. The Canadian field-naturalist. CHRYSOPHYTA. Figure 2. (1) Lagerheimia citriformis var. paucispina; (2) Lagerheimia quadriseta; (3) Pandorina morum; (4) Ulothrix subtilissima; (5) Aster- ionella fonnossa; (6) Tabellaria fenestrata; (7) Dinobryon sociale; (8) Dinobryon sertularia. Lac Philippe. Pink Lake with its alkaline waters, had no common desmid species and only 22 Chlorophyte taxa. The Chrysophyta dominated the water at Ramsay Lake in June with Cyanophyta being the second most abundant group. In July the Cyanophytes were still prominent and Chloro- phytes were found in wide variety. Duri
. The Canadian field-naturalist. CHRYSOPHYTA. Figure 2. (1) Lagerheimia citriformis var. paucispina; (2) Lagerheimia quadriseta; (3) Pandorina morum; (4) Ulothrix subtilissima; (5) Aster- ionella fonnossa; (6) Tabellaria fenestrata; (7) Dinobryon sociale; (8) Dinobryon sertularia. Lac Philippe. Pink Lake with its alkaline waters, had no common desmid species and only 22 Chlorophyte taxa. The Chrysophyta dominated the water at Ramsay Lake in June with Cyanophyta being the second most abundant group. In July the Cyanophytes were still prominent and Chloro- phytes were found in wide variety. During August, Cyanophytes were densest with the green and yellow-brown algae having a large variety of taxa but smaller numbers. Ramsay Lake has a smaller algal density ( cc cells/litre water) than either Lac Philippe () or Pink Lake (). The above values are mean densities calculated by summing the monthly densities (Figure 1) and dividing by 3. Ramsay shared with Meach Lake the following abundant species: Dino- bryon sociale in June; and Chrysosphaerella cf. longispina colonies in August. The high humic content of Ramsay Lake was reflected in its considerable turbidity (Fig- ure 1) and low Secchi transparency (Dickman and Peters, unpublished). The brown waters of this lake may inhibit algal growth through direct chemical inhibition as a result of the phenohc and humic substances dissolved in the water, by the absorption of necessary growth substances (nutrients) on humates, and by reduction in light penetration (Ruttner 1970). Dactylococcopsis sp. (Figure 6) was found above trace levels only in Meach and Ramsay Lakes. Ankistrodesmus cf. falcatus (Figure 3) was only in Ramsay as was A. cf. subulatus. Both are indicators of acid waters. The two bog lakes, Ramsay and Kidder, shared a num- ber of species such as Scenedesmus bijuga and Dinobryon vanhoeffenii and several species of the diatom genus Eunotia (Figure 3). Many of these shared species were acid-loving or a
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