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LAKE PEND OREILLE, IDAHO - ATTACHED BENTHIC ALGAE (PERIPHYTON), 1986
Description:
Attached algae in the littoral zone of Pend Oreille Lake, a large deep meso-oligotrophic lake in northern Idaho (17010214) was studied for comparison to estimates of pelagic productivity. The study monitored periphyton growth rates during July and August 1986 on both artificial and natural substrate throughout the lake. Unglazed ceramic tiles were suspended at 0.5 m and 1.5 m depths and incubated for 30 days in mid-summer. Natural substrate means for all variables (trichromatic chlorophyll a, monochromatic chlorophyll a, dry weight, and ash-free dry weight) were higher than those of the artificial substrate. Means for all variables were higher on the 0.5 m tile than on the 1.5 m tile, however, exposed sites showed less difference between depths than did the more sheltered sites. Cymbella was the chief dominant on the natural substrate, while Cymbella, Mougeotia, and Rhizoclonium were equally dominant on the artificial substrates. Blue-green algae biomass comprised only a small part of the total biomass on either artificial or natural substrates. The data suggests accelerating eutrophication of Pend Oreille Lake. Algae growths are significantly greater in developed and relatively confined bays. Falter, C.M. 1987. Department of Fish and Wildlife Resources, University of Idaho, Moscow, ID. 32 pp. plus appendices.