>>NARRATOR: On April 20, 2010, the "Deepwater Horizon" rig
exploded in the Gulf of Mexico, killing 11 workers
and setting off the largest accidental marine oil spill
in the history of the petroleum industry.
>>We haven't had an oil spill of this magnitude at this depth
and in this environment.
>>This was a systematic failure on the part of BP,
the industry in general,
and of the government regulatory regime.
>>NARRATOR: Over the course of nearly three months,
roughly 4.9 million barrels of South Louisiana crude
gushed out of the Macondo well and into the Gulf of Mexico.
>>It was beyond my worst fears.
It was something I hope I never see again.
>>NARRATOR: The Macondo wellhead was located
at 5,000 feet beneath the water's surface,
discharging large amounts of oil and gas
under enormous pressure.
>>Most other spills are associated with a surface breach
from a tanker.
The oil sits on top of the water.
This was a completely different situation.
This was the first deepwater blowout.
>>NARRATOR: 2.9 million gallons
of the chemical dispersant Corexit
were applied at the surface and near the wellhead
to break up the oil and keep it from soiling sensitive marshes.
>>Dispersants were a novel concept
in terms of using them subsurface.
There's a great amount of angst, not only in the public,
but among the federal agencies-- what are the limits of this?
Is this a good or bad thing?
>>I don't think anybody knows what the answer to that is.
I understand why the heads of agencies made the decision
to use the Corexit.
They were trying to avert a worsening condition
on the seashore,
in the sensitive nursery areas and the estuaries.
By making that decision,
they made the conditions worse offshore and at depth.
It was a no-win situation.
>>Trying to understand the balance
of those pluses and minuses in the long term
is clearly something that we have to find out.
>>NARRATOR: Opinions on the fate of the oil vary widely.
It is estimated that anywhere between 13% to 60% of the oil
remains in the Gulf of Mexico,
potentially affecting ecosystem health for years to come.
What will the long-term impacts be?
How long until the true extent of this disaster will be known?
>>Major funding for this program
was provided by the Batchelor Foundation,
encouraging people to preserve and protect
America's underwater resources.
>>NARRATOR: The catastrophic oil spill in the Gulf of Mexico
may no longer make headline news...
...but the response to the disaster is far from over.
Scientists from the government, academia,
and independent research institutions
continue to study the impact of the spill.
Among them is the faculty of the College of Marine Science
at the University of South Florida,
who became involved early on.
>>We had research vessels sitting at the dock.
We had personnel that had expertise in various areas
related to the spill, and so we felt that we needed to react.
>>NARRATOR: The USF College of Marine Science,
located in St. Petersburg, Florida, is the home base
for the Florida Institute of Oceanography's
research vessel Weatherbird II.
>>We were among the first vessels that were directly
in the oil spill, and we worked closely
with the federal government and with the state.
And we did it for several reasons, because, you know,
we felt like it was our responsibility.
We are a public institution.
We are here to serve the citizens of Florida,
and there was tremendous concern about what this will do
to our economy, to our tourism, which has been a big issue.
>>NARRATOR: Prior to the Weatherbird's
first research cruise in May of 2010,
a group of local researchers and faculty members
at the College of Marine Science
gathered to come up with a strategy.
>>We had a long discussion
about what would be the optimum sampling plan.
>>We had a couple of reasons
for expecting there to be a subsurface layer of oil.
One is some experimentation that was done
that indicated the majority of the oil released at depth,
at tremendous pressure, will not make it to the surface.
The pure physics of having very small droplets of oil--
which form naturally,
but they're also created intentionally
by dispersants such as Corexit--
those oil droplets have a very hard time
fighting against the resistance of the water on their way up,
and they end up being stationary.
>>NARRATOR: The USF scientists also knew
that shortly after the spill, a different group of researchers
working from the research vessel "Pelican"
had discovered an undersea hydrocarbon plume
to the southwest of the "Deepwater Horizon" drill site.
>>And that clicked for us,
especially with our circulation models that suggested
both a trajectory to the southwest,
but also to the northeast in the direction
of the continental slope and shelf of Florida.
>>So that narrowed things down very much,
to the point where we could look at the charts
and pick a place and say,
"This is likely to have oil at it."
We also picked areas that we thought would not have oil
for comparison.
>>We wanted to cover areas
that were of more intrinsic importance
to the state of Florida, as well as to cover regions
that other investigators weren't covering.
