LIMNOLOGY OF ISOLATED AND CONNECTED HIGH-MOUNTAIN LAKES IN OLYMPIC NATIONAL-PARK, WASHINGTON-STATE, USA

High-mountain lakes in Olympic National Park, Washington State, USA, a re relatively small systems which become ice-free between late spring and mid-summer. A variety of lake types and environmental settings pro vided an opportunity to compare temporal changes in water quality and the structure and organization of plankton assemblages among seven lak es with different watershed characteristics and geographical positions . Two lakes were geographically isolated, while the others were connec ted by streams, forming a three-lake chain and two-lake chain in two d ifferent watersheds. The results supported the general hypothesis that the ecological properties of the lakes were closely related to their corresponding watershed characteristics and that biological similariti es among lakes were inversely related to differences in morphology, hy drology, geology, elevation and location. Most lakes exhibited increas es in temperature, alkalinity, conductivity and phytoplankton and zoop lankton densities between July and August. In general, temperature, al kalinity, conductivity, phytoplankton and zooplankton densities increa sed with decreasing elevation in the two groups of connected lakes. St ructure of phytoplankton assemblages was associated with lake depth an d nitrate concentration, while the distribution of crustacean zooplank ton corresponded to elevation and conductivity.