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Assessment of Native Stream Biodiversity and the Influence of Invasive Species in Tierra Del Fuego, Chile

Michelle C. Moorman1,2,3*, Christopher B. Anderson2,4, Paul Szejner2,5, and Rina Charlin2

1U.S. Geological Survey, 3916 Sunset Ridge Rd, Raleigh, NC 27560 USA
2Omora Ethnobotanical Park, Puerto Williams, Region XII, Chile
4Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 USA
4Institute of Ecology, University of Georgia, Athens, GA 30602 USA
5Department of Forestry, University Austral de Chile, Valdivia, Region X, Chile

Abstract

The Cape Horn Biosphere Reserve (CHBR) was recently designated as one of the world’s last remaining pristine wilderness areas. However, at the same time invasive species can be found along its fringes. Since 2004 we have been assessing aquatic biodiversity and the effects of introduced species to provide physical, chemical, biological, and ecological information to guide management, conservation, and future research activities in the area. Streams in this area contained relatively diverse (mean taxa richness = 12 in natural sites) and largely endemic aquatic macroinvertebrate fauna (e.g., Trichoptera Monocosmoecus hyadesi and Rheochorema magellanicum and Plecoptera Notoperla fuegiana), but freshwater fish species were rather species-poor and lacked endemics (Galaxias maculatus, Aplochiton zebra, and A. tenatius). The introduced North American beaver (Castor canadensis) were found in nearly all the watersheds of the study area, except for the extreme western and southwestern portion of the archipelago. Their impoundments reduced the richness and diversity of benthos, but increases invertebrate biomass and the abundance of G. maculatus. Two trout species (Salvelinus fontinalis and Oncorhynchus mykiss) were also found throughout Navarino and Hoste Islands in areas previously settled by humans, indicating that the presence of trout is related to human inhabitation. An increase in the abundance and biomass of trout is negatively related to the abundance and biomass of native fish species, but less so then in other areas of Tierra del Fuego where brown trout (Salmo trutta) are present and have severely impacted the native fish communities. Prevention of the introduction of highly invasive brown trout is necessary in order to preserve the native fish communities. In conclusion, our findings illustrate that the invasion of exotic species on the fringes of the Cape Horn Biosphere Reserve is fundamentally altering the pristine nature of its aquatic ecosystems, and their control should be a high priority.

Mooreman, M., Anderson, C.B., Szejner, P., and Charlin, R., 2006, Assessment of Native Stream Biodiversity and the Influence of Invasive Species in Tierra Del Fuego, Chile: Proceedings of the National Water-Quality Monitoring Council National Monitoring Conference, May 8-12, 2006, San Jose CA.