Assessment of the Economic Impacts of Hurricane Gilbert on ...

CEP Technical Report No. 4occurrence after storms at Rio Bueno, Great River and o<strong>the</strong>r locations, but its ecologicaleffects are poorly documented. Damage to watersheds, due to loss <strong>of</strong> forest cover andsubsequent erosion, may prove to be <strong>of</strong> great importance to water quality andsedimentation in coastal environments <strong>of</strong> <strong>the</strong> next few years, because <strong>of</strong> <strong>the</strong> long-termnature <strong>of</strong> recovery <strong>of</strong> those upland environments.At <strong>the</strong> end <strong>of</strong> November 1988, <strong>the</strong> Port Authority contracted with <strong>the</strong> Royal NavyHydrographic Survey Ships HMS Beagle and Fawn to survey Kingston Harbour, to see ifstorm run-<strong>of</strong>f following <strong>the</strong> <strong>Hurricane</strong> had caused silting <strong>of</strong> <strong>the</strong> ship channel (Anon, 1988b). It was feared that any appreciable amount <strong>of</strong> silting, including tree debris and garbage,might cause obstructions to shipping. However, sonar traces showed no appreciablesilting since <strong>the</strong> previous survey conducted in about 1987 (Capt. P. Prawl, personalcommunication,). If a high sediment load had been brought to <strong>the</strong> Harbour from <strong>the</strong> RioCobre and o<strong>the</strong>r drainage channels, it is more likely that it would have been deposited inHunt's Bay.Salinity in Kingston Harbour was reduced after <strong>Hurricane</strong> <strong>Gilbert</strong> and remained lowerthan normal for several days, as noted by Alleng (Appendix 2).3.3 Coral ReefsThe best set <strong>of</strong> data on <strong>the</strong> ecological impacts <strong>of</strong> <strong>Hurricane</strong> <strong>Gilbert</strong> comes from <strong>the</strong>Discovery Bay Marine Laboratory; as researchers <strong>the</strong>re have long-studied monitoringstations on <strong>the</strong> reefs and had documented <strong>the</strong> effects <strong>of</strong> <strong>the</strong> previous hurricane (<strong>Hurricane</strong>Allen, 1980).Woodley (Appendix 9) reports that damage to <strong>the</strong> reefs in <strong>the</strong> Discovery Bay area wassevere. The level <strong>of</strong> damage was lower than that caused by <strong>Hurricane</strong> Allen, however,because <strong>the</strong> reef had not recovered to its pre-Allen structure and complexity by <strong>the</strong> time<strong>Gilbert</strong> struck. The types <strong>of</strong> damage were similar, and included breakage and smashing <strong>of</strong>branching and massive corals, scouring and abrasion by water-borne debris andredistribution <strong>of</strong> <strong>the</strong> debris, plus overthrow and breaking <strong>of</strong> sea-fans and o<strong>the</strong>r reeforganisms. Some degree <strong>of</strong> disturbance to fish territories and behaviour was noted. Theaeneral effect <strong>of</strong> <strong>Hurricane</strong> <strong>Gilbert</strong> has been to return <strong>the</strong> reefs to <strong>the</strong>ir immediate post-Allen condition.The effects <strong>of</strong> <strong>the</strong> <strong>Hurricane</strong> are likely to be felt in a loss <strong>of</strong> productivity, particularlyfisheries production due to habitat damage. The base structure <strong>of</strong> <strong>the</strong> reef has not beendisturbed to <strong>the</strong> same extent as <strong>the</strong> cover <strong>of</strong> living organisms, so structural values, such ascoastal protection, should not be reduced.As during <strong>the</strong> period following <strong>Hurricane</strong> Allen, reef recovery at Discovery Bay wasevident in a few weeks and is expected to continue. Recovery can be expected to be along-term process; pre-Allen ecology and productivity level had not been re-establishedby <strong>the</strong> time <strong>of</strong> <strong>Hurricane</strong> <strong>Gilbert</strong> (a period <strong>of</strong> 8 years). Fur<strong>the</strong>rmore, <strong>the</strong> reefs atPage 10