Conservation of freshwater fish biodiversity: a challenge for the countries of...(the relative influence of the particular...)

Date:3/26/2008

the relative influence of the particular characteristics of each ecosystem and human activities on the diversity of the non-native fish species. Three hypotheses were tested: the biotic resistance, biotic acceptance and human activity. The first suggests that a high diversity of freshwater fish in the host ecosystem acts as a barrier to the establishment of non-native fish specie populations. The second postulates conversely that, for a given ecosystem, non-native species diversity follows that of native species because favourable ecological conditions for the latter are also suitable for the newly arrived species. As for the third, it takes account of the different indicators at river-basin scale (gross domestic product, percentage of land urbanized, population density), that can yield determination of the relation between anthropic pressure and non-native species diversity.

The three hypotheses relative weight was measured using statistical methods. For the whole set of river basins investigated, the environmental conditions of fluvial ecosystems were found to have practically no influence on the exotic species diversity. On the contrary, it is the human factors, and especially the intensity of economic activities measured by the GDP, which determine the number of non-native species present in a river basin. These results thus suggest that the economic development foreseen in the developing countries should be accompanied by a rise in the number of non-native freshwater fish species. Given that biological invasions are considered as one of the main causes of biodiversity loss, such a scenario would probably be detrimental to the aquatic biodiversity conservation of these regions. This study indicates that exceptional river ecosystems, like the Amazon Basin in South America or that of the Congo in central Africa, are still hardly affected by species introduction. For example, no more than 1% of the 3000 species of fish recorded in the River Amazon are non-nat
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Contact: Gregory Flechet fichesactu@paris.ird.fr 33-014-803-7607 Institut de Recherche Pour le Dveloppement Source:Eurekalert

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