nghorn are declining throughout the basin.Climate varies greatly throughout the basin, depending upon elevations ranging from just above sea level to over 3,900 m. Annual precipitation can vary from about 25 cm to 250 cm. A common feature of the Columbia River Basin is the shrub-steppe ecosystem where moisture is scarce (coming mostly from snow in winter), the wind is persistent, and temperatures vary from 100F in summer to well below freezing in winter. Enzymes in an organism operate at an optimum temperature, and any deviation from this temperature 'norm' will result in below optimum respiration in the organism. All body temperatures in aquatic life vary directly with its environments. The health of aquatic ecosystems is critical to the entire Columbia River Basin. About 80 percent of all fish and wildlife in the basin use the streamside habitat at one time or another. Timber harvesting, livestock grazing, road construction, and mining have all dramatically changed aquatic ecosystems, affecting both water quality and quantity and altering water flows and temperatures. This, in turn, affects the types of wildlife, fish, and plants that can survive in the area. Salmon and other fish need aquatic habitat areas that are shaded and cooled by trees and protected with undercut banks vegetated by healthy grasses and sedges. The water should have plenty of woody debris where fish can hide and rest, as well as plenty of aquatic insects to eat. Not surprisingly, relatively untouched streams within wilderness or road-less areas tend to have the healthiest aquatic habitat conditions in the basin.As you can see, many factors will affect the overall existence of organisms in an ecosystem. The chemical and physical characteristics to begin with will determine which organisms are most likely to survive in the freshwater ecosystem. In turn, these pioneers entering the environment will actively manipulate these factors and change the schematics of the e...
