Watershed conservation and aquatic benthic macroinvertebrate diversity in the Alberto D’Agostini National Park, Tierra del Fuego, Chile

MICHELLE C. MOORMAN; CHRISTOPHER B. ANDERSON; ÁLVARO G. GUTIÉRREZ; RINA CHARLIN; RICARDO ROZZI

ANALES DEL INSTITUTO DE LA PATAGONIA

UNIVERSIDAD DE MAGALLANES

Año: 2006 vol. 34 p. 41 - 58

0718-6932

Southern South America is known globally for its remote and rugged landscapes, which include one of Chile’s largest national park: Alberto De Agostini. The singular nature of this area, however, is also found in is flora and fauna. The recent designation of Magellanic Sub-Antarctic Forests as one of the world’s last wilderness areas propelled us to question whether there was detailed evidence for this classification in the Tierra del Fuego portion of the De Agostini Park. Therefore, in January 2004 and 2005 boat-based expeditions were carried out around the south-west portion of Tierra del Fuego Island, as well as adjacent islands south of the Beagle Channel. Their purpose was to evaluate the current state of the park’s natural resources and to create a baseline of physical, chemical, biological and ecological information that can be used in the administration, conservation and future research of this area. We utilized a watershed analysis approach, examining vegetation cover, habitat type and disturbance. Along the major watercourse of each basin, we quantified the presence of exotic species, water quality and the aquatic macroinvertebrate assemblage. We found that habitats types were highly diverse with mixed and deciduous forests dominating the eastern portion of the study area and Magellanic evergreen forests and tundra in the west. On average, approximately 50% of the watersheds’ areas were covered by forests with exposed rock and tundra occupying 28% and 17%, respectively. Glaciers and herbaceous habitats only made up 3% of study sites. Disturbances from human impacts and introduced species were rare and focused mainly outside the national park and in the eastern portion of the Brecknock peninsula, but significant localized exceptions occurred even in isolated fjords and where fishing and tourism activities were being carried out. Finally, one quality of the archipelago that had not previously been well evaluated was its freshwater ecosystems and biota. Our water quality analysis showed that these streams were highly pristine and contained a diverse and largely endemic aquatic macroinvertebrate fauna (e.g. Trichoptera Monocosmoecus hyadesi and Rheochorema magellanicum and the Plecoptera Notoperla fuegiana). Furthermore, many of these taxa provide ideal taxonomic, evolutionary and biogeographic study subjects, given their isolated and ancient lineages, as well as the fact that several orders and families reach their global southern distribution limit in the Fuegian Archipelago (e.g. Ephemeroptera, Trichoptera, Plecoptera and Diptera Simuliidae and Coleoptera Dytiscidae). We expect these data to further a greater appreciation and understanding of the pristine areas of Tierra del Fuego and that it will help to establish ecological monitoring criteria for Alberto De Agostini National Park, which is also part of the new Cape Horn Biosphere Reserve, and mitigate impacts of development on an area that is currently still in a largely natural state.