Wednesday, June 30, 2010

Fish as brain food helped homo become sapiens?

Fish as brain food helped homo become sapiens?

What gave rise to the rapid brain size increase that made us ‘thinking' men? The answer: we began eating fish

One of the puzzles in biology is how rapid the human brain developed.

It took hardly a million or so years for us to become the “thinking man” or homo sapiensfrom our immediate ancestors and cousins, the homo habilis, erectusorrudolfensis. How do we know this?

From a comparison of the brain to body ratio. While the other homoshad a brain volume of 600-800 ml (based on skull size), we have about 1250 ml, and all for roughly the same body size.

Thus, we have far more within our head than our immediate ancestors or the chimpanzees (brain about 410 ml).



A recent paper by Dr. David Braun and colleagues in the June 1, 2010 issue of the Proceedings of the National Academy of Sciences, USA, reports on the historical evidence of a large collection of fish bones near a putative settlement of homo, dated to about 1.95 million years ago, in the Rift Valley of Africa. This is the area from where we humans are thought to have originated.

And the fish bones they found had bite marks matching those of human (and not great ape) teeth.

Why is this paper important? For this, may I refer you to an excellent review article by Drs. C L Broadhurst, S.C. Cunnane and M A Crawford that appeared 12 years ago in the British Journal of Nutrition (1998; 79:3-21), a review that reminds us of the logic of Sherlock Holmes?


Also note that fish contain those vital nutrients that the brain needs in order to develop and grow. The human brain is “oily”, containing as much as 600g of lipid per kg, with long chain fatty acids like arachidonic acid (AA) docosa-hexenoic acid (DHA), that the body does not produce; they are thus “essential nutrients” – and fish have them in good measure.

So then, where do vegetarians get their essential lipids from?

From green vegetables, walnuts and peanuts, sesame and mustard, cotton, sunflower and other oil sources. And this is why modern-day nutritionists insist on our intake of poly-unsaturated fatty acids (PUFA), rather then Dalda or trans-fats.


Note too that meat (pork, beef, chicken and such) is muscle or protein-rich. The fat content meat has is not the type that feeds the brain. It is, as my granddaughter Kimaya says, “body food” while nuts, fish or greens are “brain food”. Thus in having chanced upon eating fish, homos had struck the jackpot, in comparison to the largely veggie primates or the carnivorous animals in the neighborhood.


Biologists find 'dead zones' around BP oil spill in Gulf

Biologists find 'dead zones' around BP oil spill in Gulf

Methane at 100,000 times normal levels have been creating oxygen-depleted areas devoid of life near BP's Deepwater Horizon spill, according to two independent scientists.

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.


Diatoms can provide the oxygen required by bacteria.

Monday, June 28, 2010

Bioremediation of Oil Spills - Oxygen requirement

Bioremediation, the Gulf of Mexico oil leak,

In the Gulf of Mexico, bioremediation technologies have come into increased focus as the BP oil leak continues to gush, with up to 7 million barrels of oil now floating in the Gulf after an explosion at an offshore drilling platform in April. According to BioremXL, “bio-remediation transforms the contaminant into food for bacteria that, given the proper conditions, happily consume it. Most bio-remediation products typically become water-logged and sink to the bottom of the lake, stream, ocean, etc. where bacteria cannot grow due to lack of oxygen and sunlight, sometimes having the reverse effect of actually causing even more environmental damage by trapping the oil in an inaccessible place for many years to come.”

UniRem is touting its PRP (Petroleum Remediation Product), which creates miniature spheres comprised of bee’s wax and soy wax to naturally encapsulate oil so that bacteria can consume and transform it into organic matter. These miniature spheres (100 microns in diameter) float at the top of the water where the oil, oxygen, and sun are.


Evan Nyer of Arcadis cautions, “The key to bioremediation of the oil spill is Bacteria, nutrients, and oxygen. There are two schools of thought on the bacteria. One is that someone will make a “super bacteria” that is capable of eating all of the oil in the spill. I am sure that are several companies that are currently offering BP their super bacteria at a reasonable price. My thoughts on bacteria are that they are ubiquitous (everywhere) and that they can double in number every 30 minutes under the right environment conditions. The main things that limit that rate of growth are nutrients (Nitrogen and Phosphorous) and a final electron acceptor (oxygen). So – bacteria are not limiting the rate of bioremediation of the spill.

