IN NEWS FROM the ol’ alma mater, it appears the sexual habits of salmon can move mountains.
A Washington State University researcher has found that salmon mating habits can alter the profile of stream beds, affecting the evolution of an entire watershed. His study is one of the first to quantitatively show that salmon can influence the shape of the land.
Alex Fremier, lead author of the study and associate professor in the WSU School of the Environment, said female salmon “fluff” soil and gravel on a river bottom as they prepare their nests, or redds. The stream gravel is then more easily removed by flooding, which opens the underlying bedrock to erosion.
“The salmon aren’t just moving sediment,” Fremier said in an interview with WSU News’ Eric Sorenson. “They’re changing the character of the stream bed, so when there are floods, the gravel is more mobile.”
The study, “Sex that moves mountains: The influence of spawning fish on river profiles over geologic timescales,” appears in the journal Geomorphology.
Working with colleagues at the University of Idaho and Indiana University, Fremier modeled the changes over 5 million years and saw streams with spawning salmon lowering stream slopes and elevation over time. Land alongside the stream can also get steeper and more prone to erosion.
“Any lowering of the streambed translates upstream to lower the entire landscape,” said Fremier.
Different salmon species can have different effects, Fremier said. Chinook, the largest salmon species, can move bigger pieces of material, while coho tend to move finer material. These differences can produce different erosion rates and landscape changes over time.
Fremier’s findings are another way of looking at the role of living things in shaping their nonliving surroundings. Trees prevent landslides; beavers build dams that slow water, creating wetlands, flood plains and habitats for different trees and animals.
In 2012, researchers writing in Nature Geoscience described how, before the arrival of trees more than 300 million years ago, landscapes featured broad, shallow rivers and streams with easily eroded banks. But tree roots stabilized river banks and created narrow, fixed channels and vegetated islands, while log jams helped create the formation of new channels. The new landscape in turn led to “an increasingly diverse array of organisms,” the researchers wrote.
Similarly, said Fremier, salmon can be creating new stream habitats that encourage the rise of new salmon species. On the other hand, streams where salmon drop in number or disappear altogether could see significant long-term changes in their profile and ecology.
“The evolution of a watershed can be influenced by the evolution of a species,” Fremier said.
Anglers meet in PT
Puget Sound/Strait of Juan de Fuca recreational fishing sampling manager Ann Stephenson will speak at Tuesday’s meeting of the the East Jefferson Chapter of Puget Sound Anglers.
The meeting will be held in the Port of Port Townsend Commissioners Office, 333 Benedict St..
Fish stories begin at 6:30 p.m., with the presentation following at 7 p.m.
Refreshments will be served. The public is invited to attend.
Jamestown S’Klallam Tribe Environmental Planning Program Manager Robert Knapp will speak at Thursday’s meeting of the North Olympic Peninsula Chapter of Puget Sound Anglers.
Knapp has been with the tribe for more than five years, first as a planner and now as manager. He works with landowners along the Dungeness River to conserve and restore salmon habitat. He will talk about the progress made and what the plans are for the future.
The meeting will be held at Trinity United Methodist Church, 100 S. Blake Ave.
The evening begins at 6:30 p.m. for viewing of raffle prizes and fish stories.
A short club business meeting begins at 7 p.m. and includes fishing reports from members, followed by Knapp.
A raffle of fishing gear will be held, as well as a membership drawing (must be present).
Refreshments will be served and the public is welcome.