concentrations of phytoplankton, the algal blooms that contribute to dead zones / photo: NASA

as in ‘HOW BIG is the DEAD ZONE this YEAR?’
Gulf ‘dead zone’ to be larger than average / June 30, 2010

The Gulf oil spill isn’t the only foreign substance that concerns ecologists who monitor the region. University of Michigan aquatic researcher Donald Scavia and his colleagues say this year’s Gulf of Mexico “dead zone” is expected to be larger than average. The 2010 forecast, released this week by the U.S. National Oceanic and Atmospheric Administration, predicts that the dead zone could measure between 6,500 and 7,800 square miles, equivalent to the size of Lake Ontario. Even at the low end of the range, the size of this year’s dead zone would be the 10th-largest on record. The average size during the past five years was about 6,000 square miles. The Gulf dead zone forms each spring and summer off the Louisiana and Texas coasts when oxygen levels drop too low to support most life in bottom and near-bottom waters. Farmland runoff containing fertilizers and livestock waste is the main source of the nitrogen and phosphorus that fuel the growth of algae blooms, that, in turn, create the dead zone. Scavia says it is unclear at this point what impact the Deepwater Horizon oil spill will have on the size of this year’s dead zone. If sufficient oil reaches the area typically subject to summer hypoxia, the size of this summer’s Gulf dead zone could increase for two reasons: microbial breakdown of oil — which consumes oxygen — and the oil’s potential to reduce diffusion of oxygen from the air into the water, the process that normally replenishes oxygen levels in the water column, Scavia said. The five largest Gulf dead zones on record have occurred since 2001. The biggest occurred in 2002 and measured 8,484 square miles. The official size of the 2010 Gulf dead zone will be announced following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium being held from July 24 through Aug. 2.

Oceans Running Low on Oxygen
by Andrea Thompson / 14 August 2008

Parts of the world’s oceans are running low on oxygen, a new study finds. Fertilizers and other chemical pollutants in river runoff fuel blooms of algae that cause oxygen levels to dip precipitously when they die. A review of research into these so-called “dead zones,” detailed in the Aug. 15 issue of the journal Science, finds that the number of dead zones has roughly doubled every decade since the 1960’s. The study authors, Robert Diaz of the Virginia Institute of Marine Science and Rutger Rosenberg of the University of Gothenburg in Sweden, tallied 405 dead zones in coastal waters worldwide today, affecting about 95,000 square miles (245,000 square kilometers) of ocean, an area about the size of New Zealand. While that may seem small compared to the total coverage of the oceans, the local effects can be devastating to marine ecosystems. These dead zones occur when fertilizer runoff dumps excess nutrients, such as nitrogen and phosphorous, into coastal waters, providing food for algae. When these microscopic plants die and sink to the ocean bottom, bacteria feed on them and subsequently consume all the oxygen dissolved in the water. This leaves fish and other bottom-dwelling sea creatures without enough oxygen to survive, causing mass die-offs and displacements. Typically, the researchers noted, these events aren’t noticed until they threaten valuable fish stocks. The world’s largest dead zone is in the Baltic Sea. The largest dead zone in the United States sits in the Gulf of Mexico at the mouth of the Mississippi River and is about the size of New Jersey. Scientists have predicted that the Gulf dead zone could grow larger than ever this summer. Diaz and Rosenburg said that dead zones now rank as one of “the key stressor[s] on marine ecosystems,” along with over-fishing and habitat loss. “There is no other variable of such ecological importance to coastal marine systems that has changed so drastically over such a short time as dissolved oxygen,” they wrote. With the possibility that climate change could exacerbate the situation through changes in ocean circulation, Diaz and Rosenburg recommend cutting back the amount of nitrogen-rich fertilizer that runs off into rivers.

Biologists find ‘dead zones’ around BP oil spill in Gulf
by Suzanne Goldenberg / 30 June 2010

Scientists are confronting growing evidence that BP’s ruptured well in the Gulf of Mexico is creating oxygen-depleted “dead zones” where fish and other marine life cannot survive. In two separate research voyages, independent scientists have detected what were described as “astonishingly high” levels of methane, or natural gas, bubbling from the well site, setting off a chain of reactions that suck the oxygen out of the water. In some cases, methane concentrations are 100,000 times normal levels. Other scientists as well as sport fishermen are reporting unusual movements of fish, shrimp, crab and other marine life, including increased shark sightings closer to the Alabama coast. Larry Crowder, a marine biologist at Duke University, said there were already signs that fish were being driven from their habitat. “The animals are already voting with their fins to get away from where the oil spill is and where potentially there is oxygen depletion,” he said. “When you begin to see animals changing their distribution that is telling you about the quality of water further offshore. Basically, the fish are moving closer to shore to try to get to better water.”

