Effects of Self-Guided Snorkeling Trails on Corals in a Tropical Marine Park

Abstract

Underwater trails are intended as interpretative tools in marine parks, but concentrating divers and snorkelers in defined areas may negatively affect the surrounding environment. We examined spatial and temporal patterns in the effects of use of underwater trails on coral reef flats in the Great Barrier Reef Marine Park, Australia. Changes in benthic assemblages were assessed on two new trails used by snorkelers, two unused (control) trails, and two undisturbed areas. Total percent coral cover, numbers of broken colonies, and living coral fragments were counted 6 months before and 6 months after the new trails began to be used. Spatial patterns of effects around concentrated nodes of use were determined by stratified sampling around and away from the interpretative signs within each trail. Despite comparatively low levels of use (approximately 15 snorkelers per trail per week), snorkelers caused significant damage to corals along the trails. Branching corals (non-Acropora branching corals and Millepora spp.) were most affected. More damage occurred near the interpretative signs than elsewhere on the trails. The numbers of broken branches and damaged coral colonies in the snorkeling trails increased rapidly but stabilized within 2 months of the commencement of use. There was no significant change in overall benthic assemblages within the trails after 6 months of use by snorkelers. Although concentrating snorkelers within confined trails caused increased damage to corals, the effects can be mitigated by appropriate design and placement of the trails and by managing the behavior of snorkelers. Interpretative information should warn users about the damage they may cause when swimming along the trails. Managing the behavior of snorkelers in the water is likely to be more effective in reducing damage than simply applying fixed limits to the amount of use the trails receive. Efectos de Senderos para el Buceo Libre con Esnorquel en los Corales Dentro de un Parque MarinoResumen: Los senderos submarinos tienen la intención de servir como herramientas interpretativas en los parques marinos, pero la concentración de buzos y buceadores libres en áreas definidas puede tener un efecto negativo en el ambiente de los alrededores. Examinamos los patrones temporales y espaciales de los efectos del uso de senderos submarinos en relieves de arrecifes de coral en el arrecife del Parque Marino de la Gran Barrera de Arrecifes en Australia. Los cambios en los ensamblajes bénticos fueron evaluados en dos senderos nuevos usados por buceadores libres, dos senderos sin usar (controles) y dos áreas sin perturbar. Evaluamos el porcentaje de cobertura de coral, el número de colonias rotas, y fragmentos de coral vivo 6 meses antes y seis meses después de que se iniciara el uso de los senderos nuevos. Los patrones espaciales de los efectos alrededor de nódulos concentrados de uso fueron determinados por un muestreo estratificado alrededor y en sitios lejanos de las señales interpretativas de cada sendero. A pesar de los niveles significativament...

Spatial dynamics and substrate impacts of recreational snorkelers and SCUBA divers in Hawaiian Marine Protected Areas

“…Recreation ecology has historically focused on visitor impacts in terrestrial parks and wilderness areas but has more recently evaluated recreation impacts on coral reefs (Leung and Marion 2000;Plathong et al 2000; Barker and Roberts 2004). To date, studies of recreation impacts on coral reefs have been limited to three main types: (1) Benthic surveys where coral damage was compared between high and low traffic areas (e.g., Hawkins and Roberts 1992;Jameson et al 1999;Zakai and ChadwickFurman 2002); (2) Direct impact ('real time') studies where people engaging in specific activities were individually followed to determine the frequency and extent of damage to corals (e.g., Harriot et al 1997;Walters and Samways 2001;Barker and Roberts 2004); and (3) Experimental manipulations where the resilience of different coral species to physical contact was evaluated using simulated trampling, mechanical strength testing and tissue regeneration and fragment survival experiments (e.g., Liddle and Kay 1987;Riegl and Riegl 1996;Rodgers et al 2003).…”

“…The most common recreational activities occurring in Hawaiian MPAs (snorkeling and SCUBA diving) are known to damage coral in other geographic regions (e.g., Plathong et al 2000;Rouphael and Inglis 2001). Trained observers used waterproofed Global Positioning System (GPS) units to track individual divers and obtain high resolution spatial information on recreation impacts within four Hawaiian MPAs.…”

Using Coral Disease Prevalence to Assess the Effects of Concentrating Tourism Activities on Offshore Reefs in a Tropical Marine Park

“…Much of what is currently known about the effects of tourism activities on coral reefs comes from studies of changes in percent coral cover in response to direct physical contact, for example, coral breakage due to activity of divers (Hawkins & Roberts 1992) and swimmers along snorkeling trails (Plathong et al 2000), construction of permanent platforms and moorings (Smith et al 2005), and movement of anchor chains (Schafer & Inglis 2000). The results of previous studies show that the effects of tourism platforms on coral cover are few and isolated (Smith et al 2005).…”

Developing a scuba trail vulnerability index (STVI): a case study from a Mediterranean MPA

“…Nevertheless, an elevate number of divers could induce a degradation of the marine environment (Ward 1990;Garrabou et al 1998) and cause the depletion of the resources that initially constituted the attractiveness for tourist flows (Garrabou et al 1998), reducing, in this way, both natural and aesthetic values of MPAs (Davis and Tisdell 1995;Plathong et al 2000).…”