[Coral-List] Divers and corals
Alevizon, William Stephen
alevizonws at cofc.edu
Wed Apr 8 11:13:18 EDT 2015
Regarding Diver Education and Coral Damage:
Yes, as Medio (1997) and others have shown, proper dive briefings and diver education may - at least in some situations - have the capacity to lessen the per/diver damage done to reefs.
However, as Barker and Roberts (2004) pointed out, although “diver impacts can be reduced by education… high levels of damaged coral may be unavoidable if large numbers of divers use a reef.” In fact, their study (in the Caribbean) concluded that “Briefing alone had no effect on diver contact rates, or on the probability of a diver breaking living substrate.”
The need for reasonable limits to the number of divers allowed on a reef site has been pointed out by a number of studies”, to wit:
“We show here that recreational divers cause substantial direct (skeletal fracture, tissue abrasion) and indirect (deposition of sediment) damage to live stony corals in the Florida Keys ..Our study also reveals that the percent cover of live stony corals and the proportion of undamaged corals both decrease significantly with estimated rates of recreational diving on reefs in Key Largo. (Krieger and Chadwick 2013)
“If the tourism industry is to sustain itself in the Egyptian Red Sea, every management effort must be made to minimise the sources of stress on the coral reefs we can effectively control. This includes: not overfishing, minimising anchor, diver and blast fishing damage; not exceeding dive site carrying capacities, (etc.).” (Jameson et al. 2007)
“Above a certain threshold of use, estimated at between 4000–6000 dives per year, coral cover loss and coral colony damage levels may increase rapidly (Riegl and Velimirov, 1991; Dixon et al., 1993; Prior et al., 1995; Hawkins and Roberts, 1997).” (Source: Barker and Roberts 2004)
“Zones (At Dahab, South Sinai, Egypt) subject to intensive SCUBA diving showed a significantly higher number of broken and damaged corals and significantly lower coral cover. .. The results show a high negative impact of current SCUBA diving intensities on coral communities and coral condition. Reducing the number of dives per year, (etc.) are essential to conserve the ecological and the aesthetic qualities of these dive sites.” - Hasler and Ott (2008)
In short, the consensus of most researchers who have studied this issue appears to be that diver education alone is not sufficient to prevent substantial reef damage if the number of divers remains too high.
I think folks have been loathe to address this issue because of the obvious economic impacts it may cause to already established dive tour operators, but there is little doubt it is a major problem in some areas of the best developed reefs.
So, I ask again, is there any interest among other coral-listers to provide some tools that might bring greater public attention - and/or MPA management response - to this issue?
Seems to me that other efforts to restore highly damaged reefs may prove fruitless if 30,000 plus recreational dives per year occur at the restoration site. And the extent of recreational scuba diving in some of the best remaining examples of coral reefs in the Caribbean and Red Sea appears to be on an ever-increasing trajectory.
William S. Alevizon
Dept. of Biology
College of Charleston
58 Coming St.
Charleston, S.C. 29424
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