Such sightings – and an accumulation of data from the site of the ruptured well and from the ocean depths miles away – have deepened concerns that the enormity of the environmental disaster in the Gulf has yet to be fully understood. It could also jeopardise the Gulf’s billion-dollar fishing and shrimping industry. In a conference call with reporters, Samantha Joye, a scientist at the University of Georgia who has been studying the effects of the spill at depth, said the ruptured well was producing up to 50% as much methane and other gases as oil. The finding presents a new challenge to scientists who so far have been focused on studying the effects on the Gulf of crude oil, and the 5.7m litres of chemical dispersants used to break up the slick. Joye said her preliminary findings suggested the high volume of methane coming out of the well could upset the ocean food chain. Such high concentrations, it is feared, would trigger the growth of microbes, which break up the methane, but also gobble up oxygen needed by marine life to survive, driving out other living things.

Joye said the methane was settling in a 200-metre layer of the water column, between depths of 1,000 to 1,300 metres in concentrations that were already threatening oxygen levels. “That water can go completely anoxic [extremely low oxygen] and that is a pretty serious situation for any oxygen-requiring organism. We haven’t seen zero-oxygen water but there is certainly enough gas in the water to draw oxygen down to zero,” she said. “It could wreak havoc with those communities that require oxygen,” Joye said, wiping out plankton and other organisms at the bottom of the food chain. A Texas A&M University oceanographer issued a similar warning last week on his return from a 10-day research voyage in the Gulf. John Kessler recorded “astonishingly high” methane levels in surface and deep water within a five-mile radius of the ruptured well. His team also recorded 30% depletion of oxygen in some locations. Even without the gusher, the Gulf was afflicted by 6,000 to 7,000 square miles of dead zone at the mouth of the Mississippi river, caused by run-off from animal waste and farm fertiliser. The run-off sets off a chain reaction. Algae bloom and quickly die, and are eaten up by microbes that also consume oxygen needed by marine life. But the huge quantities of methane, or natural gas, being released from the well in addition to crude presents an entirely new danger to marine life and to the Gulf’s lucrative fishing and shrimping industry. “Things are changing, and what impacts there are on the food web are not going to be clear until we go out and measure that,” said Joye.

Deepwater Horizon blast triggered by methane bubble, report shows
by David Batty / 8 May 2010
The deadly blast on board the Deepwater Horizon oil rig in the Gulf of Mexico was triggered by a bubble of methane gas, an investigation by BP has revealed.

A report into last month’s blast said the gas escaped from the oil well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding. The sequence of events, described in the interviews with rig workers, provides the most detailed account of the blast that killed 11 workers and led to more than 3m gallons of crude oil pouring into the Gulf. Segments of the interviews conducted during BP’s internal investigation were described in detail to the Associated Press by Robert Bea, a University of California Berkeley engineering professor who serves on a National Academy of Engineering panel on oil pipeline safety. He also worked for BP as a risk assessment consultant during the 1990s. He received the details from industry friends seeking his expert opinion. The revelations came as a giant funnel was lowered over the oil well in a bid to contain oil leaking from it. BP said it may take up to 12 hours for the 98-ton, steel and concrete containment device to settle in place almost a mile (1.6km) below the surface. The company added that the operation appeared to be going as planned. If the procedure is successful, the device will hoover up 85% of the oil gushing from the ocean floor and pipe it into a tanker. But BP admits it is unclear whether its efforts will work. No containment box, or cofferdam, has ever been deployed at such depths and the operation is threatened by frigid ocean temperatures and the immense pressures. Meanwhile, crews have begun to drill a relief well, but that could take months. The outcome of the efforts to contain the oil could be critical to the future of offshore drilling in America. The Obama administration yesterday suspended new drilling in Alaska and Virginia. BP faces an equally daunting challenge to contain the political and financial fallout from the spill. Washington has kept up the pressure on the oil giant, a move seen in part as a tactic to divert criticism of its own role in the disaster. Recent news reports have suggested the interior department exercised lax oversight in approving BP’s operations in the Gulf, accepting too readily the company’s claims that there was little risk of an accident.

