Journal Article

Climate Change Forces New Ecological States in Tropical Andean Lakes

Wolfe, Alexander P., Michelutti, Neal, Vuille, Mathias, Hobbs, William O., Smol, John P., Cooke, Colin A.

2015

Overview

Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Air temperature / Alpine climates / Alpine environments / Atmospheric pressure / Bacillariophyta / Biodiversity / Chlorophyll / Climate Change / Climate effects / Cores / Diatoms / Ecological effects / Ecosystem biology / Ecosystems / Fossils / Freshwater resources / Glaciers / Hydrogen-Ion Concentration / Ice cover / Laboratories / Lake sediments / Lakes / Lakes - chemistry / Local population / Mountain lakes / National parks / Nutrients / Paleoecology / Phytoplankton / Plankton / Polar environments / Pressure distribution / Production increases / Sediments / Sediments (Geology) / Shrinkage / South America / Surface water / Temperature rise / Thermal stability / Tropical Climate / Water circulation / Water column / Water resources / Water shortages / Water stratification / Wind speed