By Carey L. Perry
On the third anniversary of the Deepwater Horizon incident, a diverse group of researchers gathered at Louisiana State University for a conference to discuss “Louisiana Research Perspectives on the Deepwater Horizon 2010 Spill: The Good, The Bad, and The Ugly.” Presenters included ecologists, geologists, physicists, sociologists, public health experts, economists, and fishermen, among others, who discussed research generated from the oil spill to date, with a strong focus on what has been learned and what new research questions the current knowledge has generated.
At the start of the conference, Woods Hole Oceanographic Institution (WHOI) scientists, Dr. Chris Reddy and Dr. John Teal, addressed attendees as the conference’s keynote speakers. Dr. Chris Reddy is a senior scientist in the WHOI's Department of Marine Chemistry and Geochemistry. Since April 2010, he has devoted much of his research efforts to studying the Deepwater Horizon oil spill in the Gulf of Mexico. He has studied numerous other oil spills around the world. Dr. John Teal, a well-known coastal wetland ecologist is Scientist Emeritus at WHOI. In addition to his numerous years of coastal marsh research, Dr. Teal has investigated the effects of hydrostatic pressure on deepsea animals, the physiology of large, warm-blooded fishes, bird migration over oceans, wastewater treatment, and oil pollution.
In his keynote address, Dr. Reddy provided a narrative to attendees about how he initially got involved a few days after the spill and gave accounts of interesting oil spill research he completed after Hurricane Isaac came ashore along the Gulf Coast last year. He pointed out that hurricanes and tropical storms in the Gulf of Mexico have the potential to mobilize material from both offshore and near coastal environments, and as such, there was much speculation that Hurricane Isaac, which made landfall in late August 2012, contaminated Gulf beaches with oiled materials persisting from the 2010 Deepwater Horizon disaster. Signs of oil did wash up along Louisiana and Alabama beaches right after Hurricane Isaac. So, Dr. Reddy and colleagues led teams that scoured the beaches for those signs of oil in the form of sand patties and tar balls with the intent of discovering the oil's source. While reports appeared in the news that the sand patties and tar balls contained oil derived from the Macondo well that exploded in the Deepwater Horizon accident, Reddy's team conducted careful analysis and determined that sand patties and tar balls that were recovered from Elmer’s Island in Louisiana didn’t contain the fingerprints that linked them to the oil that was released from the Macondo well.
Similarly, following Hurricane Isaac, the media and other scientists speculated that the large, thick, black mats that showed up on Fort Morgan, Alabama beaches were directly linked to the Deepwater Horizon disaster. Again, through careful analysis, Dr. Reddy and his collaborators demonstrated that the mats contained organic matter, not oil. In fact, the mats were visually consistent with salt marsh peat that had washed onto the beaches after the hurricane. So, Dr. Reddy performed stable carbon isotope measurements and examined terrestrial plant wax signatures to confirm that the mats were dominated by near coastal salt marsh material as opposed to an offshore source. The mats contained only trace amounts of oil indicating that Hurricane Isaac did not mobilize oiled materials at Fort Morgan, but rather, disrupted a nearby marsh and brought peat onto the beach.
In September 2012, an oily sheen began to appear in offshore Gulf of Mexico waters near the site of the Deepwater Horizon disaster. Dr. Reddy and his team once again were called in to investigate the type and source of this sheen that appeared to be oil. Dr. Reddy’s tests showed the presence of alpha-olefins, a lubricant used in drilling mud, but not found in oil coming directly from a well reservoir. Based on their analysis, Dr. Reddy pointed out that the presence of alpha-olefins strongly suggested the oily sheen came from the wrecked oil rig itself and was not due to the release of additional oil from the Macando well.
Dr. Teal gave attendees an account of the multi-decadal effects of the 1969 Wild Harbor oil spill that occurred when the barge Florida ran aground near West Falmouth, Massachusetts spilling close to 200,000 gallons of fuel. At the time of the 1969 spill, lobsters, clams, and fish died by the thousands, but most people believed the harm would be temporary, reflecting the conventional wisdom of the time. Barge owners and oil industry experts even told residents that most of the oil would evaporate and any damage would only be short-lived. However, researchers at WHOI were not so sure and immediately began cataloging species and tracking where the oil was and kept at it for years. The researchers understood that the immediate, short term effects of oil pollution were already obvious and fairly well-understood, but that everyone was rather ignorant about the long-term and low-level effects of an oil spill.
The Wild Harbor spill is now one of the most well-studied oil spills in history, due to the excellent work of Dr. Teal and colleagues that began soon after the oil entered the harbor, and has continued for over 40 years. Beginning three to five years after the spill, marsh grasses and marsh animals were again occupying most of the oiled area. An observer unfamiliar with Wild Harbor would not have been able to visually detect the oiled areas after just 10 years, and by the second decade after the spill, the marsh's appearance had returned to normal. However, the WHOI researchers pointed out that for more than a decade after the spill, an oil sheen still appeared on the surface of the water when mud from the most heavily oiled parts of the marsh was disturbed.
In 2000, Dr. Reddy began an investigation of the long-term fate of the spilled oil in the marsh adjacent to the site where the Florida ran aground and oil washed ashore, the same marsh Dr. Teal and colleagues had been monitoring for years. Dr. Reddy’s research showed that fiddler crabs that normally burrow down deep in healthy marshes, funneling oxygen to the roots of marsh grass, stop digging when they reach oil, turn sideways, and then burrow back to the surface in the marshes that were oiled in the 1969 spill. Reddy’s team also demonstrated that fiddler crabs act disoriented from the oil they ingest, and are more easily caught by predators in the oiled marsh.
In 2007, WHOI researchers documented that a substantial amount of moderately degraded petroleum still remained within the sediment and along eroding creek banks of the marsh oiled in 1969. They also demonstrated that the ribbed mussels that inhabit the oiled salt marsh, and are exposed to the oil, exhibited slower growth rates, shorter mean shell lengths, lower condition indices, and decreased filtration rates even when placed in a healthy marsh. Researchers have also documented detrimental effects of the 1969 oil spill on the salt marsh plants themselves.
As Dr. Teal pointed out and Dr. Reddy’s findings highlighted, 40 years of research in Wild Harbor have taught us that oil doesn’t always go away after a spill. However, it is important to point out that the enormous Deepwater Horizon 2010 spill is far different than the smaller West Falmouth spill. The Louisiana spill spewed crude oil, not the lighter No. 2 diesel fuel that leaked out of the Florida; and unlike in Falmouth, the oil is not coming ashore quickly, which means there is time for it to be weathered by the sea and to lose some toxicity before entering near shore ecosystems.
Nevertheless, the two WHOI scientists, along with the day’s other numerous presenters, demonstrated the complexities associated with understanding the effects, both short- and long-term, of the 2010 Deepwater Horizon oil spill, and the societal misconceptions that surround such a disaster. Dr. Reddy urged those in attendance to look for the good that has been realized from this and past oil spill research, and pointed out to conference attendees the numerous opportunities for learning that have arisen from this tragic disaster. Dr. Teal, in sharing his many years of knowledge, opined “The best ecological engineers are Mother Nature and Father Time, but Father Time can sometimes take a long time,” as the lingering adverse impacts from the 1969 spill in Massachusetts have demonstrated.