Methane in Gulf “astonishingly high”: U.S. scientist
by Julie Steenhuysen / Jun 22 2010

As much as 1 million times the normal level of methane gas has been found in some regions near the Gulf of Mexico oil spill, enough to potentially deplete oxygen and create a dead zone, U.S. scientists said on Tuesday. Texas A&M University oceanography professor John Kessler, just back from a 10-day research expedition near the BP Plc oil spill in the gulf, says methane gas levels in some areas are “astonishingly high.” Kessler’s crew took measurements of both surface and deep water within a 5-mile (8 kilometer) radius of BP’s broken wellhead. “There is an incredible amount of methane in there,” Kessler told reporters in a telephone briefing. In some areas, the crew of 12 scientists found concentrations that were 100,000 times higher than normal. “We saw them approach a million times above background concentrations” in some areas, Kessler said. The scientists were looking for signs that the methane gas had depleted levels of oxygen dissolved in the water needed to sustain marine life. “At some locations, we saw depletions of up to 30 percent of oxygen based on its natural concentration in the waters. At other places, we saw no depletion of oxygen in the waters. We need to determine why that is,” he told the briefing. Methane occurs naturally in sea water, but high concentrations can encourage the growth of microbes that gobble up oxygen needed by marine life. Kessler said oxygen depletions have not reached a critical level yet, but the oil is still spilling into the Gulf, now at a rate of as much as 60,000 barrels a day, according to U.S. government estimates. “What is it going to look like two months down the road, six months down the road, two years down the road?” he asked. Methane, a natural gas, dissolves in seawater and some scientists think measuring methane could give a more accurate picture of the extent of the oil spill. Kessler said his team has taken those measurements, and is hoping to have an estimate soon. “Give us about a week and we should have some preliminary numbers on that,” he said.

Bacteria help to clean up Deepwater Horizon spill
by Debora MacKenzie / 27 May 2010

Zoom in on the Deepwater Horizon oil slick and you will find a motley community of critters hard at work breaking down the oil: bacteria. At the annual meeting of the American Society for Microbiology in San Diego, California, this week, Jay Grimes of the University of Southern Mississippi in Hattiesburg reported that over the past few years, researchers have found that dozens of different kinds of marine bacteria have a healthy appetite for oil. He said that water samples from the Gulf of Mexico are showing signs that marine bacteria are already pitching in to help with clean-up efforts, and that populations of these bacteria in this area are likely to boom as they feast on the oil from the Deepwater Horizon disaster. Among these are members of the Vibrio family, which includes the species that causes cholera. Grimes cautions that there is no evidence that this species is one of those that breaks down oil, although other Vibrios that cause human infections do. “The Vibrios use breakdown products of oil,” says Rita Colwell of the University of Maryland in College Park. “When [the oil from Deepwater Horizon] reaches the estuary, Vibrios very likely will increase.”

Feasting bacteria
Colwell says that the greatest risk of bacterial infection in the Gulf comes from Vibrio fish pathogens and other species that commonly infect shellfish. Some of these can cause disease in humans. Grimes’s research department had the only research vessel, the R/V Pelican, on the scene until BP sent one in this week. It brought back samples of oil droplets that already had Vibrios clustered around them. Low oxygen levels were also detected near patches of oil, a sign that bacteria are feasting. Crucially, R/V Pelican happened to be in the area when Deepwater Horizon blew up. That means the team could immediately collect water samples to test for bacterial populations from areas that were threatened by the spill but had not yet been contaminated. The work is on-going and will be vital in future studies of how the spill has changed local ecosystems. “Now we plan to see how the microbial community evolves when you give it oil,” says Grimes. He hopes to screen bacteria from oil-affected water for the DNA of oil-eating enzymes, and use this to determine their species. “This blowout could permanently reshuffle the microbial community in the Gulf,” Grimes says. In previous research he found that Vibrio became the dominant type of marine bacteria off the south-eastern US as oil tanker traffic increased after the 1970s.

