Douglas Rasher

Douglas Rasher’s unique perspective and ability to formulate innovative hypotheses have led to important advances in understanding how ecological processes affect the structure and function of coastal ecosystems. His work is characterized by the breadth of nearshore ecosystems that he studies – from coral reefs in Fiji and Bonaire to kelp forests in Alaska and Maine – as well as his interdisciplinary approach to field biology. Most notably, Rasher has conducted detailed investigations of ecological interactions between macroalgae, herbivores and top predators, and how these interactions act to stabilize or destabilize such ecosystems.

In his work on Fijian coral reefs, Rasher established that competition for space between macroalgae and corals involves chemical warfare, wherein algae produce chemicals that poison corals. He also showed that herbivore diversity was very important in controlling macroalgae abundance on coral reefs since particular species of fish feed only on particular algae, a phenomenon mediated by chemicals produced by the algae. In another study he demonstrated that the foraging behaviors of herbivorous fishes were influenced by the tidal cycle, as they avoided times and places where predatory sharks were likely to be present. With this same emphasis on a mechanistic understanding of species interactions, Rasher has produced novel insights into the processes that now shape kelp forests across the Aleutian archipelago of Alaska. His field observations and experiments revealed that herbivores proliferated in the absence of predatory sea otters, and their grazing rates on coralline algal reefs have accelerated with ocean warming, beyond a tipping point.

Rasher is a super collaborator who has been the driving force behind studies that have changed our understanding of how complex and diverse ecosystems function. As a field biologist, he has repeatedly demonstrated the ability to conduct sophisticated chemical analyses and detailed experimental observations under challenging conditions.

For more information, visit www.bigelow.org/about/people/drasher.html