Abstract

Chilean Patagonia encompasses the two southernmost terrestrial ecoregions of the temperate forest biome of South America (North-Patagonian and Sub-Antarctic Magellanic) and the two western marine ecoregions of the Magallanes Province (Chiloense, and Channels and Fjords of Southern Chile). These ecoregions are immersed in a complex mosaic of terrestrial (with marked altitudinal gradients), freshwater (including wetlands, rivers, lakes, and lagoons) and marine ecosystems (with myriad islands, channels, and fjords). With more than 100,000 km of coastline, most environments in the region exhibit strong land-sea interdependency in energy and nutrient flows. The goals of the chapter are to: (i) describe the main ecological features of the marine-terrestrial interface in the channels, fjords, and archipelagoes; (ii) identify major anthropogenic impacts on marine-terrestrial connectivity; (iii) describe the most important matter and energy flows across aquatic and terrestrial ecosystem; (iv) discuss the conservation status of species that are dependent on this interface; (v) identify those public protected areas that have extensive areas of marine-terrestrial interface. The major nutrient exchanges in the marine-terrestrial interface include carbon and nitrogen-rich sediment flows transported to the ocean by the rivers and streams, and abundant debris of siliceous rocks from land to ocean carried by rivers draining glaciers and ice fields. The most important vectors of biological transport of materials between the ocean and land are large marine mammals and seabirds. This includes historical records of whale landings that mobilize nutrients from ocean bottoms to the coastal zones and large populations of seabirds that nest in the archipelagos. Major threats to the marine-terrestrial interface include the massive populations of naturalized salmon that circulate in the fjords, streams, and channels. Salmon proliferation has altered the nutrient transport from the ocean to the continental rivers. Three species of exotic mammals have increased in numbers and impact at the interface between oceans, land, and freshwater systems—the beaver (Castor canadensis), the North American mink (Neovison vison), and the muskrat (Ondatra zibethicus). In contrast to traditional views on conservation and management that segregated land–ocean interfaces, our analysis in this chapter suggests that in order to understand ecosystem functioning in Chilean Patagonia as well as to establish comprehensive conservation programs, it will be essential to address the interrelationships of biophysical processes at the marine-terrestrial interface.