>>So we had a number of stations selected
at different distances from the wellhead
at different depths that were designed
to intercept any unseen oil moving toward the state.
>>NARRATOR: Once at sea,
it didn't take the researchers very long
to find subsurface oil.
>>Finding it, we thought, might be like a needle in a haystack.
But we found the oil within a few days.
>>It was a thick plume.
We were able to recognize two components--
one was at 400 meters that spanned about 100 feet thick,
and the other one was located
between 1,000 and 1,200 meters water depth,
which was essentially the bigger plume,
and that extended for upwards of 600 feet.
We were able to see these features in the subsurface
simply using a fish finder.
>>NARRATOR: Once back in the lab, Dr. Hollander and his team
ran chemical tests to confirm the plume was made up of oil.
Next, they matched, or fingerprinted, the plume
to the oil released by the ill-fated Macondo wellhead.
And the research didn't end there.
Since May of 2010,
the scientists have made repeated trips to the area.
While at sea, experts use a number of instruments
to collect data that might provide clues
on the environmental impacts of the oil spill.
Water samples are collected
using a device called a Rosette sampler.
>>A Rosette sampler has various bottles
that we can trigger at different depths.
And the way we decide what depths to trigger at is based
on sensors which are attached to the Rosette Sampler.
There's sensors for fluorescence, temperature,
depth, and also light-scatter,
and the light-scatter is a crude indication
of where there might be oil droplets.
>>The data from the sensors is retrieved back
through an electronic cable so that, on the ship,
we can see the data in real time.
>>NARRATOR: The scientists collect water samples
at standard depths, as well as in areas
where they observe some unusual features.
>>All right, could you bring her up to 800?
>>NARRATOR: The water samples collected are then used
for various analyses.
One technique can quickly detect the presence of hydrocarbons
in the water.
>>The technique is based on the fluorescence properties
of some chemical compounds.
What we do is we shine light of different energies on a sample,
and we collect all the emission at different wavelengths.
This gives us a three-dimensional picture
of the total fluorescence of the water in our sample.
>>So at this characteristic level here,
which is in the ultraviolet range
that's still below the detection level of the human eye,
that's a telltale sign of a petroleum signature
in the water.
>>NARRATOR: Samples that test positive
for hydrocarbon presence
are analyzed further and fingerprinted
to see if they are from the "Deepwater Horizon" spill site.
Other USF researchers along on the cruises
analyze water samples from the same sites
to see if they detect toxicity.
To do so, they use two different tests, or assays.
>>So for this assay, we are using a living organism,
a type of phytoplankton called dinoflagellate, as an indicator
whether or not there is something harmful in the water,
something that will negatively affect its metabolism.
So these dinoflagellates bioluminesce, or they glow,
and produce light as part of their natural metabolism.
And when they are stressed,
they will produce a lower level of light.
If there is a decreased light emitted,
there is something present in the environment
that is making them unhappy,
whether it be hydrocarbons or something else.
Essentially, we are looking for a correlation
between the toxicity data we've come up with
and data collected by scientists
that shows the presence of hydrocarbons.
So if we can correlate toxicity
with the presence of hydrocarbons,
that would provide evidence
for a biological effect in the environment.
>>NARRATOR: The second test, or assay, uses a bacterium
instead of phytoplankton to search for toxicity.
>>No one organism reacts to all the toxicants.
What we found was that the bacterial assay
was more sensitive to oil.
The dinoflagellate assay was more sensitive to the Corexit.
>>NARRATOR: These tests show,
if there is an acute toxicity present,
that could have an immediate impact on the ecosystem.
Scientists are also very concerned about the impact
that low-level, long-term exposure could have
on marine species and ecosystem health.
>>The chronic toxicity, the sub-acute toxicity
we haven't measured,
and we don't know what the impact of that's going to be
on the food chain, on fisheries,
and the health of the Gulf of Mexico.
>>The analogy is you can stick your nose into a bucket of paint
and you can sniff for a minute and get a headache,
a raging headache,
or you can paint your room and sleep in the room overnight
and wake up with the same headache.
So you can have a lower concentration
in the surrounding environment
but be exposed to it for a longer period of time,
giving the same toxic response.
>>NARRATOR: Another toxicity assay
looks at the potential of toxins to cause DNA mutations.
Of the water samples collected in August 2010,
about half were genetically toxic.
Tests conducted as recently as February 2011
continued to find genetically toxic samples.
