In an extensive study, scientists from the University of Montana, University of California - Santa Cruz, and the University of California - Davis have shown that a top predator strongly affected plants and animals at the bottom of an island food web by eating organisms that transport nutrients between ecosystems. "An introduced predator alters Aleutian island plant communities by thwarting nutrient subsidies," is reported in the recent issue of Ecological Monographs.

As any biologist can attest, cells, organelles, and organisms maintain specific surface to area ratios to ensure life. Similar relations have been observed in regard to an island's size and nutrient deposition. In a number of cases, a small island with a large perimeter touching the sea receives more nutrients from marine ecosystems than a large island due to the differences in surface-to-area ratios. In a new study by John Maron, James Estes, Donald Croll, Eric Danner, Sarah Elmendorf, and Stacey Bucklelew, researchers have discovered that the introduction of a top predator has even affected this system.

"Our results show that the ecological effects of fox introductions extended well beyond the direct reductions of bird populations. We have clear evidence that foxes influence the terrestrial plant community and ecosystem dynamics through one particular route," state the scientists in their study.

The Aleutian archipelago has over 450 islands in the highly productive North Pacific Ocean and Bering Sea. In the harsh northern climate, the islands are covered in maritime tundra and nutrient-impoverished soil. With no native mammals, vast populations of seabirds (29 species currently) use the area for nesting. However, over the last 100-150 years, the introduction of arctic foxes and Norway rats (Rattus norvegicus) reduced the number of birds nesting on the islands.