Salmon & Dam Impacts Quiz
Pacific Northwest river ecology (10 questions).
Salmon & Dam Impacts Quiz: Quick Study Notes
The Pacific Northwest is a region defined by its stunning natural beauty, rich biodiversity, and vital river systems. Central to this ecosystem are salmon, anadromous fish species that undertake epic migrations from freshwater to the ocean and back to spawn. However, human development, particularly the construction of numerous dams for hydroelectric power and other uses, has profoundly altered these river environments, presenting significant challenges to salmon populations and the overall ecological balance.
Key Concepts
Key Takeaways
- Pacific Northwest rivers are critical habitats for diverse salmon species.
- Dams significantly impede salmon migration and alter river ecosystems through changes in water temperature, flow, and sediment.
- Hydroelectric power generation is a primary function of many PNW dams, creating a balance between energy needs and environmental impact.
- Salmon are anadromous fish, essential for nutrient cycling between marine and freshwater environments.
- Fish ladders and habitat restoration are key strategies for mitigating dam impacts and supporting salmon recovery.
- Indigenous cultures in the PNW have deep historical and ongoing connections to salmon.
Frequently Asked Questions
What does “anadromous” mean for salmon?
Anadromous fish, like salmon, are born in freshwater, migrate to the ocean to grow, and then return to their freshwater birthplaces to spawn and complete their life cycle.
How do dams specifically affect salmon migration?
Dams create physical barriers that block adult salmon from reaching their spawning grounds upstream and impede juvenile salmon (smolts) from migrating downstream to the ocean.
What are some alternatives or mitigation measures for dam impacts on salmon?
Mitigation measures include fish ladders, fish elevators, trap-and-haul operations, modified dam operations, and, in some cases, dam removal. Habitat restoration projects are also crucial.
Why are salmon so important to the Pacific Northwest ecosystem?
Salmon are a keystone species. When they die after spawning, their carcasses provide essential marine-derived nutrients to freshwater and riparian ecosystems, supporting insects, birds, mammals, and plant life.
Which major river in the Pacific Northwest is most affected by dams concerning salmon?
The Columbia River and its tributaries are among the most heavily dammed river systems in the world, significantly impacting its once-vast salmon runs.
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