888

Conservation Biology, Pages 888–897
Volume 13, No. 4, August 1999
Effects of Recreational Scuba Diving on Caribbean
Coral and Fish Communities

JULIE P. HAWKINS,*§ CALLUM M. ROBERTS,* TOM VAN’T HOF,† KALLI DE MEYER,‡
JAMIE TRATALOS,* AND CHLOE ALDAM*

*Environment Department, University of York, Heslington, York YO1 5DD, United Kingdom
†Marine & Coastal Resource Management, The Bottom, Saba, Netherlands Antilles
‡Bonaire Marine Park, PO Box 368, Bonaire, Netherlands Antilles

Abstract:

Scuba diving on coral reefs is an increasingly lucrative element of tourism in the tropics, but divers
can damage the reefs on which tourism depends. By studying the effects of diving we can determine what
level of use is justifiable in balancing objectives of economic gain and conservation. Off the Caribbean island
of Bonaire we compared coral and fish communities between undived reserves and environmentally similar
dive sites where maximum use reached 6000 dives per site per year. At these levels of diving, direct physical
damage to reefs was relatively minor. There were more loose fragments of living coral in dive sites than re-
serves and more abraded coral in high- than low-use areas. Diving had no significant effect on reef fish com-
munities. Between 1991 and 1994, diving intensity increased 70% and coral cover declined in two of three
dive sites and in all three reserves, suggesting a background stress unrelated to tourism. There was a signifi-
cant decline in the proportion of old colonies of massive coral species within dive sites (19.2% loss), compared
to a smaller loss in reserves (6.7%). Branching corals increased by 8.2% in dive sites, compared with 2.2% in
reserves. Despite close management of reefs, diving is changing the character of Bonaire’s reefs by allowing
branching corals to increase at the expense of large, massive colonies. The impact of background stresses on
massive corals seems to have been greater in the presence of diving. Other studies have linked disease infec-
tion to coral tissue damage, and the higher rates of abrasion we recorded in dived sites could have rendered
corals there more susceptible to disease, thus mediating the decline of massive corals. Our study shows that
even relatively low levels of diving can have pronounced effects manifested in shifts in dominance patterns
rather than loss of overall coral cover. Bonaire’s reefs have among the highest coral cover and greatest repre-
sentation of ancient coral colonies of reefs anywhere in the Caribbean. Conserving the character of these reefs
may require tighter controls on diving intensity.

Efectos del Buceo Recreacional en Comunidades de Coral y Peces del Caribe

Resumen:

El buceo con tanques en arrecífes de coral es un elemento crecientemente lucrativo del turismo en
los trópicos; sin embargo, los buzos pueden dañar los arrefices de los cuales el turismo depende. Al estudiar
los efectos del buceo podemos determinar que nivel de uso es justificable al balancear objetivos económicos y
de conservación. En las afueras de la isla Caribeña de Bonaire comparamos comundades de corales y peces
entre reservas sin buceo y sitios ambientalmente similares con buceo y en los cuales el uso máximo alcanza
los 6,000 buceadas por sitio por año. A estos niveles de buceo, el daño fisico a los arrecifes fué relativamente
bajo. Existiéron más fragmentos sueltos de coral vivo en sitios de buceo que en las reservas y más coral le-
sionado en áreas de mucho uso que en las de poco uso. El buceo no tuvo un efecto significativo en las com-
munidades de peces de arrecífe. Entre 1991 y 1994 la intensidad del buceo se incrementó un 70% y la cober-
tura de coral disminuyó en dos de los tres sitios de buceo así como en las tres reservas, sugiriendo un estrés de
fondo no relacionado con el turismo. Existió un declive significativo en la proporción de colonias viejas de es-
pecies masivas de coral dentro de los sitios de buceo (pérdida de 19.2%) comparado con una pérdida menor
en las reservas (6.7%). Los corales de ramas se incrementaron en un 8.2% en sitios de buceo comparado con

§

email cr10@york.ac.uk
Paper submitted November 5, 1997; revised manuscript accepted November 11, 1998.

