Fish assemblages from touristic and non-visited headwater streams differ

Nature-based tourism is a growing industry in recent years, including underwater trails in clear headwater streams. These activities, however, bring little known impacts, most of them in the individual and population levels. To investigate if human presence can affect the fish community, we compared similar reference and tourism areas in terms of species accumulation curve, ecological indicators (richness, total abundance, diversity and dominance), composition similarity and indicator species. Only fish abundance did not differ between reference and tourism areas. Richness, diversity and dominance were all higher in tourism areas. Fish species composition also differed between reference and tourism, guided by species substitution. We add ecological data to previous behavioral studies that have already evidenced the effects of tourism on fish. We also suggest a strict control of the number and permanence of visitors in the water, the forbiddance of fish feeding and maintenance of the riparian coverage to avoid irreversible damages to these fragile environments.