Algae from Alpine Areas in Rocky Mountain National Park, Colorado

Abstract

A collection of algae from alpine lakes (above 3000 m), principally desmids and diatoms, indicates oligotrophic, somewhat acid conditions. There have been few investigations of the algae of the central Rocky Mountain area of the United States. Shantz (1907) reported a few genera of the Pike's Peak area and Robbins (1912) published a preliminary list of Colorado algae. Olive (1955) reported a number of genera and named 35 species. In an excellent limnological study, Pennak (1955) listed 42 genera of algae, including several genera we have not found, and gave notes on their abundance as well as physical data from Bear Lake which we studied. Jones (nee Hallberg) (1937, 1932) reported some blue-green species. The only papers listing a sizable number of species are those of Miller (1936), who reported 112 species of desmids from the Medicine Bow Mountains (Wyoming); Durrell and Norton (1960), who listed 81 genera and 152 species from Grand Mesa; and Thomasson's (1964) paper on some lakes northwest of Denver which lists about 100 taxa. These are regions north and southwest of Rocky Mountain National Park. Stein and Amundsen (1967) reported a few species of snow algae from the Front Range south of the Park. Apparently there are few if any species so far reported from the Park. In early September 1969, one of us (L.A.W.) had the opportunity to collect 16 samples in the Park above 9000 ft (3000 m). Plankton collections were made with a No. 25 silk plankton net in Bear, Sheep and Poudre lakes. Littoral collections were made from the three lakes and a beaver pond near Horseshoe Park, from tundra pools, Iceberg Lake and a snowbank. Collections were kept refrigerated 48 hr until they could be examined fresh in our laboratory. All were then preserved in Transeau's solution and studied in more detail later. Permanent diatom slides were made, and all samples were deposited in the University herbarium. A total of 193 taxa representing 84 genera have been identified. Bear Lake is a small natural lake at 3200 m elevation in the east central part of the Park. It is in the evergreen forest and is about 150 X 100 m in size. Water temperature was 15 C and the pH near 6.5 (Pennak reports pH 6.3-6.7). Dinobryon cylindricum was abundant in the net collection; Ceratium hirundinella was moderately abundant, and Volvox aureus common. Among the 15 genera present were species of Asterionella, Melosira, Tabellaria, Peridinium and four desmids. The littoral zone was dominated by filamentous green algae in the genera Zygnema, Spirogyra, Mougeotia, Sphaerozosma and Bulbochaete. More than 30 other species were seen, mostly Chlorococcales,