[Coral-List] coral and crude oil

Eugene Shinn eshinn at marine.usf.edu
Sun May 2 11:39:07 EDT 2010

Dear listers here is some information re the effects of crude oil on 
coral that may be of use at this crucial time.
     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 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 
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 where I 
exposed Florida staghorn and star coral directly to oil for one and a 
half 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 living 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 Masters candidate approached me to do 
similar experiments for a thesis project. In the laboratory at Fisher 
Island Station we totally submerged ten fragments of living Acropora 
cervicornis in Louisiana crude for 2 hrs. We then transported them 
(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 
and 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 not attention to the overlying layer of crude oil. 
After 24 hrs the fish was sacrificed and taken back to Texas A and 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 
     The lesson from this and other research was that if and when the 
oil from this spill reaches the Florida Keys the damage will be to 
limited mainly to mangrove shoreline habitats, sea birds, and 
beaches. Dive boat operations will likely be affected but it 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 living 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 east coast of the 
US 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 is 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, Hopefully this 
knowledge will relieve some tension and fear for the reefs as the 
floating oil nears Florida's coral reefs. Nevertheless be prepared 
for one heck of a mess at the shoreline before this is all over. Lets 
hope it is 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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