Managing Tourism and Environment—Trail Erosion, Thresholds of Potential Concern and Limits of Acceptable Change

Natural area tourism may contribute to deterioration in biophysical environments important for sustainable conservation of biodiversity and/or historically significant sites. Levels of protection within the IUCN guidelines provide general descriptors of desirable outcomes, and the Limits of Acceptable Change (LAC) management tool has often been implicitly applied. This article presents an initial attempt to assess the value of Thresholds of Potential Concern (TPC) relative to LAC as management frameworks for protected areas, using the example of trail width as an indicator of visitor impacts on vegetation, soil, water and, potentially, visitor safety. Visitor preferences relating to trail width were incorporated when applying the TPC and LAC principles. Sections of three walking trails in a high-visitation national park near Sydney, Australia, were measured at ~10.7 m intervals: the mean trail widths were 1.6 m, 1.8 m and 2.14 m. Of the 115 recreationists surveyed, 16% of those having the greatest tolerance towards management interventions (‘Non-purist’ wilderness category) viewed a trail ≥ 2 m wide as acceptable, but 96% of ‘Purists’ nominated a maximum of ≤1.5 m. The TPC was found to provide a broad strategy for identification, assessment and grading of multiple biophysical thresholds within an ecological framework. Combined with stakeholder information, the TPC allows for timely, proactive and calibrated management responses to maintaining biophysical and social sustainability.

Precision and cost-effectiveness of bioindicators to estimate nutrient regimes on coral reefs

Bioindicators are useful for determining nutrient regimes in marine environments, but their ability to evaluate corals reefs in different ecological states is poorly understood. The precision, availability and congruency of eight potential bioindicators (brown macroalgae, green macroalgae, turf algae, cyanobacteria, soft corals, zoanthids, sponges, and sediment) and their stable isotopic and elemental signatures (δ¹⁵N, δ¹³C, %N, %C, and C:N Ratio) were assessed across 21 reefs in the Inner Seychelles. The coefficient of variation (CoV) for δ¹⁵N showed that green and brown macroalgae were highly precise (2.47 ± 0.95, n = 11; 4.68 ± 1.33, n = 16, respectively), though were less common on coral-mortality reefs relative to macroalgal-dominated ones. Zoanthids were also highly precise for δ¹⁵N (2.98 ± 1.20), but were more readily available regardless of reef state (n = 18). Congruency was low among these indicators, suggesting that different physiological mechanisms for nutrient processing have a stronger influence on a bioindicator's effectiveness than reef state.