And in years when salmon populations are high, sockeye dig up entire stream beds more than once, being forced to superimpose new nests on top of old nests when the females run out of room.
Moore's work and the UW's Alaska Salmon Program is funded by the National Science Foundation, the Gordon and Betty Moore Foundation and Alaska salmon processors.
The rototilling effect probably happens wherever salmon are found in high densities, such as British Columbia, Alaska and even some individual streams in the Pacific Northwest, Moore says. Kennedy Creek, for example, is a small stream that flows into south Puget Sound and since 1968 has had chum salmon in high-enough densities that they have caused the amount of algae and stream insects to decline.
Scientists have long known of the habitat-changing activities such as dam building by beavers, but much of ecology has assumed that most other organisms simply react to the physical and chemical conditions around them. A handful of papers since 1999, including one by Moore in 2004, has focused on the disturbance created by spawning salmon and the ecosystem at large. In this most recent paper, Moore also outlines a conceptual framework he's developed that gives ecologists a way to formulate when the abundance of animals and their activities ?be they spawning salmon or some other kind of animal ?make them impossible to ignore as ecosystem engineers.
"One specific application to stream restoration in the Pacific Northwest, for example, deals with the practice of fertilizing salmon streams with the carcasses of dead salmon obtained from hatcheries," says Daniel Schindler, UW associate professor of aquatic and fishery sciences. "Although this does replace some of the nutrients that salmon
Source:University of Washington