Conservation Biology
Volume 13, No. 4, August 1999

Hawkins et al. Scuba-Diving Effects on Coral and Fish

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un 2.2% en las reservas. A pesar del manejo estricto de los arrecífes, el buceo está cambiando el carácter de los
arrecífes de Bonaire al permitir el incremento de los corales de ramas a expensas de las colonias masivas. El
impacto del estrés de fondo en los corales masivos aparentemente ha sido mayor en presencia del buceo.
Otros estudios han relacionado enfermedades infecciosas al daño del tejido del coral y las tasas de abrasión
altas que estimamos en los sitios de buceo podrían ocasionar que los corales sean más susceptibles a enfer-
medades y por lo tanto mediando la disminución de corales masivos. Nuestro estudio muestra que aún los
niveles bajos de buceo pueden tener efectos pronunciados, manifestados en forma de sesgo en los patrones de
dominancia en lugar de una pérdida general de la cobertura del coral. Los arrecífes de Bonaire tienen las
coberturas más altas de coral y la mayor representación de colonias ancestrales de arrecifes que en cualquier
lugar del Caribe. La conservación de las características de estos arrecífes requierá de controles aún más estric-

tos sobre la intensidad del buceo.

Introduction

Coral reefs are among the most diverse and spectacular
of marine ecosystems. They occur predominantly in the
waters of tropical, developing countries and provide a
vital source of food and income for millions of people
(Munro 1996). Although the gross primary production
by reefs is enormous, net fishable productivity is limited,
and there is now widespread evidence of adverse eco-
system-level consequences of intensive overfishing (Roberts
1995; Polunin & Roberts 1996).
There is an urgent need to find income-generating al-
ternatives to extractive use of coral reef resources (Bir-
keland 1997). Tourism is perceived as the alternative
with potential to provide the greatest revenues (Cesar
1996; Vogt 1996; Hodgson 1997). It brings economic
benefits to local communities and may help protect
reefs by providing an incentive to conserve them. Many
studies have shown, however, that tourism causes signif-
icant damage to reefs (Salvat 1987; Roberts & Harriott
1994; Prior et al. 1995; Rouphael & Inglis 1995; Allison
1996; Harriott et al. 1997; Medio et al. 1997; N. Chad-
wick-Furman, unpublished data). To ensure long-term vi-
ability, it is important that tourist use is kept below dam-
aging levels, but few studies have provided guidance on
sustainable reef capacity (but see Hawkins & Roberts
1992

a

, 1994, 1997; Dixon et al. 1993). We examined
how one of the most popular manifestations of coral
reef tourism, scuba diving, has affected reefs of the Car-
ibbean island of Bonaire. Our findings shed new light on
the question of how to balance conservation and eco-
nomic development of reef resources.
In terms of coral cover, biodiversity, and fish commu-
nities, Bonaire has some of the best coral reefs remain-
ing in the Caribbean (Ginsburg 1994). With tourism a
mainstay of the island’s economy, recreational divers
form a majority of the visitors and contributed approxi-
mately $32 million in revenues in 1991 (Dixon et al.
1993). The people of Bonaire are aware of the value of
their reefs and, recognizing potential threats from tour-
ism and development, established the Bonaire Marine
Park in the early 1980s (Fallon Scura & van’t Hof 1993).
Management of the park is achieved through a combina-
tion of user regulations, such as a prohibition on
spearfishing, and zoning of activities. Damage caused by
boat anchors was identified as a key threat, so mooring
buoys were established at all dive sites when the park
was established (van’t Hof 1983). The park is supported
by user fees levied on recreational divers (Dixon et al.
1994), and wardens patrol daily to ensure compliance
with regulations.
In 1991, when the reef was faced with a rapidly in-
creasing number of divers, the World Bank commis-
sioned a study to examine how diving was affecting the
island’s reefs (Dixon et al. 1993; Fallon Scura & van’t Hof
1993). The study concluded that sites had a carrying ca-
pacity of between 4000 and 6000 dives per year and that
increases in diving intensity above this level could result
in unacceptable damage to reefs. By 1994 diving inten-
sity had increased to the point where some areas were
being dived close to 6000 times per year.
Effects on fish communities are especially interesting
given that, under the supervision of dive guides, divers
are allowed to feed fish in Bonaire. There has been
much controversy over but little study of whether or not
this activity is harmful. In some marine parks it has al-
ready been banned (e.g., Saba Marine Park in Nether-
lands Antilles and Ras Mohammed Marine Park in Egypt).
Feeding fish might alter the natural composition of the
reef community, adversely affecting certain fish popula-
tions while favoring others, notably predatory species
such as snappers and moray eels (Sweatman 1996). Indi-
rectly, it might even affect corals and other invertebrate
communities, but Sweatman’s (1996) study of the ef-
fects of tourist pontoons on Great Barrier Reef fish and
coral communities suggested that this was not the case.
Feeding may also make fish behave aggressively toward
divers, attacking them in anticipation of food. People in
favor of feeding fish argue that it is a popular attraction
that can be used to concentrate diver activity away from
more vulnerable areas of reef. At the time of the study,
fish in Bonaire were regularly fed by dive guides, and or-