New research examines impact of mass tourism on reefs in the Philippines
Reef-based tourism has been developing rapidly in recent decades yet its impacts on reef ecosystems are often overlooked. There is now a considerable body of research on the possible impacts of viewing whales, dolphins etc on the marine mammals themselves, but what are the effects on the ecosystems they live in? New research, published online in Enviornmental Management, examines whether large-scale whale shark tourism in the Philippines affects reef condition.
The research was conducted in Tan-awan, Oslob, Philippines. This small municipality on the south coast of Cebu, has become a domestic and international tourism hotspot since 2011, attracting over 300,000 visitors in 2015 and doubled since then. The mass tourism phenomenon is fueled by the year-round presence of whale sharks along the local shallow reef. This unusual aggregation is maintained by the local tourism association provisioning (feeding) the whale sharks with up to 50 tons of Uyap (sergestid) shrimps annually. While most of the studies to date focus on the whale shark population and tourism perception, this is the first study that investigates the impacts of intensive provisioning and concentrating tourism activities on the health of the largely understudied yet highly vulnerable local reef ecosystem.
The data presented in the paper shows that in comparison to a reference site further south the coast, Tan-awan is affected by greater impacts of degradation as indicated by higher macroalgae and lower coral density as well as a less diverse coral community dominated by weedy corals (Pocillopora) and stress-tolerant (Porites) corals. Furthermore, using the advanced technique of stable isotope analysis on the individual growth ring (biogenic archives) of the species studied, preliminary results reveal anthropogenic nitrogen inputs in Tan-awan. Although an average 1‰ isotope enrichment found in the tourism site relative to the reference site could indicate anthropogenic nitrogen inputs in the tourism site, this enrichment was consistent over time and existed before the tourism developed. Nevertheless, the authors caution against the imminent threat of local eutrophication caused by the continued inputs of nitrogen derived from provisioning and tourism activities.
As the whale shark tourism is projected to grow continuously in the foreseeable future, the research team urges the need for local authorities to implement proper management strategies to mitigate the problems and risks associated with the rapid tourism development.
Dr Alessandro Ponzo, one of the study authors, says: “"Let this be a new beginning. We are positive that with this baseline data at hand the local authorities will look further into the long term and broader ecological impact of mass tourism activities, in Oslob as in many other areas in the country and put a priority into the conservation of their marine resources, shifting towards sustainable tourism and ensuring the local food security through the conservation and restoration of healthy marine ecosystems."
Ziegler et al. (2018) conducted a study on tourist perceptions of the practice of feeding whale sharks in Oslob. Araujo et al. (2014) reported on the population structure and residency patterns of whale sharks at this site, and noted that almost half the animals had propeller scars. Extended residency and differences in lagged identification rates suggest behavioural modification on provisioned individuals.
Journal Reference:
C. W. Martin Wong, Inga Conti-Jerpe, Laurie J. Raymundo, Caroline Dingle, Gonzalo Araujo, Alessandro Ponzo, David M. Baker. Whale Shark Tourism: Impacts on Coral Reefs in the Philippines. Environmental Management, 2018; DOI: 10.1007/s00267-018-1125-3