Long-term threat
For now the oil mainly threatens larval fish clinging to the underside of mats of seaweed. “I hope most of the oil will stay out to sea,” says Grimes. “It may kill a year’s production of fish, but if it hits the coastal marshes, it could be there for a decade.” At particular risk are coastal salt marshes. Ultimately, the tiny bacteria which Grimes and his colleagues are poring over will finish the Deepwater clean-up operation. Speaking at the San Diego meeting, Ron Atlas of the University of Louisville, Kentucky, said that the oil-eating microbes already present in seawater will be enough to get rid of any oil that is not physically removed by the clean-up crews – except for insoluble, tarry material that poses little toxic risk. Atlas, who managed the “bioremediation” of the 1989 Exxon Valdez spill in Alaska, says the bacterial process will be helped if fertiliser is added to the water, as then the oil-eaters will have the nitrogen and phosphate they need to grow. Fertiliser has already been used to aid the bacterial breakdown of oil that has hit the shore, but it could also help bacteria in the open sea if it is added to the detergents that are being used to disperse the oil. The fertiliser lodges in the surface of the oil droplets created by the detergents, he says – right where the bacteria can use them.

Pseudomonas aeruginosa growing on agar. The ‘NY3’ strain can help degrade polycyclic aromatic hydrocarbons (PAHs), one of the most harmful contaminants in oil spills.

New Strain Of Bacteria Could Aid Oil Spill Cleanup / Jun 15, 2010

Researchers have discovered a new strain of bacteria that can produce non-toxic, comparatively inexpensive “rhamnolipids,” and effectively help degrade polycyclic aromatic hydrocarbons, or PAHs – environmental pollutants that are one of the most harmful aspects of oil spills. Because of its unique characteristics, this new bacterial strain could be of considerable value in the long-term cleanup of the massive Gulf Coast oil spill, scientists say. More research to further reduce costs and scale up production would be needed before its commercial use, they added. The findings on this new bacterial strain that degrades the PAHs in oil and other hydrocarbons were just published in a professional journal, Biotechnology Advances, by researchers from Oregon State University and two collaborating universities in China. OSU is filing for a patent on the discovery. “PAHs are a widespread group of toxic, carcinogenic and mutagenic compounds, but also one of the biggest concerns about oil spills,” said Xihou Yin, a research assistant professor in the OSU College of Pharmacy. “Some of the most toxic aspects of oil to fish, wildlife and humans are from PAHs,” Yin said. “They can cause cancer, suppress immune system function, cause reproductive problems, nervous system effects and other health issues. This particular strain of bacteria appears to break up and degrade PAHs better than other approaches we have available.”

The discovery is strain “NY3” of a common bacteria that has been known of for decades, called Pseudomonas aeruginosa. It was isolated from a site in Shaanxi Province in China, where soils had been contaminated by oil. P. aeruginosa is widespread in the environment and can cause serious infections, but usually in people with health problems or compromised immune systems. However, some strains also have useful properties, including the ability to produce a group of “biosurfactants” called rhamnolipids. A “surfactant,” technically, is a type of wetting agent that lowers surface tension between liquids – but we recognize surfactants more commonly in such products as dishwashing detergent or shampoo. Biosurfactants are produced by living cells such as bacteria, fungi and yeast, and are generally non-toxic, environmentally benign and biodegradable. By comparison, chemical surfactants, which are usually derived from petroleum, are commonly toxic to health and ecosystems, and resist complete degradation.

Biosurfactants of various types are already used in a wide range of applications, from food processing to productions of paints, cosmetics, household products and pharmaceuticals. But they also have uses in decontamination of water and soils, with abilities to degrade such toxic compounds as heavy metals, carcinogenic pesticides and hydrocarbons. Although the type of biosurfactant called “rhamnolipids” have been used for many years, the newly discovered strain, NY3, stands out for some important reasons. Researchers said in the new study that it has an “extraordinary capacity” to produce rhamnolipids that could help break down oil, and then degrade some of its most serious toxic compounds, the PAHs.

Rhamnolipids are not toxic to microbial flora, human beings and animals, and they are completely biodegradable. These are compelling advantages over their synthetic chemical counterparts made from petroleum. Even at a very low concentration, rhamnolipids could remarkably increase the mobility, solubility and bioavailability of PAHs, and strain NY3 of P. aeruginosa has a strong capability of then degrading and decontaminating the PAHs. “The real bottleneck to replacing synthetic chemicals with biosurfactants like rhamnolipid is the high cost of production,” Yin said. “Most of the strains of P. aeruginosa now being used have a low yield of rhamnolipid. But strain NY3 has been optimized to produce a very high yield of 12 grams per liter, from initial production levels of 20 milligrams per liter.” By using low-cost sources of carbon or genetic engineering techniques, it may be possible to reduce costs even further and scale up production at very cost-effective levels, researchers said.

