Loss of Predators Impacts Food Chain
Sharp decline upsets balance of the world’s ecosystems
July 19, 2011
Sea otters maintain kelp forests in the ocean by preying on kelp-grazing sea urchins.
Jim Estes studies sea otters. The University of California, Santa Cruz professor of ecology and evolutionary biology says these furry marine mammals - once hunted to near extinction - are important to the health of coastal North Pacific ecosystems.
“We have discovered that sea otters have an important limiting effect on sea urchins and that allows the kelp forest to persist," he says. "And kelp forests, in turn, have all sorts of important functions.”
In the absence of sea otters, the ocean's kelp forest - which provides a habitat for fish and absorbs climate changing carbon emissions from the atmosphere - is left barren by sea urchins.
The kelp forests also provide habitat for fish and absorb climate changing carbon emissions from the atmosphere. Estes says this close connection between species health and the health of global ecosystems is a “ubiquitous phenomenon and that it occurs worldwide in all ecosystem types.”
Estes compiled the work of 24 scientists in six countries. He says the research shows the cascading ecological effects of a loss of top predators and large herbivores.
"It eventually reaches the plant populations at the base of the food web and in many instances results either in an increase in the abundance of plants or in most cases in terrestrial systems, a decrease in the abundance of plants, influencing things like fire frequency, carbon sequestration and disease and on and on and on.”
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