“Nutrients – during the cleanup efforts in Alaska, studies found that adding nutrients to the shoreline spill areas helped to clean up the oil in those areas. Of course these were in areas that had great wave action which provided the oxygen that the bacteria required. Limited nutrient addition may be able to help the clean up in certain areas.

“Oxygen – this is probably the limiting factor in the rate that the bacteria can eat the oil. The ocean and shore areas have limited ability to transfer oxygen into the water. The maximum oxygen concentration in water is 8 mg/l and we are talking about 100s or 1000s of mg/l of oil contaminant (the dispersants they are using also have to be degraded by the bacteria and add to the oxygen demand of the entire process). So the oxygen must be constantly replenished. This only happens at the air/water interface at the surface of the ocean. Anything that creates surface area and mixing will increase the rate of oxygen transfer. That is why a storm is good news/bad news. It will transfer huge amounts of oxygen, but the waves can help spread the spill. (The sulfate in the ocean can replace the oxygen in the bioremediation, but the bacteria that use sulfate require a very reducing environment and the ocean is not a reducing environment.)

“Tar Balls – In the end the bacteria can only degrade the lower molecular weight compounds from the crude oil. The tar balls cannot use bioremediation.”


Diatoms can provide the oxygen required by bacteria.

Anaerobic bacteria can use sulfur, but deep seas do not support anaerobic bacteria and they are in fact not desirable in deep sea.

Thursday, June 24, 2010

Rural sanitation in US

More than 160,000 of West Virginia's 900,000 homes may use straight pipes for sewage.

By Pam Kasey
Email | Bio | Other Stories by Pam Kasey

On or about July 5, the state and all its counties are going to be sued.

Those entities are allowing more than 160,000 of the state’s 900,000 homes to discharge raw sewage into streams in violation of the Clean Water Act, according to Atlanta lawyer William “Bo” Gray.

That’s nearly one-fifth of the homes in the state.


Is It Worse in West Virginia?

Jennifer Newland of the nonprofit Canaan Valley Institute, which provides wastewater technical assistance to rural communities, doesn’t believe so.

“If you find any rural, low-income community, they probably don’t have adequate treatment,” she said. She pointed to documentation of similarly pervasive problems in Kentucky, Minnesota and other states.

NESC Director Gerald Iwan, who has worked in Connecticut and New York, doesn’t believe so either.

It’s a problem for disadvantaged counties everywhere, he said.

“It begs the question, in a country as wealthy as we are, why do these problems persist?”


Nutrient and phytoplankton in German Bight

Long-term changes of the annual cycles of meteorological, hydrographic, nutrient and phytoplankton time series at Helgoland and at LV ELBE 1 in the German Bight

Radach, Gu¨Nther; Berg, Joachim; Hagmeier, Erik


Long-term series of meteorological standard observations at LV ELBE 1, together with those of temperature, salinity, plant nutrients and phytoplankton biomass at Helgoland Reede in the German Bight, are investigated with respect to the changes of the annual cycles during the 23 years from 1962 to 1984. Most meteorological and oceanographic parameters exhibit unchanged annual cycles within natural variability, except for the air and sea surface temperatures which show an overall increase of about 1°C per 23 years. Conspicuous changes in the annual cycles are observed for the nutrients phosphate, nitrate, nitrite (all strongly increasing) and silicate (decreasing). Phytoplankton biomass increased as a result of the extreme increase of flagellates, although diatoms decreased slightly. This and the shifting and shortening of the nutrient depletion phases are indicative of a strong change in the ecosystem. The changes seem mainly to be because of anthropogenic eutrophication, over-riding possible influences of large-scale climatic changes.

Wednesday, June 23, 2010

Xiamen's Yundang Lake - Diatom bloom

Xiamen's Yundang Lake becomes smelly due to red tide

Updated: 24 Jun 2010
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The bad smell of Yundang Lake, this unique lagoon in Xiamen
seems to be a chronic illness especially in summer
Recently Xiamens Yundang Lake has become smelly again due to the red tide. The nearby residents have to close their windows because of the undesirable odour, reports Xiamen Daily.
Red tide is a term often used to describe harmful algal bloom. The Skeletonema costatu (one kind of diatom) is the cause of this red tide in Yundang Lake. The proliferated diatoms have tinted the water of Yundang Lake to a reddish colour.
The staff of Yundang Lakes Management Centre said: As weather warms up, the micro-organisms at the bottom of the lake become active and generate a great quantity of gas with afoul odour. The increasing micro-organic activities will bring up the ooze, which will intensify the bad smell.
To solve this problem, the Management Centre has taken many effective measures to deodorizethe lake, including the installation of odour control facilities, the use of automatic aerators and biologicals. Another frequently-used way is to eliminate the diatom oozes.
After long-term purification, the frequency of the red tide has become much lower this year, according to the Management Centre.