The rhamnolipids produced by NY3 strain appear to be stable in a wide range of temperature, pH and salinity conditions, and strain NY3 aggressively and efficiently degrades at least five PAH compounds of concern, the study showed. It’s easy to grow and cultivate in many routine laboratory media, and might be available for commercial use in a fairly short time. Further support to develop the technology is going to be sought from the National Science Foundation. “Compared to their chemically synthesized counterparts, microbial surfactants show great potential for useful activity with less environmental risk,” the researchers wrote in their report. “The search for safe and efficient methods to remove environmental pollutants is a major impetus in the search for novel biosurfactant-producing and PAH-degrading microorganisms.”

Xihou Yin
email : xihou.yin [at] oregonstate [dot] edu

What can BPC do to help fight the environmental crisis in the Gulf of Mexico? / May 2010

Oily water remediation (on-shore)
“Assuming the upper layer of the oil spill is collected and pumped on-shore for oil-water separation, BPC will plan and execute the complete cleaning process of the oily water. Following a preliminary physical separation, BPC can utilize its technology for rapid remediation of oily contaminants (both dissolved and emulsified oils). The pumped water can be treated in large tanks or basins that will be converted into bioreactors by BPC’s professionals in a matter of days.

This type of implementation will enable a semi-continuous or continuous treatment process, reduce the footprint of the treatment infrastructure and vastly increase its capacity. In addition, the treatment process uses a bacterial cocktail that contains only naturally-occurring bacteria specifically tailored for the cleaning of this type of contaminated water and features a control unit to monitor and automate the entire process. One of BPC’s control units is currently available in Freeport, Texas and can be shipped to the cleaning site in a matter of days. The bacterial cultivation can be performed on-site by BPC’s personnel contemporaneously with the preparation of the infrastructure. We estimate the set-up will take no longer than 2 weeks. BPC’s modular solution can be rapidly implemented and will provide immediate and positive impact.

On-site soil remediation
BPC’s bioremediation technology is also applicable for on-site remediation of oil and sand contaminated with oil. The process involves adding a bacterial cocktail of naturally occurring bacteria and a mixture of nutrients that will efficiently lower the contamination to safe levels, with visible results in a matter of weeks. Furthermore, the water treatment process described above can enhance the soil bioremediation process. This involves discharging the biologically treated water on the nearby contaminated soil or sand to provide a continuous feed of oil-consuming bacteria. The soil remediation process can be designed and executed in parallel or separately from the water cleaning process. One of BPC’s systems is currently available in Freeport, Texas and can be delivered to the site within days.

Oily water remediation (off-shore)
BPC’s innovative technology can be effectively used for off-shore remediation of contaminated sea water. BPC can introduce a mixture of bacteria and hydrophobic nutrients that have high affinity and are capable of degrading oil molecules. This will allow for efficient treatment at sea and partially overcomes the problematic effect of high dilution.

Quick and easy implementation
BPC can transform any tank or basin available along the coast line into a bioreactor. Furthermore, BPC has one of its skid-mounted control units currently available in Freeport, Texas, which will allow for its delivery and deployment within days.

Simple operation
BPC’s biological process is monitored and controlled by an automated control unit which allows for straightforward operation and eliminates the need for additional manpower.

Field-proven technology
BPC’s technology was developed by world-renowned Prof. Eugene Rosenberg, a pioneer in the field of microbial ecology and bioremediation processes. BPC’s technology has been implemented in various projects around the world for treating oily water and contaminated soil. With its local distributor in North America, BPC can deploy its technology and provide its treatment solutions rapidly.

High-capacity capability
Considering the large volumes of contaminated water that must be treated, BPC suggests implementing its technology in a continuous or semi-continuous mode with low-residence time. This will allow for continuous discharge of treated water back into the Gulf of Mexico and free up storage space for more contaminated water to be treated.

Wide-scale deployment
As the spill gradually spreads through the Gulf of Mexico, the need for several cleaning stations in strategic positions along the coast is inevitable. BPC’s experts can build and operate several cleaning stations in parallel or act as advisors for third parties that wish to implement the BPC technology.”

