Alterações da paisagem são indicadoras da ocorrência de peixes não nativos na bacia do Rio Doce?

Abstract

The introduction of species, when followed by their establishment in a new location (i.e., biological invasion), is one of the greatest threats to global biodiversity. Studies have shown that this process can be facilitated by the interaction with other human pressures. Commonly, introduced species have life history attributes that allow them to persist in places that native species cannot tolerate. In this context, landscape changes induced by land-use activities (e.g., agriculture, grazing, urbanization, mining) can act as drivers for the establishment of non-native species. Particularly for freshwater ecosystems, dams can also act as facilitators of invasions by changing habitat and increasing propagule pressure, as well as the presence of roads, providing human access, the main agent of introductions. We examined the relationship between land use and land cover (LULC), dams and roads and the occurrence of non-native fishes in the Doce River basin. We hypothesized that the higher the level of degradation, the higher the frequency of occurrence and richness of non-native species. We considered 41 sub-basins from Doce River basin as sampling units. The occurrences of non-native species were obtained through databases and compilation of specialized literature. We identified 1040 records of 35 non-native fish species, belonging to 17 families and six orders. The species with the highest occurrences were the lebiste Poecilia reticulata, the tamboatá Hoplosternum littorale, and the piabinha Knodus moenkhausii. We found a positive relation between % agriculture and cattle ranching and the total richness of non-native fish. This landscape alteration was also positively associated to the presence of non-native fishes whose the main introduction vectors were sport-fishing, aquaculture and baitcasting, indicating that more degraded sub-basins were the most invaded. This study is considered an important step towards the understanding of the distribution patterns of non-native fish species and its relation with environmental degradation in the Rio Doce basin. The information generated can help in the planning of management actions and public policies for the region.