Impacts of SCUBA divers in the Silfra groundwater fissure : ecological disturbance and management
As is common with increasing tourism the world over, the rapid growth of the Icelandic tourism industry may negatively impact ecosystems in areas that tourists visit. The Silfra groundwater fissure in the Thingvellir National Park has seen a rapid increase in the number of entrees, receiving just below 20.000 divers and snorkelers in 2014. This interdisciplinary thesis explored the relationship between the growing number of dive tourists and potential environmental impacts by: 1) comparing algal biomass and zoobenthic diversity of Silfra to Flosagjá, a fissure where diving is prohibited, 2) comparing algal biomass and zoobenthic diversity between areas of different dive-usage within Silfra, 3) recording diver underwater behavior to assess the mechanisms and ecological consequences behind diver-related ecological disturbances and 4) analyzing perceptions and experiences of dive company operators, dive-guides, dive-tour customers and the Thingvellir National Park officials surrounding the use of Silfra as a dive-site. Results indicated the presence of ecological disturbance in Silfra, especially through algal detachment as algal biomass was less in Silfra than Flosagjá and exhibited a negative correlation with dive-use in Silfra. Zoobenthic diversity appeared mostly unaffected, except for species PEI, which decreased with dive-use, providing evidence for the dominance of disturbance-tolerant species in sites with heavy dive-use within Silfra. By assessing diver underwater behavior it was estimated that each diver entering Silfra caused an average of 81 disturbance events, resulting in the removal of algae and the raising of sediment. These consequences mostly occurred as a result of diver fin-generated currents, but contacts by divers were also frequent. Ecological disturbance is likely to escalate with increasing numbers of divers. Analysis of stakeholder perceptions indicated that a further increase in Silfra visitor numbers may damage the tourism experience. This thesis recommends improved management in the currently open fissures for diving in Thingvellir National Park, in addition to a limitation on the number of visitors allowed into Silfra on an annual basis. These management protocols would simultaneously reduce future ecological disturbance and enhance the quality of the tourism experience. For this to be fully achieved, future research need to focus on the establishment of ecological, social and economic carrying capacities for fissure diving and snorkeling in Thingvellir National Park.
Fiskifræði, Líffræði, Meistaraprófsritgerðir, Grunnvatn, Vistkerfi, Kafarar, Þingvellir
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