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Biology of benthic algae in the unchannelized Missouri River
Abstract
A three year study of benthic algae of the unchannelized Missouri River was undertaken to determine the effects of diurnal water level fluctuations below hydroelectric dams on algal biomass, productivity, and community structure. The contribution of benthic algae to the particulate organic matter pool in suspension was also examined. A reduction of the epilithic algal biomass of up to 150-fold occurred in the presence of diurnal water level fluctuations. Rates of benthic primary productivity were also strongly depressed, and benthic algal community structure was altered and diversity reduced. The epilithic portion of the algal community was suppressed at an early successional stage. Without diurnal fluctuations, the climax epilithic algal community was dominated by the filamentous green alga, Cladophora glomerata, with its epiphytic diatoms. Frequent fluctuations also appeared to increase drift of benthic algae and aquatic macroinvertebrates in this system. Diurnal water level fluctuations functioned ecologically as a frequent disturbance or an acute stress to the benthic algal community in the Missouri River. Suspended benthic algae in the Missouri River contributed 0.2-0.6% of the total organic carbon; planktonic algae contributed 2.3-6.8%. Of the fine particulate organic carbon (FPOC) fraction, 7.2-21.8% resulted from autochthonous primary production. Dissolved organic carbon was 59% of the total organic matter in suspension. An average of 37.3% of coarse particulate organic matter (CPOM) was autochthonous in origin, with greater amounts produced in backwaters than at main channel sites. CPOM from allochthonous sources was more important at the main channel sites. Terrestrial plant matter was most abundant (59.9% of total CPOM), with benthic algae contributing an average of 3.7%. CPOM was relatively unimportant to the organic matter in suspension in the Missouri River, comprising 0.7% of the total.
Subject Area
Ecology
Recommended Citation
Carr, Jennifer Mae, "Biology of benthic algae in the unchannelized Missouri River" (1988). ETD collection for University of Nebraska-Lincoln. AAI8904480.
https://digitalcommons.unl.edu/dissertations/AAI8904480