Geology Reference
In-Depth Information
Fig. 12.4.
Impact of Hurricane Gilbert on a reef
on the western shelf off Cozumel Island.
A:
Pre-hurricane situation
. The
reef slope is densely covered by scleractinian corals (
Porites, Montastraea, Agaricia
), octocorals, and some yellow sponges
(in the foreground). The photograph was taken at a depth of about 15 m.
B:
Post-hurricane situation
after the reef destruction
by Gilbert. The photograph, taken on September, 18, 1989, almost exactly one year after the hurricane, shows the same
location as Fig. A. Almost all former reef builders have been removed or fragmented. The number of hard bottom areas has
dramatically increased. A part of the former reef area is now covered by coral debris (mainly
Porites
), gravel-sized rubble
and meter-sized coral blocks (in the background). Large areas of the slope are coated by sand-sized sediment reworked from
inter-reef terraces. This sand acted similar to sandblasting equipment, destroying the living reefs and scratching out newly
formed free hard bottom areas. Resettlement is weak except for thin cyanobacterial mats growing on a few coral blocks.
Photographs: Courtesy of G. Muckelbauer (Erlangen).
