[Coral-List] Effects of nuclear testing on coral reefs

Eugene Shinn eugeneshinn at mail.usf.edu
Thu Jul 20 12:58:58 EDT 2017

I read the papers cited in Maria Beger’s posting and the one mentioned 
by Peter Sale with great interest. The conclusion confirms our 
observations at Enewetak in 1984.

First some background and why we were there. Our mission was to 
determine the size of nuclear craters created at the time of the event 
rather than the size one observes today. It was known that the submarine 
craters began enlarging and deepening immediately after creation. Such 
enlargement is less likely to occur with craters made by bombs on dry 
land.Why was this important? In the early 1980s congress was arguing 
over a proposed nuclear defense system called the MX Missile Program. 
Should we have ballistic missiles on moving trains to hide their 
locations from the enemy or put missiles in hardened silos? If in silos 
what should the spacing between silos be?No one knew the exact diameter 
of a crater made by a 10-megaton bomb. We could not do surface testing 
to find out. However, the US had tested these size bombs (devices) on 
atolls in the Marshall Islands. Unfortunately the present craters had 
increased in size due to compaction and dewatering than that produced at 
the instant of detonation. As geologists with the USGS our mission was 
to do geological detective work and determine crater size at the instant 
of what the Defense Nuclear agency called “the event.” That would in 
theory provided the knowledge of spacing needed for MX missile silos. We 
were very successful and were also told we could pursue any other 
geological or biological process of interest we thought important---and 
we did as described below.

All of us were impressed at the variety and abundance of corals and fish 
as well as the lack of residual radioactivity. A general cleanup of 
radioactive material had already been conducted and placed under a 
cement dome covering a crater on one of the islands. Everything we 
collected was checked for radioactivity and revealed safe levels. A 
major surprise was that growth rings in live half meter high /Porities/ 
head corals growing near the lip of Koa crater revealed they recruited 
and began growing in 1958, the same year the crater was created.A large 
2-meter-high /Porities/ head about 1 km from Oak crater created by a 
9-megaton device was also cored. The Geiger counter revealed low-level 
activity in the coral band that formed the year of the shot. Its growth 
rate had not been affected and growth rates afterwards matched growth 
rate before the atomic test.Fish and especially sharks were abundant and 
aggressive. We concluded that the reef (except within the huge craters) 
was minimally affected. Significantly the human population had been 
excluded from the atoll (as it was at Bikini) and there had been no 
fishing conducted there since the testing. This concurs with the 
observations at Bikini as reported on the coral-list.

Before going to Enewetak I had a brief conversation with James Stewart 
the long time dive master at Scripts who recently passed away at age 89. 
He told me he had dived in the hydrogen bomb crater known as Koa crater 
just 3-days after the blast. I felt relieved when I found myself diving 
in that same crater 26 years later.Gene


No Rocks, No Water, No Ecosystem (EAS)
------------------------------------ -----------------------------------
E. A. Shinn, Courtesy Professor
University of South Florida
College of Marine Science Room 221A
140 Seventh Avenue South
St. Petersburg, FL 33701
<eugeneshinn at mail.usf.edu>
Tel 727 553-1158
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