Lake seems to be dominated by only 1 specie of diatom.
Presence of fish in the lake is not mentioned in the article above.

Nutrient controls contributing to Karenia Brevis blooms in the Gulf of Mexico.

Nutrient controls contributing to Karenia Brevis blooms in the Gulf of Mexico.

by Jason Lenes, et. al.

Slides 13, 14 and 15 discuss the results of a case study in 2001.

Increase in Si resulted in a 50% fall in K. brevis biomass.

Monday, June 21, 2010

Diatoms in US waterways - L G Williams


Louis G. Williams and Carol Scott

National Water Quality Network, U. S. Public Health Service, Cincinnati


  • Possible Relationships Between Plankton-Diatom Species Numbers and Water-Quality Estimates
  • Louis G. Williams
  • Ecology, Vol. 45, No. 4 (Oct., 1964), pp. 809-823
    (article consists of 15 pages)
  • Published by: Ecological Society of America
  • Stable URL:

  • Plankton Diatom Species Biomasses and the Quality of American Rivers and the Great Lakes
  • Louis G. Williams
  • Ecology, Vol. 53, No. 6 (Nov., 1972), pp. 1038-1050
    (article consists of 13 pages)
  • Published by: Ecological Society of America
  • Stable URL:

Ohio Sea Grant Research - Lake Erie diatoms

Newly discovered winter alga may be be linked to Lake Erie’s summertime event

by Stacy Brannan, Ohio Sea Grant Communications

With the winds howling and snow falling, it seems like few microscopic creatures could survive a winter in Lake Erie. But Ohio Sea Grant researchers Drs. Michael McKay, George Bullerjahn, and Scott Rogers of Bowling Green State University have discovered life under the icy surface in the form of the diatom Aulacoseira islandica—and they believe it may even be contributing to that summertime phenomenon, the Dead Zone.

McKay and Bullerjahn discovered the cold-loving algal plankton in Lake Erie by accident while onboard a Canadian Coast Guard icebreaker with New York Sea Grant researchers Michael Twiss and Steve Wilhelm in February 2007. “Apart from Professor David Chandler’s pioneering research in the late 1930s, to our knowledge there had been little done to study Lake Erie, its microbiology, and plankton in the winter months,” McKay says.

“Our plan was to go, do some sampling, and see what was out there. We had no expectations of what we would find.” What they found were pockets of brownishlooking water, some the size of swimming pools and some that stretched for kilometers. At first they suspected it might be stirred-up sediment, but their testing proved otherwise.

“I think a lot of people assume the lake is dormant in the winter,” Bullerjahn surmises. “As biologists, we knew that wouldn’t be true, but we were not prepared for the outcome: large accumulations of healthy diatoms under the ice, causing the ice to look brown.” It turned out that 80% to 90% of the biomass in those discolored water samples was Aulacoseira islandica, a psychrophilic, or cold-adapted, diatom that can survive in low light and seemingly disappears when spring rolls around.

“They don’t seem to be present once the water warms up,” McKay explains. So, how might diatoms that thrive in the winter influence a Dead Zone that occurs in July and August? It all has to do with their life cycle.

The Aulacoseira appear to be able to maintain their position just below the surface of the ice, where they are able to absorb sunlight and multiply. What McKay and Bullerjahn want to know is what happens next. Are they eaten by zooplankton and other organisms? Or do they die and sink to the bottom of Lake Erie? “If it turns out that most of these diatoms end up on the lake floor, they would provide a large source of organic carbon for bacteria to decompose, which would consume oxygen,” McKay says. “If this decomposition happens mainly when the water warms up and stratifies—forming a warm upper layer and a cold lower layer in the summer months—and not during the frigid winter months, it has to be contributing to the Dead Zone.”

