Canyoning practice highly reduces macroinvertebrate abundance and simplifies the community structure. Data file. ECOSPHERE

Outdoor sport has grown significantly over the last few decades. While it fosters socioeconomic development in remote areas and communities, it can also contribute to environmental degradation in well-preserved regions. Canyoning, which entails descending natural canyons through trekking, swimming, and abseiling, is an activity that remains under-researched. In Europe, one of the main destinations for canyoning is the Sierra y Cañones de Guara Natural Park (Aragón, Spain). This paper aims to assess the impact of canyoning on the benthic macroinvertebrate fauna by examining six different canyons, marking the first attempt in Europe to evaluate the ecological impact of this activity on stream ecosystems and to suggest management guidelines. The abiotic characteristics of the streams studied were documented and macroinvertebrate community samples were collected from both frequented and undisturbed stretches during the same day (n=12). The resulting data were used to calculate several taxonomical, functional, and ecological status indices, followed by a multivariate analysis to assess the effect of trampling on benthic communities. The results unequivocally demonstrated the negative impact of canyoning on several metrics, including an 80% decline in invertebrate abundance and approximately a 50% reduction in taxa richness and ecological status. These changes resulted in a general simplification of the metacommunity structure. The hydromorphological characteristics of the canyons were key factors in understanding the vulnerability of these ecosystems and their potential for recovery. Given the high number of annual visitors, the progression of climate change, and the threat of invasive alien species (IAS), unmanaged recreational use of canyons poses a direct risk to river biodiversity in protected areas. Our results suggest that, without proper regulation, these factors could lead to significant deterioration of river ecosystems, endangering species preservation and the integrity of natural habitats within these conservation zones.