ECOSYSTEM SIZE, BUT NOT DISTURBANCE, DETERMINES FOOD-CHAIN LENGTH ON ISLANDS OF THE BAHAMAS

Gaku Takimoto; David A Spiller; David M Post

doi:10.1890/07-1990.1

ECOSYSTEM SIZE, BUT NOT DISTURBANCE, DETERMINES FOOD-CHAIN LENGTH ON ISLANDS OF THE BAHAMAS

Ecology. 2008 Nov;89(11):3001-3007. doi: 10.1890/07-1990.1.

Authors

Gaku Takimoto^{1

2}, David A Spiller³, David M Post²

Affiliations

¹ Department of Biology, Faculty of Science, Toho University, Funabashi, Chiba 274-8510 Japan.
² Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06511 USA.
³ Section of Evolution and Ecology, One Shields Avenue, University of California, Davis, California 95616-8755 USA.

PMID: 31766806
DOI: 10.1890/07-1990.1

Abstract

Ecologists have long struggled to explain variation in food-chain length among natural ecosystems. Food-chain length is predicted to be shorter in ecosystems subjected to greater disturbance because longer chains are theoretically less resilient to perturbation. Moreover, food-chain length is expected to be longer in larger ecosystems because increasing ecosystem size increases species richness and stabilizes predator-prey interactions, or increases total resource availability. Here we test the roles of disturbance and ecosystem size in determining the food-chain length of terrestrial food webs on Bahamian islands. We found that disturbance affected the identity of top predators, but did not change food-chain length because alternative top predators occupied similar trophic positions. On the other hand, a 10⁶ -fold increase in ecosystem size elevated food-chain length by one trophic level. We suggest that the effect of disturbance on food-chain length is weak when alternate top predators are trophic omnivores and have similar trophic positions. This and previous work in lakes suggest that ecosystem size may be a strong determinant of food-chain length in both aquatic and terrestrial ecosystems.

Keywords: Anolis lizards; Bahamian islands; disturbance; ecosystem size; food web; food-chain length; omnivory; orb spiders; predation; stable isotope; trophic position.