Fragile Ecosystems, Mathematically Speaking


In all fields of science, researchers rely on mathematical models to make predictions about future events (will an asteroid hit earth?), predict how a system might react if perturbed, (does an excess of carbon dioxide in the atmosphere lead to global warming?), and even to investigate why a process works the way it does (how do neurons in our brain communicate with each other?).

In a recent issue of the journal Nature, University of Wisconsin researchers report that they have developed a mathematical model to examine the behavior of a complex lake ecosystem involving fish, insects, and hard-shelled algae known as diatoms. The model was developed using data from an Iceland lake whose fish population declined rapidly in over the last 25 years.  The model suggests that the lake's insect population is extremely sensitive to changes in the ecosystem, and that the observed crash in fish population may have been caused by human activity.

The explanation goes like this: lake dredging led to subtle changes in the diatoms' ecosystem that in turn resulted in profound changes in the lake's food chain. Dredging changed the algae's distribution in the lake, which led to fewer algae for insects to eat, which lead to fewer insects for the fish to eat.  In a normal ecosystem, the population of insects normally rises and falls over a regular, predictable interval.  But in this instance, the interval is irregular. This may explain why the fish population collapsed.

Most importantly, this research reinforces the sensitivity of natural ecosystems to seemingly small natural and/or man-made changes.

Original Article


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