Effects of the White River Ash Event and Climate Change on Aquatic Ecosystems in the Southwest Yukon

摘要

FRESHWATER LAKE ENVIRONMENTS ARE AFFECTED by disturbances on several scales that influence the composition of biological communities. A volcanic eruption is an abrupt and severe disturbance, and evidence of its impact is seen in lake sediments and soils as a layer of ash. These volcanic deposits affect aquatic ecosystems in lakes: large volumes of tephra can literally smother organisms living at the sediment-water interface (Edmondson, 1984), though the thinner layers of ash deposited farther from the source may have more subtle impacts. A less catastrophic, more gradual disturbance affecting aquatic ecosystems is climate change. Variations in temperature and precipitation over time indirectly influence the aquatic environment and have the potential to alter species composition and abundance (Rouse et al., 1997).