker oil breaks down slowly and is difficult to clean up, it can affect marine life for years.
Crabs were also affected by the last oil spill; this year's crab fishing season was shortened to protect the remaining population. It is unclear from the linked article how much other invertebrates suffered from the Cosco Busan spill. Some research projects on that question started soon after the spill. I am not sure if results have been published, but there is good reason to expect some harm among invertebrate communities.

In response to a question on my last post on the current spill, it is not yet clear who will pay the cleanup costs from the Cosco Busan spill, which are estimated to be $70 million. Earlier this year, both the ship's pilot and the operating company pled guilty to various charges related to the spill. The pilot received a prison sentence, and the company will pay a $10 million fine. That is clearly not enough to pay the cleanup costs. Responsibility for the remaining costs will be determined by a lawsuit filed by the federal, state, and local governments, plus private parties who suffered losses because of the spill.