Article

Fish Invasions in the World's River Systems: When Natural Processes Are Blurred by Human Activities

Laboratoire Evolution and Diversité Biologique, UMR 5174, CNRS-Université Paul Sabatier, Toulouse, France.
PLoS Biology (Impact Factor: 11.77). 03/2008; 6(2):e28. DOI: 10.1371/journal.pbio.0060028
Source: PubMed

ABSTRACT Because species invasions are a principal driver of the human-induced biodiversity crisis, the identification of the major determinants of global invasions is a prerequisite for adopting sound conservation policies. Three major hypotheses, which are not necessarily mutually exclusive, have been proposed to explain the establishment of non-native species: the "human activity" hypothesis, which argues that human activities facilitate the establishment of non-native species by disturbing natural landscapes and by increasing propagule pressure; the "biotic resistance" hypothesis, predicting that species-rich communities will readily impede the establishment of non-native species; and the "biotic acceptance" hypothesis, predicting that environmentally suitable habitats for native species are also suitable for non-native species. We tested these hypotheses and report here a global map of fish invasions (i.e., the number of non-native fish species established per river basin) using an original worldwide dataset of freshwater fish occurrences, environmental variables, and human activity indicators for 1,055 river basins covering more than 80% of Earth's surface. First, we identified six major invasion hotspots where non-native species represent more than a quarter of the total number of species. According to the World Conservation Union, these areas are also characterised by the highest proportion of threatened fish species. Second, we show that the human activity indicators account for most of the global variation in non-native species richness, which is highly consistent with the "human activity" hypothesis. In contrast, our results do not provide support for either the "biotic acceptance" or the "biotic resistance" hypothesis. We show that the biogeography of fish invasions matches the geography of human impact at the global scale, which means that natural processes are blurred by human activities in driving fish invasions in the world's river systems. In view of our findings, we fear massive invasions in developing countries with a growing economy as already experienced in developed countries. Anticipating such potential biodiversity threats should therefore be a priority.

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Article: Fish Invasions in the World's River Systems: When Natural Processes Are Blurred by Human Activities

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    • "La introducción de peces en aguas continentales es de larga data y se ha realizado principalmente con fines de acuicultura, acuariofilia y pesca recreativa (Welcomme 1988). Sudamérica es uno de los seis " hotspots " globales de invasión de peces de agua dulce (Leprieur et al. 2008) y muestra una significativa homogenización de su fauna de peces (Villéger et al. 2011). Los ríos y lagos de Chile no han sido la excepción, estando la gran mayoría de estos sistemas continentales invadidos por una o más especies de peces exóticos. "
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    • "The study and management of non-native fish species in emergent economies like Mexico should be a priority due to the positive relationship between the number of nonnative species and economic development (Leprieur et al., 2008). There is an urgent need for studies focused on areas that experience high homogenization of fish fauna such as Central Mexico (Villéger et al., 2011). "
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