Large pile of the elkhorn coral Acropora palmata broken off from the reef crest and transported at least 100 feet landward from there to be deposited in the back reef lagoon. Photo taken on the south side of the Dredge Site.|
The first photo shows a large pile of the finger coral Porites that was broken up by the storm on the south side of the Dredge Site. Note the large fragments of the elkhorn coral (Acropora palmata) on the right. This was a healthy thicket of Porites prior to the storm.
The next photo shows what this area looked like before Mitch. The dense thicket of Porites is in the center of the photo.
According to local divers the fore-reef (which is seaward of the reef crest) was severely damaged by the storm from close to sea level down to a depth of about 40 feet. We were unable to survey the fore-reef on our visit, but we did see a videotape produced by the staff at the Hol Chan Marine Reserve that shows that most of the sponges and sea fans had been removed from this environment, and many of the clusters of the elkhorn coral Acropora palmata and the staghorn coral Acropora cervicornis here also were badly broken. Reports from local divers also indicated that whereas some of the canyons ("grooves" in geological terminology) had quite a lot of sand (10-15 feet) eroded from them, others had as much as 10-15 feet of sand deposited in them. All of the storm-induced damage to the total reef ecosystem occurred after a massive bleaching event that began in late summer and reached full proportions by early October. This bleaching is reported to have extended from the back-reef into the reef crest and as deep as 60 feet in the fore-reef. Bleaching is believed to occur as a result of higher than normal seawater temperatures, which forces the symbiotic algae ("zoonxanthellae") that live within coral tissue (which helps them build their calcium carbonate skeletons and colors them green) to leave. Seawater temperatures were quite high in August when we were there, and the sustained north wind at that time drove that hot water out over the reef. Some scientists believe that global warming is the culprit in ever-increasing reports of reef bleaching around the world.
This photo is an aerial view of the barrier reef and part of San Pedro Town, looking to the north, taken from an altitude of about 1800 feet. Thanks to TropicAir and Johnny Grief for the overflight. The Hol Chan cut is at the bottom of the photo; note the 9 boats (white streaks) anchored on the backside of the cut. The wedge of light color on the seafloor, seaward of the reef crest (line of breakers) and immediately north of the cut, is sand and gravel deposited by the storm in the fore-reef environment, at a depth of about 20-50 feet. A ribbon of newly-deposited sand and gravel extends north from there in the fore-reef. Note the wider ribbon of light colored sand and gravel behind the reef (left of center of the photo) that also was deposited recently by Mitch.
The most important lesson that we can learn from this storm is that humans canČt circumvent the forces of nature. In addition to geological changes, there will always be damage to human-built structures along the coast whenever severe storms hit. We can minimize damage in only one way -- by not building so many structures so close to the beach. All in all, however, Ambergris Caye and San Pedro Town were very lucky; the damage most certainly would have been worse if Hurricane Mitch had scored a direct hit. Most of the piers and dive shops were quickly being rebuilt in November, and much of the mess that Mitch left on the beaches also was being cleaned. By now IČm sure that industry in San Pedro is back to normal. The reef is still beautiful, and should be more so now that new coral growth has begun, and visibility was rapidly improving. For those of you wondering whether or not to make San Pedro and Ambergris Caye your next vacation stop ÷ book your reservations, your wonČt be disappointed.
Damage And Change Inflicted On Ambergris Caye And Surrounding Areas By Hurricane Mitch - by Dr. Sal Mazzullo, Dr. Collette Burke, Chellie S. Teal, MS, Krysti Weed, BS
Department of Geology, Wichita State University, Wichita, Kansas
E-mail address of senior author: firstname.lastname@example.org
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