[Coral-List] Disaster in the Gulf and Coral Reefs
Eugene Shinn
eshinn at marine.usf.edu
Fri Apr 30 13:03:49 EDT 2010
With the developing oil disaster in the Gulf, I thought a few
comments regarding the effects of crude oil on coral reefs might be
healthful. Some of you know my background in the industry and my work
with API committees before 1974. In 1972, I was sent to Australia to
testify before the Great Barrier Reef Commission regarding effects of
drilling on coral reefs. I was concerned, so in preparation for the
trip I obtained 5 gallons of Louisiana sweet crude (the kind
presently blowing out off the Mississippi Delta) and traveled to the
Florida Keys to do some personal in-situ experimenting. Corals on the
Barrier Reef flats (including various species of staghorn coral) are
exposed to the air at low tide each day for more than one hour. Since
that is the length of time that corals there are likely to be exposed
directly to floating oil, I performed some crude experiments wherein
I exposed Florida staghorn and star coral directly to oil for 1_
hours. In these experiments, I placed large clear plastic bags
containing crude oil over live staghorn that was fixed to rods driven
into the bottom. At the same time, I placed plastic domes (skylights)
containing oil over the tops of small star coral heads for the same
length of time. The experiment was conducted in about 15 ft of water
off Tavernier Key. What I found, and described pictorially in the
1989 issue of Sea Frontiers, was truly surprising. Corals retracted
their polyps, but the oil would not stick to the coral because of its
mucus. When I removed the oil, there was no oil on the coral. Fifteen
days later, the corals were alive and appeared normal. While at the
hearings in Australia, I learned that another researcher wearing a
backpack garden sprayer had sprayed crude oil on the same exposed
corals at low tide every day for several days. His results were
similar to mine.
After joining the USGS, a Master's candidate approached me to do
similar experiments for a thesis project. In the laboratory at Fisher
Island Station, we totally submerged 10 fragments of living Acropora
cervicornis in Louisiana crude for 2 hours. We then transported the
fragments (in sea water) to the reef line off Virginia Key, Florida,
and placed them in concrete holders in 20 ft of water. When we
returned a week later, the corals were alive and appeared healthy.
The disappointed student decided not to continue that project.
In yet another experiment, students of Tom Bright from Texas A&M
University conducted an oil experiment on Carysfort Reef lighthouse
off Key Largo. A 20-gallon aquarium was filled with aerated seawater.
The aquarium contained two butterfly fish and some live A.
cervicornis branches. A layer of crude oil about one inch thick was
then floated over the coral and fish. Butterfly fish are known to
feed on live polyps, so the purpose of the experiment was to see if
various fractions of the oil would contaminate the coral and then be
transferred to the flesh of the fish. The fish did pick at the coral
and paid no attention to the overlying layer of crude oil. After 24
hours, the fish were sacrificed and taken back to Texas A&M to be
analyzed for oil components. I never heard the results and nothing
was published. I simply documented it all on 16-mm movie film.
The lesson from this and other research was that if and when the
oil from this spill reaches the Florida Keys, the damage would be
limited mainly to mangrove-shoreline habitats, sea birds, and
beaches. Dive-boat operations would likely be affected, but the spill
will not harm corals or reef fish. The crude, which will likely be in
the form of tar balls, will simply float over the areas of live
corals.
Under no circumstances should dispersants be used on an oil slick
in the vicinity of a coral reef. Dispersants soluabilize the oil and
allow it dissolve in the water and come in direct contact with coral
and fish. In addition, oil-containment booms should not be deployed
in the vicinity of coral reefs because of possible entanglement and
physical destruction. The history of oil spills is that clean-up
efforts, such as use of live steam, solvents, and digging, often do
more damage than the oil.
The best teacher is history. The Keys and the U.S. East Coast
were often awash in oil from torpedoed tankers during WWII, and there
have been numerous tanker spills and oil from bilge cleaning over the
past 50 years with no documented impact to Florida's coral reefs. An
exception is the disastrous onshore oil tank spill at Goleta Point,
Panama, in the early 1980s. The spill was at the landward end of a
lagoon that opened out to a coral reef being studied by personnel at
the adjacent Smithsonian Institution Marine Laboratory.
Unfortunately, surfactants were added to break up and soluabilize the
oil in an enclosed area with poor circulation with disastrous
results. Many reef-flat organisms and corals were killed. Richard
Dodge conducted extensive research on the effects of that spill,
which are well documented.
In the present case, by the time the spilled oil reaches the
Florida Keys (weeks), the more toxic aromatics components will have
evaporated, and bacterial breakdown will have reduced the oil to a
less toxic gooey mess that can foul beaches, mangroves, and affect
sea birds. It will not harm corals or reef fish. Nevertheless, expect
to see headlines stating, "Spill Threatens Coral Reefs," and similar
overblown claims. Be prepared for one heck of a mess at the shoreline
before this is all over. Let's hope it's over soon. Gene
--
No Rocks, No Water, No Ecosystem (EAS)
------------------------------------ -----------------------------------
E. A. Shinn, Courtesy Professor
University of South Florida
Marine Science Center (room 204)
140 Seventh Avenue South
St. Petersburg, FL 33701
<eshinn at marine.usf.edu>
Tel 727 553-1158----------------------------------
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