New article: Determinants of homogenization and differentiation of native freshwater fish in a Mediterranean Basin

A new article led by Virgilio Hermoso at Griffith University (Brisbane, Australia), and in which Miguel Clavero has participated, provides new insights on the role that introduced species play in the homogenization process of freshwater fish communities and their relation with reservoirs.

They evaluate the extent and determinants of fine-scale alteration in native freshwater fish assemblages among stream reaches throughout a large river basin (Guadiana) and consider the implications of these changes for the long-term conservation of native fishes.

The study quantified the magnitude of change in compositional similarity between observed and reference assemblages and its potential effect on natural patterns of compositional distinctiveness. Reference assemblages were defined as the native species expected to occur naturally (in absence of anthropogenic alterations) and were reconstructed using a multivariate adaptive regression splines predictive model.

They found a significant trend towards homogenization for native fish assemblages. Changes in native fish distributions led to the loss of distinctiveness patterns along natural environmental gradients. Introduced species were the most important factor explaining the homogenization process. Homogenization of native assemblages was stronger in areas close to reservoirs and in lowland reaches where introduced species were more abundant.

Increasing threats to freshwater biodiversity are rapidly changing the distinctiveness of regional species pools and local assemblages. Biotic homogenization/ differentiation processes are threatening the integrity and persistence of native biodiversity patterns at a range of spatial scales and pose a challenge for effective conservation planning. The implementation of efficient conservation for the maintenance of native fish diversity is seriously threatened by the homogenization processes. The identification of priority areas for conservation is hindered by the fact that the most diverse communities are vanishing, which would require the selection of broader areas to adequately protect all the species. Given the principal role that introduced species play in the homogenization process and their relation with reservoirs, special attention must be paid to mitigating or preventing these threats.

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Nou article: Determinants de l’homogenització i diferenciació dels peixos nadius a la Mediterrània

En un nou article liderat per Virgilio Hermoso de la Griffith University a Brisbane, Australia, i en el que ha participat en Miguel Clavero, es presenten noves investigacions sobre el paper de les espècies introduïdes en el procés d’homogenització de les comunitats de peixos d’aigua dolça de sistemes Mediterrànis.

Hermoso, V., Clavero, M. & Kennard, M.J. (2012) Determinants of fine-scale homogenization and differentiation of native freshwater fish faunas in a Mediterranean Basin: implications for conservation. Diversity and Distributions.