To test this theory, the group will use Sea Grant funding to collect data for the next two winters, including taking part in several more science cruises. In addition, Environment Canada will use its icebreaker to deploy sediment traps that will sit on the bottom of the lake during the coldest months of the year, which should help determine if the diatoms are indeed sinking to the bottom of the lake.

If the blooms are occurring because of high nutrient levels in the water, it would be essential to track and potentially limit the source of those nutrients. Other theories point to the zebra mussel invasion as the trigger for Aulacoseira’s growth because of the mussels’ ability to increase levels of dissolved silica, a nutrient needed in large amounts by the algae. Certainly, McKay and Bullerjahn and their newly discovered, winter-loving diatom are poised to shake up the traditional models that considered Lake Erie more or less dormant from November through March. Preliminary data should be available in Summer 2010.

Sunday, June 20, 2010

Grand Lake Ecosystem Experiment - Diatom

Testing to grow profitable lake algae
local picture
GRAND LAKE - Some professors and a local student at Bowling Green State University are experimenting with Grand Lake water to get a less harmful type of algae to grow so it can be harvested.
The experiment, a collaboration between BGSU, the city of Celina and Algaeventure Systems, Marysville, began about four weeks ago.
In March, Celina officials met with professors who are researching Lake Erie algae issues. Similar to Grand Lake, Lake Erie has blue-green algae that produces a potentially harmful toxin.
"They wondered if there was a way to influence the water so a strain of algae that doesn't make the toxin could be grown," Celina Planning and Community Development Director Kent Bryan said. "Naturally we were interested."
Bryan has been looking into the possibility of harvesting the lake's algae for biofuel production for a couple years, but the strain in Grand Lake won't work because it is low in lipids (oil).
Algae higher in lipids is better for producing products such as biofuels, bioplastics and animal feed, said Chad Hummell of Algaeventure Systems.
"We thought if we could manipulate the nutrient contents we could change the composition of the algal community to something less harmful," said George Bullerjahn, one of the biology professors working on the project. "We are proposing that if we increase the amount of silica in the water, we can get a friendlier algae called diatoms to grow and be less toxic."
Diatom algae is a good source of oil, which makes it a good source for biofuel and bioplastic production, he said.
Passers-by driving onto West Bank Road may have noticed one of the experiment sites marked as Grand Lake Ecosystem Experiment (GLEE).
Six tanks filled with lake water are tethered along Grand Lake near Big Bamboo's Dockside Grill. The containers have open tops covered with mesh to let air in and keep debris out.
Two of the tanks (control) contain untreated lake water, two contain lake water seeded with nitrates and two contain lake water seeded with silica and nitrates. Nitrates are found in runoff into the lake while silica is not, Bullerjahn said. Silica is a natural element found in rocks and quartz. Glass is made of silica, Bullerjahn said.
There also are six tanks containing the same amounts of lake water, nitrates and silica at the water treatment plant.
Samples are being taken from all 12 tanks twice a week and lab work is being conducted at the Celina Water Treatment Plant, BGSU and Heidelberg College. The tests are designed to show what types of algae is in the water and if the populations change based upon what is added.
Bullerjahn said the lake experiment site is a more natural setting because the containers are in the water with open tops. The advantage of having a duplicate set of tanks at the plant is they are not exposed and can be monitored and controlled more closely, he said. The containers at the plant also will show how sunlight may be a factor in algae growth, he said.
Bullerjahn said the team plans to run two identical, six-week experiments. The second should wrap up in late July or early August.
If the experiment shows a "friendlier" algae could be stimulated to grow, Algaeventure Systems might consider sectioning off small portions of the lake to harvest it, Bullerjahn said. It is still unknown what effect this might have on the blue-green algae.
Taking the water samples each week is Katrina Thomas, a junior at BGSU and a lifelong resident of St. Marys. Assisting her is Ben Beall, a post-doctorate fellow at BGSU who works with Bullerjahn, and professor Mike McKay.
Thomas said she has been aware of the lake's excess nutrient and algae issues for some time.
"I like to know what is going on and why," she said. "Since I live here, I'm glad I have a hand in helping it."
Local officials have known of Grand Lake's blue-green algae problem, but it was more of a nuisance. It colors the water green, causes slimy slicks on the surface and sometimes kills fish. The problem became an economic nightmare for the area last summer when the state issued a water quality advisory because of a toxin produced by the algae.
The advisory was lifted in April after toxin levels dropped, but a huge algae bloom Monday put the issue back in the spotlight. Excess nutrients that run off farmland is what feeds the blue-green algae.

