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Fluorescence of in vivo chlorophyll -q was also measured in each treatment. <br />In the laboratory the samples were washed through a 63 µm mesh screen to eliminate fine <br />silts and clays. Nematoda, Oligochaeta, Gastrotricha, Chironomidae, Ceratopogonidae, <br />Corixidae, Cladocera, Copepoda (adults, copepodites, and nauplii), and Rotifera were counted <br />using a dissecting microscope. All samples, both benthic and planktonic, from the three <br />treatments were counted for weeks 1, 3, and 5. Because of funding constraints the benthic <br />organisms from 10 randomly selected benthic samples were analyzed from weeks 2, 7, and 10. <br />Cladocerans and adult copepods from all sorted plankton samples were identified, as were <br />those collected in the ten benthic core samples. Chironomidae were mounted on slides in <br />Hoyer's solution and identified to genus using keys by Merritt and Cummins (1984), <br />Wiederholm (1983), and Mason (1968). Cladocerans and adult copepods were identified to <br />species using keys by Yeatman (1959), and Pennak (1989). <br />Statistical analysis <br />Densities from weeks 1, 3, and 5 were examined with analysis of variance (ANOVA) <br />tests. During week 7 we noted a significant reduction in permeability of the enclosure cages <br />caused by growth of algae on the screens. This introduced a potential bias when comparing <br />these areas with the open control sites for weeks 7 and 10 and for that reason these weeks <br />were excluded from the analysis, although data on benthic and planktonic densities are <br />provided for the control replicates so that seasonal trends can be observed (Tables 1 and 3). <br />We performed a weighted ANOVA on the treatment means (of sample counts) for each group <br />of organisms. The weighting was based on the number of samples processed for the mean. <br />The ANOVA model was: <br />4