JEFFREY BROWN: Next: back to the Gulf for a look at how scientists are tracking the oil spill's impact.
The government announced today it's working with university labs to deploy advanced sensor technology to study what's happening in the water.
One of those centers is based in Saint Petersburg, Florida.
"NewsHour" correspondent Tom Bearden reports on the work of researchers there.
TOM BEARDEN: The Weatherbird II may not be the biggest research vessel afloat, but scientists from the University of South Florida have been using it to investigate some of the deepest mysteries resulting from the Deepwater Horizon disaster.
It's in port in Saint Petersburg this week getting ready for another voyage to figure out what's happening to the oil, the fish, and the whole Gulf ecosystem.
When at sea, the ship deploys a variety of ocean monitoring devices and sensors. One of them looks a bit like a cruise missile, but without an engine. It's a programmable underwater glider. Each one costs more than $100,000.
JIM PATTEN, Center for Ocean Technology, University of South Florida: We have a fleet of five gliders. We have four of them that are depth-rated for 200 meters, and we have one that is depth rated for 1,000 meters.
They are equipped with a sensor suite that give us the capacity to measure temperature and salinity with depth. And one of the key sensors on these is what they call the CDOM sensors, which can be used as part of an analysis technique to determine the presence of hydrocarbons.
TOM BEARDEN: Since the well blew out, there have been a lot of pictures of the surface oil affecting the marshes, the beaches, and the birds. But there's been a lot of debate and discussion about the oil that people cannot see.
Oil is lighter than water, and one would expect it to rise to the surface. But, in this spill, some of it is staying underwater.
Chemical oceanographer Dr. David Hollander says, when the warm, highly pressurized oil emerges into the near freezing water, a remarkable transformation takes place.
DR. DAVID HOLLANDER, chemical oceanographer, University of South Florida: All to those combine together to sort of make it a fire hose shooting out very, very fine particles, atomizing the petroleum into micro- droplets, which will then re-coagulate or re-coalesce to form larger components of the oil, which then can rise.
A portion of those micro-droplets are entrained in the currents and are transported away. And those are the ones that we think are making up the -- the subsurface petroleum.
TOM BEARDEN: The Weatherbird II has tracked the underwater particles up to 40 miles from the wellhead, but scientists don't yet understand much about why they behave the way they do.
DR. DAVID HOLLANDER: Are these isolated layers that have no connection, or whether there is sort of a stair step between these layers, what is the difference in the chemistry of these layers, that is for the information that we are discovering on the next cruise that we go out on the Weatherbird in the middle of July.
TOM BEARDEN: Dr. Ernst Peebles, the principal investigator on an earlier cruise, says these so called plumes are more like clouds than a concentrated river of oil beneath the surface.
DR. ERNST PEEBLES, College of Marine Science, University of South Florida: Plumes in general make people think of something like a volcano or an active, spewing mass of black oil, when, in fact, what we found was layers of microscopic droplets of oil.
TOM BEARDEN: Things you can't see with the naked eye?
DR. ERNST PEEBLES: That is right. They are much smaller than you can detect with the naked eye. We had optical instruments on board that detected these droplets very readily. They had no problem at all saying that there was oil in this clear water.
TOM BEARDEN: If it is clear and you can't see it, what is the risk? What is the problem with that?
DR. ERNST PEEBLES: Toxic properties. It can either create a direct contact type of toxicity. Or there is a very low concentration of dissolved hydrocarbon associated with these.
TOM BEARDEN: Both Peebles and Hollander are worried about what will happen when very small organisms ingest these microscopic tar balls, and how the entire deepwater food chain might be affected by extended exposure to oil.
DR. DAVID HOLLANDER: Some of these continental shelf and slope environments are the home to some really, really important marine protected areas, as well as some of the nursery grounds and larval fishing areas -- fish areas for some of the most important recreational and commercial fish stock. So, the impact could be severe. And it may not occur in this year's life cycle. It may occur in four years' life cycles from now.
TOM BEARDEN: Another big question these scientists are investigating is where the spill might go.
Dr. Robert Weisberg has worked with other scientists and government agencies to put together a series of computer models to track the oil.
DR. ROBERT WEISBERG, College of Marine Science, University of South Florida: If we can model how the water moves as accurately as possible, we can model how the oil sitting on top of the water is moving as accurately as possible.
TOM BEARDEN: One of the things Weisberg is studying is the loop current, the way the water flows from the Yucatan Peninsula in Mexico through the Florida Strait.
Frequently, that current spawns an eddy, a sort of slowly rotating whirlpool. Weisberg says, in the past, the eddy current has gone as far west as the well site. If it does so again, it could push a considerable amount of oil through the strait, into the Gulf Stream, and then up the East Coast.
DR. ROBERT WEISBERG: And, so, it is hard to predict -- in fact, it is impossible to predict exactly how the loop current and its eddy will behave over the short term. And it is hard to predict what the winds will do too far out. And so that is why we have to run these models on a daily basis, update them, and just watch and see what happens.
TOM BEARDEN: Weisberg and other university scientists have undertaken a lot of this research on their own initiative, and Weisberg is frustrated that it's not better coordinated.
DR. ROBERT WEISBERG: But other people are looking at satellite images that we don't have available to us. There are a lot of active radar images that -- from which oil can also be gleaned. But we don't have access to those.
There are ships at sea. There are aircraft overflights, a lot of these things. And I would have hoped that by now, two months in, someone within Unified Command would have put all this together in a nice, neat data set and made it available, so that people like me or anybody else could use them. And that has not happened. So, that's been a big disappointment.
TOM BEARDEN: Despite the lack of coordination, scientists say much remains to be studied.
DR. ERNST PEEBLES: In the future, we hope to be looking more at the ecological effects of the spill. So, the whole idea about oil impacting known delicate ecosystems is really a new one. The toxicity studies that have been done in the lab do not replicate this scenario. We really have to start looking at this from the ground up.
TOM BEARDEN: Fourteen scientists will board the Weatherbird II in a few weeks and embark on another trip into the Gulf to gather more data on how the entire ecosystem is reacting to the oil.