Harvesting test set this summer:
Algaeventure Systems, Marysville, plans to test algae harvesting equipment in the lake this month.
The test will help determine the feasibility of removing algae from natural bodies of water to use as an energy source, said company spokesman Chad Hummell. The test also will help determine the feasibility of removing nutrients (phosphorous and nitrates) as a way to improve the lake's water quality, he said.
The company's specialty is making algae harvesting equipment. The company grows algae in 11-by-200-foot covered ponds at its Marysville facility, but it has done little work harvesting from natural water bodies, Hummell said.
"Green energies have been gaining popularity especially due to what's happening in the Gulf, but with Grand Lake we have to find a way to help remediate the lake, no matter what the source of the N and P is," Hummell said. "Drawing the algae out is a way to help do that."
Hummell said the lake's blue-green algae isn't conducive for biofuel or bioplastic production but it might be used as a biomass that can be burned to create electricity.
Hummell said removing algae and nutrients isn't the only answer, but just one piece of a larger plan to address the lake's water quality concerns.
"It not the silver bullet, but a thing that can work with all the other stuff going on and add up," he said.
- Nancy Allen

Red Tides - Florida

Red Tide Control and Mitigation Program

Pg 25

Biological control of Karenia brevi s toxicity

Georgia Institute of Technology, Julia Kubanek


Can other organisms break down red tide toxins? This study demonstrated that native Gulf
of Mexico phytoplankton species are capable of detoxifying waters containing red tide. The phytoplankton do not kill Karenia brevis cells, but they remove brevetoxin from the water column.


Growing concern over Florida red tide impacts has motivated researchers to understand how blooms work and how to lessen their effects. There are several forms of brevetoxin (PbTx) produced by Karenia brevis. Researchers at Georgia Institute of Technology have shown the amount of the most reduced 50-90% when competitive phytoplankton species are present. Further understanding how this process occurs is an important step towards developing a biological control for red tide toxicity.

Project goals

The main goals were to identify which phytoplankton competitors can degrade waterborne brevetoxins and to understand how this degradation occurs. Researchers aimed to determine whether adding live phytoplankton could be a natural biological control of Karenia brevis toxicity and whether this method could also benefit marine life.

Findings and accomplishments

Researchers learned that many phytoplankton competitors (across taxonomic groups, including
diatoms, cryptophytes, and dinoflagellates) can remove waterborne PbTx-2 (see Figure 1). Testing for removal of other brevetoxins by the diatom Skeletonema costatum showed that the detoxifying effect depends on the specific form of brevetoxin (for example, PbTx-2 and -1 were removed, but PbTx-3, -6, and -9 were not removed), suggesting that enzymes play a role in the removal of brevetoxins by competitors.

By adding brevetoxins to killed cultures of Skeletonema costatum and finding no loss of toxin,
researchers learned that live cells are required to remove brevetoxins from the water column, and that the toxin does not simply stick to cellular debris associated with the competitors. However, compounds (probably proteins) exuded by competitors are responsible for some toxin breakdown or removal.

Tests of how much Skeletonema costatum is needed to remove brevetoxins from the water showed that the quantity of competitor cells present has only a small impact on toxin removal. What is most important is the presence of competitor cells.

Experiments with marine invertebrates were also done to learn whether the effects of toxins on
marine life could also be reduced. Tests with brine shrimp (Artemia salina) showed that Skeletonema costatum reduced brevetoxins and removed all toxic effects on the brine shrimp at environmentally realistic concentrations. Tests with the sea anemone Aiptasia pallida included observing physical and behavioral responses as well as toxin levels. Results showed that Skeletonema costatum reduced, and in some cases completely protected against, the physiological damages of brevetoxin exposure.

Pg 26

The finding that Skeletonema costatum can reduce the toxic effects of brevetoxins on marine invertebrates supports using competitor phytoplankton species as control agents for Karenia brevis -- a mitigation strategy that not only will reduce waterborne brevetoxin levels but also could reduce negative impacts on ecosystems and marine wildlife.

Pg 31

Nutrient controls contributing to Karenia brevi s blooms in the Gulf of Mexico
University of South Florida, Jason Lenes

This project addresses one piece of the nutrient puzzle related to red tide. Researchers used computer models and experiments to show that increasing the amount of the nutrient silica in an ecosystem may favor the growth of more beneficial phytoplankton species rather than Karenia brevis.


Understanding how Florida red tide blooms start, grow, and maintain themselves is key to finding ways to stop or reduce their impacts. Trichodesmium, a nitrogen-fixing marine microorganism, and rotting fish killed by brevetoxins are primary food sources for Karenia brevis in the eastern Gulf of Mexico. These nutrient sources provide nitrogen and phosphorus but not silica. Large amounts of silica continually enter the Gulf from Florida’s rivers.

Although Karenia brevis does not need silica to grow, competitive and faster-growing organisms in the Gulf do. In the early stages of a bloom, organisms that are close to sources of silica may be able to compete more effectively for nutrients. This competition may help slow the growth of Karenia brevis and its potential prey.

Project goals

The project used laboratory and field experiments and computer simulation models to test the role of silica in Karenia brevis growth. Researchers wanted to know how different types and amounts of nutrients available to Karenia brevis may favor growth of more beneficial species. This information can help explain how Karenia brevis blooms grow and maintain themselves in the Gulf, and possibly how altering types and amounts of nutrients might be used to control blooms.

Pg 32

To see whether the presence of silica resulted in competition for food sources, two test cases were run: (1) normal initial silica concentrations and (2) elevated initial silica concentrations.

In case 1, a Karenia brevis bloom began in June (see Figure 1a) in response to the “new” nitrogen provided by Trichodesmium. In late July, the bloom reached levels that would kill fish, which gave it nutrients from the rotting fish. The maximum Karenia brevis level predicted by HABSIM in early October was similar to what was seen in the 2001 bloom. Case 2 showed a similar pattern, but the higher concentrations of silica led to an increase in diatoms, which decreased the predicted overall Karenia brevis concentration by about 50 percent (see Figure 1b).

Potential applications

The project results and HABSIM are great starting points for bloom prediction. Future experiments will test how nutrients with and without silica can alter natural shore samples and will help show competition and dominance among co-occurring Gulf of Mexico phytoplankton species. These results will be used to further test HABSIM as a prediction tool. If models continue to show that increases in silica reduce Karenia brevis concentrations, then ways of changing the nutrient regime to treat and reduce blooms can be considered.

Saturday, June 19, 2010

Gulf Oil Spill - Oil-eating microbes a possible solution

Oil-eating microbes a possible solution

Can naturally occurring, oil-eating microbes help clean the waters and shores of the Gulf of Mexico? Scientists, BP and government officials are moving toward trying it.


One scientist compares them to the yellow chompers in the Pac-Man video game -- hungry, single-minded little microbes fueled by the same fertilizer that farmers use on soybeans, gobbling hydrocarbons from the oily waters, marshes and shores of the Gulf of Mexico.

Can the naturally occurring microbes help clean up the oil spill?

Yes, experts say. At least in part, with some risk.

Officials are taking note. Gov. Charlie Crist on Thursday visited a Sarasota company that sells microbes that eat oil. BP says it's open to using them. And the federal government this week is contacting its pre-approved list of more than a dozen companies to see how quickly they can ramp up production.

Scientists call the process bioremediation.

``You take natural oil-eating microbes in the water and give them fertilizer to make them multiply and degrade the oil faster. Oil is a natural product. It's inherently biodegradable,'' said Terry Hazen, microbial ecologist in the Earth Sciences Division of the Lawrence Berkeley National Lab in California.

Oil-eating microbes -- with names like Alcanivorax borkumensis -- are some of the smallest living things on earth, but they can have a powerful impact. The bacteria occur naturally in water and, when they come in contact with oil, they eat it, producing the byproducts carbon dioxide and water.

When fertilized with nitrogen and phosphorus, they grow in size and multiply and their appetites become prodigious.


Still, scientists caution that bioremediation is only a partial solution. It's best used on sandy beaches and in salt marshes after the thickest oil has been removed by bulldozer and shovel. It's never been tried before in deep water or open ocean.

And it runs some risk of damaging the very waters it's meant to rescue. Some scientists say it may be better at times to let nature take its course.

