The briefing, organized by SeaWeb and the US National Press Club in Washington, focused on the long-term implications of the spill, both on and off shore.
Out in the deep waters of the Gulf, the still-spewing oil is a threat to biodiversity, said Thomas Shirley, a specialist in Gulf of Mexico studies at Texas A&M University (TAMU). The quadrant of the Gulf that includes the BP well is home to the highest number of animal and plant species at depths of 1000 to 3000 metres.
Citing a survey conducted by the university just last year, Shirley described the area as "the biodiversity hotspot for the deep Gulf". TAMU catalogued fishes, molluscs, mammals, crustaceans, turtles and more – 1,728 animal species in all at those depths, of which 135 are unique to the area and 74 were listed as endangered or threatened before the spill.
Ecological fears and uncertainty are rampant and these concerns are justifiedThomas Shirley
Oil, being a complex mixture of hundreds of compounds, affects living organisms in various ways, Shirley said. Physically, oil can block air passageways, causing suffocation, can inhibit feeding, and can destroy the insulating properties of feathers and fur. Oil is, of course, toxic if ingested, and it can also damage skin. It can reduce fecundity, which might not be observed until years after the immediate crisis ends. Other indirect effects may include starvation higher up the food web if smaller prey species are decimated. Dispersants used on an unprecedented scale in the BP spill may themselves cause damage but no data are available concerning their effect on wildlife, he said.
"Ecological fears and uncertainty are rampant," Shirley concluded, "and these concerns are justified."
On land the situation is also worrying. "This region has been under siege for four decades," said Robert Twilley of Louisiana State University, because of conflicting approaches of the federal and state governments to managing the Mississippi River and the delta it created where it reaches the Gulf of Mexico.
Twilley, a professor of oceanography and coastal sciences, said that half the load of sediments historically carried by the Mississippi to form the delta's marshes and barrier islands is now trapped far upstream behind dams. What's more, due to channeling of the river through the port of New Orleans and beyond, the sediment that does make it down now bypasses the coastal wetlands and is dumped directly into deep water, doing no good. "Without these sediments," said Twilley, "shoreline barriers that represent the first line of defense are gone because oil is approaching from deeper Gulf waters."
Twilley said that he does not favour simply releasing the Mississippi to find its own direct way to the sea from upstream of New Orleans. After the 1927 flood, he said, Congress established that the river would be used for navigation and flood control, and that is settled. Twilley does, however, advocate controlled floods, "a very different approach to managing the river". At times of high river flow, water would be diverted into coastal basins, allowing sand and sediment to rebuild the landscape that has been lost. He noted that current and anticipated sea-level rise would further complicate such mitigation efforts.
• Deepwater Horizon Oil Spill: ERL Call for Papers
Environmental Research Letters (ERL) -environmentalresearchweb's sister product - would like to invite you to submit your research into the effects of the Deepwater Gulf oil spill to a dedicated focus issue. This issue will build a collection of research on the initial impacts of the disaster and is the perfect forum to present your work to a massive global audience.