SS3.16 Lentic-Lotic Linkages in Freshwaters: Comparisons from Different Ecosystems
Date: Monday, June 10, 2002
Time: 4:45:00 PM
Location: Colwood
WurtsbaughWA, Utah State University, Logan, USA,
Baker, M, A, Utah State University, Logan, USA,
In alpine watersheds, lakes and streams are linked together in complex networks that influence processes ranging from nutrient transport to fish distribution. Analysis of the spatial distribution and morphometry of lakes and streams in the Sawtooth Mountains of Idaho provides insights on the importance of lake-stream interactions. The watersheds have between 1 and 25 lakes, and a mean inter-lake distance of 2.8 km. With a summer mean uptake length of 250 m, streams typically remove >99% of soluble phosphorus exported from a lake. Streams, however, have 76-86% of the total perimeter that interfaces with terrestrial and groundwater systems, and thus are collectors of nutrients. Between 77 and 99.8% of the water resides in lakes, with little in stream channels, and lakes thus increase water residence times >50-fold, and buffer nutrient transport. Lakes dominate water surface area (up to 94%) so that heating and primary production occur primarily in lakes: lakes located high in the watershed increase temperatures of stream channels throughout the drainage. The spatial patterning of streams and lakes is thus a crucial factor influencing ecosystem function.