Jay Grimes, a microbiologist at the University of Southern Mississippi, is a fan of the process: ``It could help a lot. It was used in the Alaska oil spill'' from the Exxon Valdez in 1989. ``It worked very well on the rocky shores.''

Bioremediation can't do the whole job, said Chris Reddy, marine chemist at Woods Hole Oceanographic Institution in Massachusetts.

``The idea that microbes can come in and clean house from A to Z is not likely,'' he said. ``What they can do -- on their own time -- is eat some compounds and play an important role in the cleanup.''

BP says it's looking into bioremediation. ``Potentially we could do it, but we would need approval from the EPA,'' spokesman Tristan Vanhegan said Wednesday. ``Typically it's not done until the oil has stopped flowing.''

The federal government is working on possible bioremediation efforts. The EPA has created a National Contingency Plan Product Schedule listing more than 20 biological agents approved for use in encouraging microbes to attack oil spills. And the USDA's Natural Resources Conservation Service is contacting the companies that make them to see how quickly they can ramp up production.

And there's yet another oil-eating product, called Munox, made by Osprey Biotechnics of Sarasota, that has interest from Florida officials. Munox isolates natural microbes from nature, ferments them and adds proprietary ingredients to turn them into a concentrated liquid form to spray on oil spills.

But there's a danger. Add too much fertilizer and you can create blooms of algae that use up all the oxygen in the surrounding water, creating ``dead zones.'' There's already a 6,000-square-mile dead zone in the Gulf off the mouth of the Mississippi River, created years ago by the same fertilizers washing down from upriver farms.

``It's pretty big and pretty scary,'' said Jim Spain, professor of environmental engineering at Georgia Tech.

As much as 20 million gallons of oil a year naturally seeps into the Gulf through tiny fissures in the seabed. Over time, microbes have evolved that eat the oil in the water -- enough so that all the seeping oil doesn't create a sheen.

But the huge BP spill has overwhelmed existing microbes. To grow enough in size and number to cope with the spill, they need nitrogen, phosphorous and iron.

``They're like Pac-Men -- their mouths are only so big,'' Reddy said.

Scientists differ over the success of past bioremediations.

In Alaska after the 1989 Exxon Valdez spill, clean-up crews spread nitrogen and phosphorus in liquid sprays and slow-release pellets on hundreds of miles of oil-coated rocks in Prince William Sound to quicken the action of natural microbes in eating the oil, says Ronald Atlas, a microbiologist at the University of Louisville who took part in the cleanup.

Atlas says, and a 1991 EPA after-action report confirms, that the fertilizer increased the degradation of the oil three- to five-fold, with no damage to the environment.

``The beaches became visually cleaner,'' the report said.


Terry Hazen, who studied the project, has a different conclusion. He says the bioremediation of the sound with phosphorous and nitrogen wrought severe long-term damage to its ecology.

``We took a low-nutrition environment and added lots of fertilizer,'' Hazen said. ``The phosphorous created nuisance algae.''

Bioremediation in the Gulf must be thoroughly studied and done carefully, the experts agree.

``There may be reason to use it where the oil is not degrading fast enough,'' Hazen said. ``In other cases, the best thing may be to do nothing.''

Scientists differ on whether fertilizing natural microbes can help degrade deep oil plumes as far as 3,300 feet beneath the surface of the Gulf. Georgia Tech's Spain said he fears fertilizing microbes at great depths might use up the tiny amounts of oxygen that exist there, creating even more oxygen-depleted dead zones.

Last week, Hazen and his team set out in boats to examine the plumes, taking 200 water samples in the Gulf. They found microbes already in existence and noted it might not be necessary to add fertilizer.

Grimes, the Mississippi biologist, believes microbes can help in salt marshes, where oil mixes with water and grass and can't be cleaned by bulldozers or shovels.

``The first year there's not much you can do do reverse damage to marine animals or plants in marshes,'' he said. ``But if you can speed biodegradation, you can hope the ecosystem will start to rebuild within four or five years.''

He added that it's important not to let wave action wash fertilizer into the water where it could create algae blooms.

Another potential problem is that when microbes eat oil, a byproduct is carbon dioxide -- a greenhouse gas.

In an area as large as the Gulf, could it be enough to hurt the ozone layer?

``We don't have that answer,'' Grimes said.