The Microflora 263 



Algae 



Fifty-nine species of algae were found at Barrow. Blue-green algae 

 and bacteria are included in this figure as they are in the following discus- 

 sion of algae (Cameron et al. 1978). Green algae were represented by 35 

 species, diatoms by 12, blue-green algae by 7, euglenoids by 4, and 

 yellow-green algae by 1. The dominance of green and blue-green species 

 follows the pattern reported elsewhere in the tundra and in other Biomes 

 (John 1942, Taylor 1956, Durrell 1959, Dorogostaiskaya and Novich- 

 kova-Ivanova 1967, Gollerbakh and Shtina 1969, Akiyama 1970, Clark 

 and Paul 1970, Novichkova-Ivanova 1972). As with other flora and 

 faunal groups, the aquatic green and blue-green algae are more poorly 

 represented in the coastal tundra than they are farther south on the Arc- 

 tic Slope (Prescott 1953, Maruyama 1967). 



Prominent algal species include the green Chlamydomonas spp., 

 Chlorella vulgaris, Stichococcus bacillaris, Chlorococcum minutum and 

 Ulothrix subtilissima. A small Navicula sp. was the most frequently ob- 

 served diatom, and Schizothrix calcicola, a small oscillatorioid 

 blue-green form, was commonly cultured from many microtopographic 

 units. This latter species is probably the most common of the blue-green 

 algae in arctic tundra soils and appears cosmopolitan for it contributes a 

 large biomass in temperate, desert and grassland soils as well (Cameron 

 1972). Another of the blue-green algae, Nostoc commune, was found 

 frequently in a variety of microtopographic units. In the drier microtop- 

 ographic units it sometimes formed microscopic plants, but it developed 

 large, discrete mats in the moister units. This species is one that charac- 

 teristically dominates other nitrogen-fixing species in virgin soils with 

 moisture contents of 80 to 100<Vo dry weight (Shtina 1972). Thus its fre- 

 quent occurrence in polygon troughs and meadows is not unexpected. 

 Because it is less mobile in mat form, Nostoc tends to become parasitized 

 and lichenized in harsh environments, and in this climax form stabilizes 

 as Peltigera and Stereocaulon spp., which are more resistant to desic- 

 cation. 



Lemming fecal material is abundant in the upper soil, and several of 

 the common algal genera {Chlorella, Chlamydomonas, Scenedesmus, 

 Schizothrix and Elakatothrix) thrive in fecally contaminated habitats 

 (Doyle 1964). The algal flora documents another striking feature of the 

 tundra ecosystem — its high moisture levels. Several planktonic forms, in- 

 cluding Quadrigula lacustris and Scenedesmus quadricauda, were cul- 

 tured from wet meadows and polygon troughs. 



The absence of certain groups within cultures is equally noteworthy. 

 No desmids were encountered, although on the basis of observations in 

 other organic soils or polar regions they should be expected. Prescott 



