Study: Critical Nutrients in Ecosystems Change when Fish Become Extinct

Study: Critical Nutrients in Ecosystems Change when Fish Become Extinct

Source: underwatertimes

3/27/2007

Ecosystems are such intricate webs of connections that few studies have been able to explore exactly what happens when a species dies out.

Now, a Cornell study using computer simulations has teased out how the disappearance of a freshwater fish can affect the availability of certain nutrients that other species rely on.

Algae, at the base of the food chain, for example, rely on fish to cycle back into the water such nutrients as nitrogen and phosphorus, which are otherwise locked up in animal or plant cells. Fish excrete dissolved nutrients back into the water, making them available to algae, which need them to grow.

The study, published in the Feb. 27 issue of the Proceedings of the National Academy of Sciences, finds that overfishing could threaten the overall health of an ecosystem because it targets important fish species that play major roles in recycling nutrients. In fact, 20 percent of fish species accounted for more than half of all the recycled nutrients in the ecosystems studied, the computer simulations found.