Climate induced shifts in South American Lake Ecosystems - Threats and Novel Restoration Perspectives

Shallow lakes are an important natural resource in many densely populated areas in South America. Temperate shallow lakes are among the best understood ecosystems in terms of stability and community dynamics. In particular, it has been shown that such lakes tend to be in either of two alternative stable states: a clear state dominated by submerged plants and high in biodiversity, and a turbid state dominated by phytoplankton which is much lower in biodiversity and has various water-quality problems that greatly reduce human utility.

Preliminary work suggests that shallow lakes may be very sensitive to climatic change. However, our ability to predict effects of expected climate change is limited severely by a lack of appropriate data on lower latitude lakes. In the proposed project we will sample 100 lakes along a latitudinal gradient from Brazil to Argentina and analyze sediment cores and time series of satellite images to address the hypotheses that I) average climatic conditions affect the critical nutrient level at which shallow lakes fall into a turbid state, and II) extreme meteorological conditions can induce shifts between alternative stable states.

The anticipated results will be of great fundamental value as they would provide the first test of the hypothesized response of multiple stable ecosystems to climate change. Furthermore, they will provide water quality managers in South America as well as Europe with a tool for predicting potential effects of climate change. A practical implication is that predicted El Niņo or La Niņa events may be used as a 'window of opportunity' to shift lakes to a clear state with relatively little effort.

For more details on the project click here.

Last updated: by Egbert van Nes. Please mail comments and questions to: