[Coral-List] Coral demise in Belize
Eugene Shinn
eugeneshinn at mail.usf.edu
Fri Jul 23 20:56:12 UTC 2021
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.
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