>>And that means mutagenic,
or the capability to damage DNA and cause mutations,
and mutations can lead to cancer
and other bad effects in marine life.
And the other thing about DNA-damaging agents is that
it becomes a heritable trait.
If there's a mutation that's caused,
it can be permanently changed
in that particular breed stock or organism,
so we're very concerned about those types of toxicities.
One of the most susceptible to genetic toxic materials
are larvae.
And these are organisms that are just rapidly growing,
rapidly dividing, synthesizing a lot of DNA.
Now, the problem is that
the larvae won't turn up to be adult fish
for maybe three or four years,
so we might not really see the genetic impact
for a couple years,
and this might manifest itself in any number of features.
>>NARRATOR: Another group of USF scientists
is focusing their research on the impact the spill is having
on the bottom of the food chain.
>>The part of the food web that our group is targeting
is the lower end of the food web,
which includes the small microscopic plants and animals.
>>NARRATOR: Those microscopic plants and animals
are known as plankton.
>>Which means small organisms adrift with current.
Phytoplankton are the microscopic plants
that are unicellular plant life.
The zooplankton are the small, microscopic animals.
They range in size from microscopic,
which are the same size as the plants,
to individuals like small fish larvae, for example,
that you can see with the naked eye.
And we do a variety of different analyses
to determine what the composition is
of the phytoplankton and micro-zooplankton,
how many are there,
and how that changes through time.
And so what we're trying to observe is any differences
from a normal, natural variability.
>>NARRATOR: Observing such potential changes
is a bit of a challenge for scientists.
>>The Gulf of Mexico has been understudied,
so we didn't have really good baselines for comparison.
>>It's a very complicated system.
I always say the Gulf of Mexico
used to be the Rodney Dangerfield of oceans--
it never got any respect.
>>We need a lot more attention paid to establishing
these baselines of all types so we know what normal is.
>>If we had had years of data to this point where we knew
what the natural variability was over space and between,
you know, week to week, month to month, year to year,
we would be able to determine much more accurately
what the effects of the BP oil spill were.
>>NARRATOR: Despite some of the uncertainties,
scientists say they have observed a change
in the abundance and health of plankton,
and they expect to see continued changes over the next few years.
An increased mortality of plankton
could have serious implications for the entire food web.
>>We all fear what we call regime shifts,
when you have a large-scale change
in the dominant animals of your ecosystem.
It's very stubborn-- once it switches over to this new order,
it doesn't go back.
And so that would affect fishermen and cultures
all around the Gulf of Mexico
if all of a sudden a certain species of animal
that's been harvested for generations
has been replaced by another one.
>>I'm very concerned about things like
Atlantic bluefin tuna,
which a large fraction of the stock spawns in the area
where there was oil in the water.
>>And so that's a depleted stock as it is,
and so any factor that might reduce the number of animals
that might recruit to the population is of concern.
One of the things that's kind of a truism
of these big environmental events like oil spills is that
we need to expect the unexpected,
that there may, in fact, be these sub-lethal effects
that will only reveal themselves over time.
And we certainly saw that with "Exxon Valdez,"
and it's very likely that we'll see that here.
>>In the case of the "Exxon Valdez," four years went by
and the local herring stock was reopened for fishing,
and there was an immediate collapse in that fishery,
and that stock has not recovered since, and decades have passed.
>>NARRATOR: To determine the impact
the Gulf oil spill is having on fish stocks,
USF researchers are using an innovative method.
>>We're looking at the chemistry of otoliths.
Otoliths are ear bones that occur in the fish's head.
They're laid down in layers like an onion or tree rings,
and they incorporate the chemistry
of the water around them.
So you end up with a permanent record
of the history of the water that the fish was swimming in.
So to get that record out of the otolith,
we cut very thin sections out the middle of the otolith.
And then we polish those thin sections,
mount them on a slide, bring them to this machine,
and it has a state of the art laser
that is used to sample the different types of elements
that are recorded in the rings.
So if this fish were exposed to the oil spill,
you would see unique elements showing up in this transect.
So what we're looking for is,
number one, whether or not the fish was exposed
and, number two, whether or not the fish
experienced slower growth rate after it was exposed.
Slower growth rate in fish
generally translates into higher death rates.
So growth rate is not a trivial thing.
If we see that there was a reduction in growth rate
associated with exposure to the oil,
then that means something negative
is likely to be influencing the population.
We have a lot of samples of important recreational
and commercial species, including red snapper.
We have large predators.
