The Deepwater Oil Release Impact on Marine Life
New reports are surfacing every day about the immediate impacts of the Deepwater Horizon oil spill on Gulf Coast wildlife, especially as the oil reaches the sensitive marshlands along the coast. What will be the long term impact to local marine life? There is some knowledge from earlier releases such as Valdez off Alaska. Oil contains complex hydrocarbons and heavy metals. Such materials will be absorbed and have impact on the local marine life over time. How they will be absorbed, how much and their effects are unknown or debatable. To begin to address this issue, Academy scientist Peter Roopnarine is working with Laurie Anderson from Louisiana State University and David Goodwin from Denison University to collect and analyze three different types of mollusks from the Gulf Coast. These animals are continually building their shells, and if contaminants are present in their environment, they can incorporate those compounds into their shells.
Roopnarine and his colleagues will study growth rings in the shells (similar to tree rings) to determine how quickly harmful compounds from the oil become incorporated into the animals' homemade armor. They will also sample tissues from the animals over the next four months to test for hydrocarbons, and will measure changes in growth rate and survivors.
We have analyzing shellfish from across the Bay over the past three years, and we have documented that the animals from the more polluted areas, like the waters around Candlestick Park, have incorporated vanadium and nickel into their shells - two metals that are common in crude oil. It appears that the metals can be substituted for calcium as the animals build their calcium carbonate shells." says Roopnarine, Curator of Geology at the California Academy of Sciences.
By studying these shellfish in the Gulf, the scientists will be able to monitor three different pathways for hydrocarbons/metals into the food web, since oysters are stationary filter feeders that eat plankton, clams are stationary bottom feeders that eat mostly detritus, and periwinkles are mobile grazers that algae.
As primary consumers in the food chain, oysters, clams, and periwinkles will likely be among the first animals to accumulate hydrocarbons and heavy metals. These compounds released during an oil spill may get passed on to the marine organisms that feed on shellfish. Hydrocarbons are organic compounds that will break down over time, but the long term impacts of heavy metals like vanadium and nickel in the food web are unknown.
There have been other oil releases. In 1978, an oil tanker, the Amoco Cadiz, split in two about three miles off the coast of Normandy, releasing about 227,000 tons heavy crude oil that ultimately stained nearly 200 miles of coastline. The spill site was so large that only the areas of greatest economic impact were treated with detergents. Large areas in the more remote parts of the coast went untreated. Untreated areas recovered more quickly than treated (dispersant) areas even after 30 years.
In March of 1989, the oil supertanker Exxon Valdez spilled 11 million gallons of crude oil into the Prince William Sound and impacted some 1,300 miles of coastline. It remains the largest oil spill in U.S. history.
A combination of detergents and bioremediation were used in the clean up. The detergents were nutrient rich, being high in phosphorous and nitrogen compounds. After the first year, the treated areas were cleaner. Long term prospects for the treated area are not as clear. These treatment compounds were high in nutrient values but went into a low nutrient environment. This upset the local ecological balance even though the major intrusive effects of the oil were diminished.
The Exxon Valdez Oil Spill Trustee Council issued a study in 2004 on the recovery status of local marine life. The results are suggestive of potential long term effects in the Gulf Of Mexico. However, all depends on the decisions made on treatment and sopping the oil flow. As can be seen the results are mixed.
Not recovering or showing little or no clear improvement since the spill are: Common loon, Cormorants, Harbor seal, Harlequin duck, and Pacific herring.
Not clear due to limited data are: trout and Kittlitz’s murrelet.
Recovered species include: Bald eagle, Black oyster catcher, Pink salmon, river otter, and Sockeye salmon.
Still recovering were: Clams, killer whale, mussels and sea otter.
For further information: http://www.sciencedaily.com/releases/2010/05/100524143425.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader