Benthic algal biomass and productivity in high subarctic streams,Alaska |
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Authors: | Jacqueline D LaPerriere Erwin E Van Nieuwenhuyse Patricia R Anderson |
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Institution: | (1) Alaska Cooperative Fishery Research Unit, University of Alaska, 99775-0110 Fairbanks, AK;(2) Present address: School of Forestry, Fisheries and Wildlife, University of Missouri, 65201 Columbia, MO;(3) Present address: California Department of Fish and Game, 93940 Monterey, CA |
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Abstract: | Year-round measurements of the standing crop of epilithic algae (as chlorophyll a concentration) in two streams — one second and one fourth order (map scale 1:63 360) — in interior Alaska (64°–65° N) were only about one tenth that reported from streams of temperate North America. Cell densities in these streams, however, were similar to those in comparable temperate streams. Year-round domination of the benthic flora by very tiny diatoms (Achnanthes spp.) may explain the apparent disparity between low chlorophyll a content and nearly average cell densities. Chlorophyll a standing crop in a more alkaline groundwater-fed stream, however, was higher and within the range of similarly sized temperate streams. Maximum chlorophyll a standing crop varied positively with alkalinity in 5 clear-water streams where standing crop was measured on natural or artificial substrates. Seasonal mean concentrations of sestonic chlorophyll a (used as estimates of benthic algal chlorophyll a standing crop) varied directly and significantly with alkalinity among ten clear-water streams; and, with total phosphorus among 8 of 10 clear-water and 5 brown-water streams studied. During the summer, when there is little darkness, gross primary productivity (as estimated by the diurnal dissolved-oxygen method) was similar to that of northern temperate streams. Gross primary productivity was also seen to vary directly with alkalinity in 5 clear-water streams of this region.U.S. Fish and Wildlife Service |
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Keywords: | alkalinity benthic algae phosphorus primary productivity sestonic chlorophyll a standing crop |
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