[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 

     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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