Aim The aim of this work is to update the distribution data of Galaxiidae in South America, relating extant distribution to physiological and reproductive characteristics of the species, latitude, temperature, and post‐glacial opportunities for colonization.
Location Lakes and rivers of Patagonia.
Methods We compared, and eventually reconsidered, general data about distribution based on the original literature about capture sites, incorporating several published and unpublished data to the analysis of the biological traits and distribution of Galaxiidae.
Results The more consistent issue in the comprehension of galaxiid biogeography in South America is the ability to establish landlocked populations. Different founding events in landlocked populations of Galaxias maculatus suggest the possible existence of older and younger landlocked populations. This difference in the time since the establishment of lacustrine populations could have been expressed in their ability for colonization of post‐glacial areas. Galaxias maculatus, Aplochiton and Brachygalaxias are more clearly excluded from the post‐glacial area than G. platei. For all the species we could note a more abundant record of lake populations at the area of glacial refuges. It could be noted that the most successful species, Galaxias platei, is a specialized deep bottom dweller. Deep bottom dwelling helps to endure winter constraints and it appears to be an alternative to the colonization of the littoral and limnetic zones of post‐glacial lakes, the prefered habitat of the other Patagonian fish species.
Main conclusions At the end of this process of post‐glacial colonization, in the beginning of twentieth century, man introduced several salmonid species in Patagonia. In addition, antropogenic actions had its more recent consequences in global warming. Nowadays we were able to observe new localities for Brazilian fishes into the Austral Subregion and expect some changes in the distribution of Galaxiidae. Northern limits for all species and southern limits for landlocked G. maculatus, Brachigalaxias bullocki and Aplochiton zebra, could be displaced southward. Probably, the species less affected by the changes will be G. platei. These predictions could be accurately formulated using the model of B.J. Shuter & J.R. Post (1990) Transactions of the American Fisheries Society119, 314–336, when biological database on these species are completed.
The Endangered frog Atelognathus patagonicus is endemic to the Laguna Blanca wetland system, Patagonia, Argentina. This species has undergone a significant contraction of its original distribution, including loss of the main population from the largest lagoon, Blanca. The decline of A. patagonicus was first perceived in 1986 and was thought to be at least partially associated with the anthropogenic introduction of the perch Percichthys colhuapiensis for sport. To evaluate the potential impact of P. colhuapiensis on A. patagonicus we surveyed for both species in 28 lagoons, and found A. patagonicus present in 23. These lagoons represent, however, only a small percentage of the total wetland area. The presence of A. patagonicus was associated with lagoons characterized by absence of P. colhuapiensis and high abundance of macrophytes. The most severe problem facing the remaining populations is in the many lagoons currently not protected by Laguna Blanca National Park. Conservation efforts need to focus on the prevention of fish introductions in the wetlands areas on private land. A project to restore A. patagonicus to Laguna Blanca, and educational programmes emphasizing the protection of Patagonian wetlands as reservoirs of regional biodiversity, are currently under development.
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