Chemosynthetic Community Locations in the Gulf of Mexico

Cold, Dark and Teeming With Life
by William J. Broad / June 21, 2010

The deep seabed was once considered a biological desert. Life, the logic went, was synonymous with light and photosynthesis. The sun powered the planet’s food chains, and only a few scavengers could ply the preternaturally dark abyss. Then, in 1977, oceanographers working in the deep Pacific stumbled on bizarre ecosystems lush with clams, mussels and big tube worms — a cornucopia of abyssal life built on microbes that thrived in hot, mineral-rich waters welling up from volcanic cracks, feeding on the chemicals that leached into the seawater and serving as the basis for whole chains of life that got along just fine without sunlight. In 1984, scientists found that the heat was not necessary. In exploring the depths of the Gulf of Mexico, they discovered sunless habitats powered by a new form of nourishment. The microbes that founded the food chain lived not on hot minerals but on cold petrochemicals seeping up from the icy seabed.

Today, scientists have identified roughly one hundred sites in the gulf where cold-seep communities of clams, mussels and tube worms flourish in the sunless depths. And they have accumulated evidence of many more — hundreds by some estimates, thousands by others — most especially in the gulf’s deep, unexplored waters. “It wouldn’t surprise me if there were 2,000 communities, from suburbs to cities,” said Ian R. MacDonald, an oceanographer at Florida State University who studies the dark ecosystems. The world’s richest known concentration of these remarkable communities is in the Gulf of Mexico. The life forms include tube worms up to eight feet long. Some of the creatures appear old enough, scientists say, to predate the arrival of Columbus in the New World.

Now, by horrific accident, these cold communities have become the subject of a quiet debate among scientists. The gulf is, of course, the site of the giant oil spill that began April 20 with the explosion of the Deepwater Horizon drill rig. The question is what the oil pouring into the gulf means for these deep, dark habitats. Seep researchers have voiced strong concern about the threat to the dark ecosystems. The spill is a concentrated surge, they note, in contrast to the slow, diffuse, chronic seepage of petrochemicals across much of the gulf’s northern slope. Many factors, like the density of oil in undersea plumes, the size of resulting oxygen drops and the potential toxicity of oil dispersants — all unknowns — could grow into threats that outweigh any possible benefits and damage or even destroy the dark ecosystems.

Last year, scientists discovered a community roughly five miles from where the BP well, a mile deep, subsequently blew out. Its inhabitants include mussels and tube worms. So it seems that researchers will have some answers sooner rather than later. “There’s lots of uncertainty,” said Charles R. Fisher, a professor of biology at Pennsylvania State University, who is leading a federal study of the dark habitats and who observed the nearby community. “Our best hope is that the impact is neutral or a minor problem.” A few scientists say the gushing oil — despite its clear harm to pelicans, turtles and other forms of coastal life — might ultimately represent a subtle boon to the creatures of the cold seeps and even to the wider food chain. “The gulf is such a great fishery because it’s fed organic matter from oil,” said Roger Sassen, a specialist on the cold seeps who recently retired from Texas A&M University. “It’s preadapted to crude oil. The image of this spill being a complete disaster is not true.” His stance seems to be a minority view.

Over roughly two decades, the federal government has spent at least $30 million uncovering and investigating the creatures of the cold seeps, a fair amount of money for basic ocean research. Washington has provided this money in an effort to ensure that oil development does no harm to the unusual ecosystems. Now, the nation’s worst oil spill at sea — with tens of millions of gallons spewing to date — has thrown that goal into doubt. The agency behind the exploration and surveying of the cold seeps is none other than the much-criticized Minerals Management Service of the Department of the Interior — not its oil regulators but a separate environmental arm, which long ago began hiring oceanographers, geologists, ecologists and marine biologists to investigate the gulf seabed and eventually pushed through regulations meant to protect the newly discovered ecosystems.

The minerals service is joining with other federal agencies to study whether the BP spill is harming the dark habitats. Scientists say ships may go to sea as soon as July, sending tethered robots down to the icy seabed to examine the seep communities and take samples for analysis. It is a bittersweet moment for scientists like Dr. MacDonald of Florida State University, who has devoted his career to documenting the ecosystem’s richness and complexity. In an interview, he said the sheer difficulty of trying to fathom the ecological impacts of the spill had left some of his colleagues dejected. “Once, we had this career studying obscure animals down there,” he said. “And now, it’s looking at this — probably for the rest of my career. It becomes this huge unknown.”

