Trouble in the tropics

In our story on “Turning up the heat on freshwater interactions” we discussed the importance of freshwater ecosystems, their parlous state, their vulnerability to climate change and the value of riparian restoration. In a recent review of the impacts of agricultural expansion in the tropics (Laurance et al., 2014), the plight of freshwater ecosystems was underscored.

Here’s how William Laurance and colleagues described it: “In the tropics, large increases in water harvesting, damming, and diversion of rivers will be needed for agricultural expansion, intensification, and associated electricity needs. Over 150 large (>2 MW) hydroelectric dams are being planned just for the Andean-Amazon region. Flood plains will be prime targets for expansion of irrigated farming, especially in Africa. Many watercourses and lakes will suffer altered flows, higher temperatures, lower dissolved oxygen levels, and elevated loads of sediments, nutrients, pesticides, and other pollutants. Declines of larger fishes, river migrants, and species requiring unpolluted, highly oxygenated waters and specialized microhabitats are common. Many locally endemic fish and invertebrates are found entirely outside of protected areas, and relatively few protected areas encompassentire watersheds. As a result, freshwater habitats are among the planet’s most imperiled ecosystems.”

Laurance WF, J Sayer & KG Cassman (2014). Agricultural expansion and its impacts on tropical nature. Trends in ecology andevolution 29: 107-116.


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