Hurricane Mitch affects Glover's Reef, Belize

[Tom Bright]

MEMORANDUM TO: Mr. James Azueta, Marine Reserves Division, Belize Dept. of
Fisheries
FROM: Dr. Thomas Bright, Station Manager, Wildlife Conservation Society,
Glover's Reef Marine Research Station, Middle Caye, Belize
SUBJECT: Damage to Glover's Reef by Hurricane Mitch
DATE: Nov. 21, 1998

Dear James,

The eye of  Hurricane Mitch passed approximately 120 miles southeast of the
Glover's Reef Marine Reserve in late October, 1998. The wind was not high
enough at the reef to do serious damage itself. According to water marks on
the buildings on Middle Caye the sea level was up approximately  three feet
above normal at the reef during the storm. The north and east portions of
Glover's Reef were subjected to seas in excess of 20 feet in height for
several days.

Virtually all of the damage and modifications to the reefs, islands,
vegetation, and buildings was caused by a combination of severe wave action
and high water. Long Caye appears to have been most affected, whereas Middle
Caye was the least. Several buildings were washed away on all of the islands
at Glover's Reef except Middle Caye. Both of the small cayes (Fisherman's
and LaMont's) previously northwest of Long Caye are gone (reduced to a small
sand spit) and much of the sediment from them is apparently now part of a
new beach on Long Caye. All of the larger islands lost some shoreline along
the north and east shores (50 feet or more at Long Caye, three to five feet
at the more protected Middle Caye). Generally, the sand and rubble torn from
the shore was thrown over onto the island, increasing the size of adjacent
ramparts and the depth of sand behind them (up to five feet of new sand near
the eroded shore on Long Caye and six to 18 inches on Middle Caye).

Last week  (around Nov. 15) I examined the lagoonal patch reefs adjacent to
Middle Caye and the seaward forereef down to 25 feet for a half mile
northward of Middle Caye. Little or no hurricane-related damage was apparent
on the patch reefs in this protected area of the lagoon. Mechanical damage
to the upper forereef on the seaward side of the eastern barrier of  the
atoll was extensive. On that part of the forereef that I examined, I am
guessing that there was 60 to 75 % coral mortality (possibly more) due to
the storm. This is largely because the wave action dislodged a multitude of
coral heads and reefrocks and carried them onto the emergent topreef. The
previously discontinuous emergent part of the topreef next to Middle Caye on
the north became continuous for about a half mile and increased in width
from only a few feet to nearly 100 feet. The multiple tons of coral sand,
gravel and boulders to build this newly emergent topreef all came from the
adjacent forereef.

 Numerous newly-killed heads and pieces of the following corals were noticed
by me on the topreef following the storm: Acropora palmata, A. cervicornis,
Montastrea annularis (et al.), M. cavernosa, Dendrogyra cylindrus, Diploria
spp., Colpophyllia sp., Dichocoenia sp., Agaricia tenuifolia, A. spp.,
Porites astreoides, P. sp., Siderastrea spp., Millepora complanata, M.
alcicornis, Gorgonia spp., various alcyonarians. There were others but these
were the main "just-killed" taxa seen on the topreef.

Underwater, the upper forereef looks nothing like it used to. The remaining
heads of Agaricia tenuifolia and Millepora complanata which were previously
so conspicuous appear as if they had been beaten thoroughly with a club. All
the margins of the leafy colonies are chipped and broken off severely. What
is left looks sandblasted, with little living coral tissue left. Recently
broken pieces of Acropora palmata lie about. Those still standing are
abraded and have lost much of their tissue. I saw no remaining living
branches of Acropora cervicornis.  Montastrea  heads were still standing but
some were toppled over and many ended up on the topreef. Living alcyonarians
were very sparse compared to pre-storm conditions. It appears that the storm
waves acted to break, overturn, transport, and abrade reefrock and coral
colonies on the upper forereef. The abrasion process appears to have removed
much of the living coral and epibenthos that occupied the reef substratum
prior to the storm. The rock surface thus exposed has been colonized by a
pervasive cover of filamentous green algae, giving the entire upper forereef
a dominant green hue. Grazing and browsing fishes are much in evidence,
though not in greater numbers than previously, in my estimation. 

Remaining living coral tissue was still in a "bleached" condition. Some
recovery had occurred from the Sept.-Oct., 1998 mass bleaching event - but
not much. Most heads that originally bleached were still bleached at the
time of the storm, though gradual browning of many Montastrea heads was
evident. Therefore the storm damage was imposed on a reef coral population
in the initial stage of recovery from a recent mass bleaching event.
Unrelated to the storm, on the lagoonal patch reefs adjacent to Middle Caye,
I have noted some obvious mortality resulting from bleaching in Acropora
palmata, Porites porites and Millepora sp.

As yet, I have not examined the deeper forereef and "wall" off  Middle Caye
subsequent to the hurricane because I have been too busy with repairs on the
island. When I can, I will submit a further report. 

TOM BRIGHT
Dr. Thomas J. Bright, Station Manager
WILDLIFE CONSERVATION SOCIETY
Glover's Reef Marine Research Station
PO Box 2310
Belize City, Belize

Ph./Fax. 011-501-02-33855 (Belize City)
Ph. 011-501-05-22153 (Middle Caye)
E-mail <glover at btl.net>
Website <www.une.edu/glover/glovindx.html>