Inky darkness, icy temperatures and crushing pressures conspire to make studying the deep oceans arduous and remarkably costly. Humans are estimated to have glimpsed perhaps a millionth of the ocean floor. By contrast, people looking at the surface of the gulf have known about the seeping oil for centuries. Spanish records dating from the 16th century note floating oil. In the early 1980s, scientists investigating the oil seeps wondered if nearby creatures on the seabed might suffer chronic harm from pollution and serve as models for petrochemical risk. They lowered nets about a half mile down and pulled up, to their surprise, riots of healthy animals. “We report the discovery of dense biological communities associated with regions of oil and gas seepage,” six oceanographers at Texas A&M wrote in the journal Nature in September 1985.

The animals included snails, crabs, eels, clams and tube worms more than six feet long. The founding microbes of the food chain turned out to feed on seabed emissions of methane and hydrogen sulfide — a highly toxic chemical for land animals that has the odor of rotten eggs. Plants derive energy from sunlight and make living tissue in a process known as photosynthesis. The corresponding method among the microbes of the dark abyss is known as chemosynthesis. The minerals service proceeded to finance wide expeditions. It issued thick reports in 1988, 1992 and 2002. By then, scientists had discovered dozens of seep communities and found some of their inhabitants to be extraordinarily old. In the journal Nature, Dr. Fisher of Pennsylvania State University and two colleagues reported that gulf tube worms could live more than 250 years — making them among the oldest animals on the planet.

The latest expeditions have looked at seep communities as deep as 1.7 miles — far down the continental slope toward the gulf’s nether regions. In an interview, Dr. Fisher said investigations of the deeper communities suggested that tube worm species there grew slower and lived longer. How long? “It’s likely they can live a lot longer,” he answered. “I’m uncomfortable with an exact number, but we’re talking centuries — four, five or six centuries.” Over the years, scientists have found that the deep microbes not only eat exotic chemicals but also make carbonate (a building block of seashells) that forms a hard crust on the normally gooey seabed. The carbonate crusts can grow thick enough, they say, to reduce the flow of gas and oil through the seep communities and form attachment points for a variety of other sea creatures, especially deep corals and other filter feeders like brittle stars.

By probing the gulf’s deep waters with sound and other imaging technologies, scientists have found evidence for the existence on the northern continental slope of roughly 8,000 regions of hard crust — all, they say, potentially home to old or new seep communities. On its Web site, the minerals service freely admits “a management conflict” between encouraging oil development and protecting the dark ecosystems. It issued regulations in 1989 and has periodically toughened the rules, most recently in January. Now, in the wake of the oil disaster, many seep researchers have voiced strong concern about the threat to the dark ecosystems. Dr. Fisher said that thick oil could coat the respiratory structures of the animals and cause them to suffocate, and that high concentrations might otherwise prove toxic.

Samantha B. Joye, a cold-seep scientist at the University of Georgia, told a House science subcommittee on June 9 that the BP blowout represented “an unprecedented perturbation to the Gulf of Mexico system.” She expressed particular concern about the dispersants that BP is injecting a mile down into the spewing oil — in a largely successful effort to reduce the flow reaching the surface. Dr. Joye said the surge of oil into subsurface waters could feed microbes that consume oxygen. If their numbers explode, she said, the result could be a spike in oxygen consumption so large that its deep levels drop precipitously. The dark ecosystems, she noted, “can tolerate reduced oxygen concentrations.” But she cautioned that the BP spill will challenge their tolerance “beyond any previous insult.”

Now, oceanographers are preparing to dive deep to see how the dark communities are holding up. The lessons for oil precautions and regulatory care, they say, could have application not only for creatures in the inky depths of the Gulf of Mexico but also around the world. “Everywhere they looked, they’ve found them,” said Norman L. Guinasso Jr., director of Geochemical and Environmental Research at Texas A&M. He cited discoveries of seep communities off Angola, Indonesia and Trinidad. In exploring the gulf, Dr. Guinasso said, scientists are struggling to fathom the strengths and vulnerabilities of some of the planet’s oldest and most novel creatures. “People,” he said, “are still learning.”