[Coral-List] Coral demise in Belize

[Eugene Shinn]

Coral demise in Belize

Here is another old coral story from before most readers were born that 
relates to the demise of Caribbean corals. Our USGS Fisher Island team 
conducted two long expeditions to Belize to conduct seismic profiles, 
core, and sample reef sediments. The first was in 1976. The second was 
roughly 1980. The first cruise required many months of waiting for USGS 
headquarters to obtain State Department approval of our cruise. We 
cruised from Miami on a 50 ft. trawler, “Sea Angel” captained by Roy 
Gaenslen. Our base in Belize was the Smithsonian Field Station on Carrie 
Bow Key. Unlike coral distribution in the Florida Keys we found A 
/cervicornis/ growing on shallow flats surrounding Mangrove islands. The 
reef flats have steep 45-degree margins rising up from lime mud bottom 
10 to 12 m below the surface. A. /cervicornis/ grew right up to the edge 
of Red Mangrove prop roots, which was very different from its 
distribution in the Florida Keys. We took push cores with 3-inch 
diameter aluminum tubes pounded in using a hydraulic jackhammer. Most 
cores contained several meters of fossil Staghorn coral essentially 
floating in lime sand and mud. It became clear that A. /cervicornis/ had 
been growing adjacent to mangroves for many years. We also cored reef 
spurs on the main reef tract using our rotary diver-operated coring device.

On our second cruise to the Belize reefs we found that all the A. 
/cervicornis/ had died. Its demise was in keeping with other 
observations throughout the Caribbean. At the time we did not know about 
ongoing Caribbean-wide coral demise nor did we know /Diadema/ urchins 
would soon perish throughout the Caribbean in 1983. It did later become 
clear that demise of Acroporid corals as well at the /Diadema/ urchins 
did happen during the same year. Until /Diadema/ and many coral died 
most of our observations were restricted mainly to the Florida Reef 
Tract where demise was blamed on 1) Sewage, 2) Aerial Mosquito spraying. 
3) Anchor damage, 4) Outboard motor exhausts, 5) Touching corals and 6) 
coral disease to name the main ones.Most reef researchers had not yet 
proposed climate change. Nevertheless, most of us were convinced human 
activity was somehow involved. Rapidly increasing human population in 
the Keys was considered to be behind it all. Many of us pointed toward 
rapidly increasing population and sewage injected to shallow depths into 
the water table as a likely cause. As time went on we learned more about 
reef demise throughout the Caribbean. The death of A. at San Salvador 
during 1983 was to us a turning point. We knew that island was far out 
in the Atlantic and surrounded by clear deep oceanic water. That was 
when we learned of Dr. Prospero’s record of annual dust flux in 
Barbados. His record showed 1983 to be the peak year of transport of 
dust from Northern Africa to the Caribbean. Dust being related to coral 
and urchin demise/disease seemed valid because it was also occurring 
around poorly populated islands and in some cases islands with no real 
human population. Coral demise around such place continues today. See 
recent observations of coral demise around small islands in the Turks 
and Caicos region.

Remember, the first observations of ongoing coral demise in the 
Caribbean began in the late 1970s and began peaking throughout the 
Caribbean back in 1983. We documented it in Belize after our first 
cruise in 1976 and 1980.

*References*:

Halley, R.B., Shinn, E.A., Hudson, J.H., Lidz, B., 1977, Recent and 
relict topography of Boo Bee Patch Reef, Belize: International Coral 
Reef Symposium, 3rd, Proceedings, Miami, Florida, v. 2, Geology, p. 29-36.

Shinn, E.A., Hudson, J.H., Halley, R.B., Lidz, B., Robbin, D.M., and 
Macintyre, I G., 1982,

Geology and sediment accumulation rates at Carrie Bow Cay, Belize, in 
Rutzler, K., and

Macintyre, I.G., eds., The Atlantic Barrier Reef Ecosystem at Carrie Bow 
Cay, Belize, I:

Structure and Communities: Smithsonian Contributions to the Marine 
Sciences, v. 12, p. 63-75.