We have small fish from the deep ocean
that people generally never see,
even if you spend your entire life on the Gulf,
things that we've trawled up
from the very deep part of the Gulf of Mexico.
So we have a comprehensive spectrum of species
that we'll be looking at.
>>NARRATOR: Studies suggest
that the oil in the water column is diluting
and some of its components are being broken down by microbes.
As more time passes, experts say it is becoming more difficult
to find traces of oil in their water samples.
>>The one place that still seems to be at potential risk
is the sedimentary environment,
both in the shallow but also in the deep marine system,
where the plume was, and in that region.
>>NARRATOR: To study the sediments,
experts collect samples with a device called a multicore.
>>There's a central column that has eight separate cores
that are set up that, when the device hits the sediment floor,
that main column impales itself into the sedimentary system,
closing, then, these vacuum-tight seals.
And then the activated sample pulls up,
a bottom arm swings underneath the core
and traps the core material inside
and brings it to the surface.
>>Depth is at 1,002 meters.
>>NARRATOR: Sediment samples are cut into thin slices
and spun in a centrifuge to separate the water from the mud.
This water, called pore water, is then analyzed for toxicity
and the presence of hydrocarbons.
>>This is a shape and a region
that's characteristic of petroleum.
We do need to do further analyses to say, "Oh, this is...
This is exactly one compound or another compound,"
and I'm in the process of doing that right now.
We've got some PAH standards.
PAH stands for polycyclic aromatic hydrocarbons,
and those are some of the most toxic compounds
that are in the petroleum mixture.
So what I'll do is I'll analyze those known standards,
and I'll be able to compare those to what I've seen
in the natural environment.
>>NARRATOR: PAHs are not only
some of the most toxic components of oil,
but they also take a long time to break down.
To date, USF scientists have found that pore water samples
from the sediment cores have tested positive for toxicity,
as well as the presence of hydrocarbons.
Many of those samples were taken in an area
known as the De Soto Canyon.
>>We knew from prior history that
that was a very important area for fisheries.
Canyons can also focus the downward flux of material,
as well.
So we anticipated that that might be an area
where we will also see an impact on the seafloor.
>>The sedimentation rates
in those areas in the De Soto Canyon
is about 0.3 millimeters per year-- 0.3--
so in three years, you get one millimeter.
That's under normal conditions.
What we're recognizing is that the sedimentation rate
has increased by about an order of magnitude.
So now we're looking at three to ten millimeters per year,
so a significant increase in sedimentation rate.
And the question is why?
And so there are a number of hypotheses.
The most prevalent one is the blizzard hypothesis,
and that is that the oil droplets,
maybe with the addition of the dispersants,
has lent itself to a very sticky type material
that aggregates other biological material,
and it ballasts it so that it eventually sinks.
And if there's enough of this,
you can actually smother the habitat below.
>>NARRATOR: Another theory on how the sediments
and marine life on the bottom of the sea may have been impacted
is known as the bathtub ring hypothesis.
>>The plume, as it impinges on the continental slope,
would leave a bathtub ring of petroleum products.
>>NARRATOR: In some areas, the small creatures that live
on the bottom of the ocean appear impaired or dead,
and scientists say more research needs to be done
to understand what is happening to the ecosystem.
Past oil spills, such as the "Exxon Valdez" in Alaska
and the Ixtoc spill in the southern Gulf of Mexico
have shown that toxic oil
can persist in the environment for decades.
>>The Gulf of Mexico is
one of the three largest oil provenances in the world.
Oil drilling, oil and gas exploration
in the Gulf of Mexico is here to stay.
>>We really need to have this well thought out
in terms of different scenarios,
and that can only occur if you've got research
that's relevant to the different problems that might occur.
We need to actually make some serious investments in this
so that the next time around-- and there will be a next time--
that we're not sort of offering platitudes
as opposed to actually having
hard quantitative information available.
>>NARRATOR: Many questions remain
about the long-term impacts of this oil spill.
Researchers from the University of South Florida
and many other institutions are doing what they can
to better understand the full implications of this disaster.
>>A lot of people are working very hard,
doing methodical tasks,
and often it's not until later that you realize
the significance of what you've found.
It'll take many years before we understand the impact,
and it'll take even longer
before we can put the impact into context.
Putting the spill into context
is definitely something that will take decades.
>>Major funding for this program
was provided by the Batchelor Foundation,
encouraging people to preserve and protect
America's underwater resources.