Canyoning simplifies benthic macroinvertebrate communities in Mediterranean canyons: evidence from Sierra y Cañones de Guara Natural Park

Rocío López-Flores , Diego Mota-Echeandía, Mario Gaspar, David Guzmán Otano

1. Recreational activities in freshwater ecosystems are increasing worldwide, yet their ecological consequences remain poorly understood. Canyoning is one of the most popular nature-based sports in Mediterranean rivers, but quantitative assessments of its effects on aquatic communities are scarce, particularly in protected areas where conservation and recreation coexist. Here, we evaluated how canyoning affects benthic macroinvertebrate communities and whether recreational intensity and hydrogeomorphological characteristics influence ecosystem vulnerability.
2. We evaluated the impact of canyoning on benthic macroinvertebrate communities in six canyons of the Sierra y Cañones de Guara Natural Park (NE Spain). At each canyon, control and disturbed sites were sampled using Surber samplers, and community descriptors, ecological quality indices and taxonomic composition were compared. We also assessed whether the magnitude of the impact was related to visitor pressure and hydrogeomorphological characteristics.
3. A total of 53 taxa were identified across all samples. When sites were pooled, 47 taxa were recorded in control sites and 29 in disturbed sites. Canyoning reduced macroinvertebrate abundance by 69% on average, and 24 families recorded at control sites were absent from disturbed sites. Community composition differed significantly between control and disturbed sites and was characterised by marked declines in sensitive groups, particularly Trichoptera, Coleoptera and Odonata. Visitor pressure influenced the percentage impact on abundance, with high-use canyons showing reductions exceeding 85%. In contrast, richness, diversity and ecological quality indices showed no clear relationship with visitor pressure. Some impact metrics were also associated with hydrogeomorphological characteristics, particularly bankfull width.
4. Our results demonstrate that canyoning can substantially simplify benthic macroinvertebrate communities and reduce ecological quality in Mediterranean canyons. The severity of these effects is influenced not only by visitor pressure but also by local hydrogeomorphological conditions.
5. This study provides new evidence that recreational disturbance can substantially alter benthic macroinvertebrate communities in Mediterranean canyon ecosystems. It also suggests that local environmental characteristics may contribute to differences in ecosystem vulnerability, highlighting the importance of considering ecological context when assessing the sustainability of recreational activities in freshwater ecosystems.