HR: 09:45h
AN: NB21A-06 INVITED     [Abstracts]
TI: Summer-dry Streams in the Temperate Coastal Rainforest
AU: * Richardson, J S
EM: john.richardson@ubc.ca
AF: University of British Columbia, 3041 - 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
AB: Small streams of the temperate, coastal rainforest can go dry in summer and there is considerable annual variation in the extent of channel lacking surface flow. These small streams provide a special habitat for aquatic and riparian life, supplies of organic matter to downstream reaches, and modulate aspects of water quality. By late summer small streams regularly are reduced to a series of small pools, connected by subsurface flow. These stream beds are cool, but the small volume quickly heats up, potentially affecting downstream reaches. The effects on aquatic organisms are diverse, from isolating fish to maintenance of wetted substrates that support invertebrates. The effects of low flow periods can be persistent across seasons and some species recover slowly. Nevertheless, there are species of multivoltine macroinvertebrates that maintain populations in these systems. Small streams contribute substantial amounts of organic matter to downstream reaches, but most occurs during high flow periods, and not the low flow, warm periods when rates of biological processes are often at their highest. In the Pacific Northwest, many agencies struggle with how to balance the impact on these small streams with the resource values and opportunity costs associated with forest harvesting and other land-uses.
DE: 1845 Limnology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly