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Zooplankton Among First To Show Evidence Of Exposure To Deepwater Horizon Oil

March 23, 2012

Ryan Parson for Redorbit.com

Oil remnants from the Maconda-1 oil field have been discovered in animals in the northern Gulf of Mexico.

Zooplankton samples collected from the Gulf of Mexico have shown positive evidence of exposure to oil that may have directly originated from the Deepwater Horizon oil spill.

The effects of the deadly British Petroleum R/V Deepwater Horizon oilrig explosion that took place on April 20, 2010, will more than likely be present for many years to come.

From April 20 to July 15, the damaged rig continuously spilled an estimated 53,000 barrels of crude oil into the water of the Gulf of Mexico every day.

According to the National Oceanic and Atmospheric Administration (NOAA), by the time the well was capped, approximately 4.9 million barrels of crude oil were being spread throughout the water by the tides and currents.

There is no way to know exactly how this tragic event will affect the Gulf environment and all the organisms that inhabit the vast body of water. Though, researchers have been working tirelessly to figure out just what the main consequences will be.

A team of scientists, from a number of different institutions, has been using the smallest of marine animals, zooplankton, and have found evidence of polycyclic aromatic hydrocarbons (PAHs) in these animals.

Zooplankton are the minute, often microscopic, animals that live in the water column.  The members of this family of plankton include copepods, krill, and the larval forms of many animals such as urchins, crab, shrimp, snails, and fish.  Since these animals are so small, they comprise the very bottom level of the food chain. Therefore, zooplankton play a huge role in the diet of every creature living in the water, from the smallest fish to giant whales.

The National Research Council describes PAHs as a group of organic compounds that are generally found in petroleum and fossil fuels.  Some PAHs have been identified as having hazardous and harmful properties.  Using technology such as gas chromatography and mass spectroscopy, researchers are able to tell what elements make up the PAHs in question and the exact quantity that is present. Using this information, they can get a detailed “fingerprint” of the PAHs that were found in oil that spilled from the Maconda-1 well and compare that data to the fingerprints of the samples from the collected zooplankton.  With this fingerprint data, they are able to determine the general location from which the oil was originated.  It was determined that the PAHs present in the zooplankton did come from the Maconda-1 area, linking it the Deepwater Horizon spill.

Dr. Siddhartha Mitra of Eastern Carolina University stated, “Our research helped to determine a ℠fingerprint´ of the Deepwater Horizon spill–something that other researchers interested the spill may be able to use.  Furthermore, our work demonstrated that zooplankton in the Northern Gulf of Mexico accumulated toxic compounds derived from the Macondo well.”

The study showed that the fingerprint linked to the Deepwater Horizon spill could be found in small amounts as early as a month after the gushing well was capped.  Scientists in the future will be able to utilize this fingerprint to link traces of oil and PAHs to the Gulf oil spill.

Now what does this mean for us humans?

Since the zooplankton animals that were exposed to the hydrocarbons are at the bottom of the food chain, virtually every other link in the food chain will also be subjected to the PAHs that entered the chain from the very bottom.  Although there is only a minute amount of the hydrocarbons in the zooplankton, the further up an animal is in the food chain the greater quantities of PAHs the organisms ingest.  So ultimately, as the PAHs move higher in the food chain, the exposure of these larger fish occurs in greater concentrations.

According to Dr. Michael Roman with the University of Maryland Center for Environmental Science, “Traces of oil in the zooplankton prove that they had contact with the oil and the likelihood that oil compounds may be working their way up the food chain.”

Many animals are not exclusive to just one area or habitat, but travel large distances to different areas causing the PAH contamination to spread large distances over a period of time.  This is evident from the study, showing that samples that were collected further away from the site of origin also contained evidence of contamination.

As members of the same food chain, this makes it possible for humans to be exposed to the PAHs as well, though the full effects from exposure are unknown.

The Centers for Disease Control and Prevention (CDC) states that PAHs are lipid soluble and can be absorbed through the skin, respiratory tract, and gastrointestinal tract.  High degrees of exposure are also thought to cause some birth defects.  Studies concerning PAHs have been conducted on animals and have shown to cause kidney and brain toxicity after subjected to high doses, but the full effects on humans are still unclear.  One of the components that make up crude oil is fluoranthene, and according to OSHA has also been tested on animals and was determined to be a known carcinogen.

The research concerning the Maconda-1 oil spill and the effects it will have on the environment and in the food chain is essential in the determination of the solutions that should take place when such devastating events occur.  Even though the oil is no longer visible on the surface of the water, it is by no means gone for good!

The National Wildlife Federation reports that scientists have found significant amounts of oil on the seafloor of the Gulf of Mexico.  The oil that has already found its way to the very delicate and intricate environments of wetlands, estuaries, and beaches will likely be present for many years, which creates a very serious challenge when trying to create successful cleanup and restoration plans.  To further escalate the situation, the disaster occurred at the peak of breeding season for much of the wildlife in the area, and could have devastated the egg and larval forms of many species of organisms causing detrimental effects in that brood class of fish.  The animals most largely affected in the food chain will only become evident in the years to come.

The paper, “Macondo-1 well oil-derived polycyclic aromatic hydrocarbons in mesozooplankton from the northern Gulf of Mexico,” was published in the February issue of Geographical Research Letters. It can be found here.


Source: Ryan Parson for Redorbit.com



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