Content area
Full text
(ProQuest: ... denotes non-US-ASCII text omitted.)
Biological Sciences
Introduction
Wright Valley is a geographically diverse dry valley in southern Victoria Land, Antarctica. It contains the Onyx River (the largest and longest river in Antarctica), running inland (west) for 30 km from the Wright Lower Glacier and Lake Brownworth near the coast. The river is fed by streams draining from snowfields and alpine glaciers, mainly on the southern side of the valley. It terminates in the closed basin of Lake Vanda, which separates the eastern and western halves of the valley. Lake Vanda is perennially ice-covered, highly stratified, saline at depth and the site of a former small research station. The western half of the valley divides into the North and South Forks, both leading to the Labyrinth, an extensive system of bedrock channels below Wright Upper Glacier, which bounds the western end of Wright Valley.
Algae have been sporadically studied from Wright Valley. The first report appears to be that of Holm-Hansen (1964), who studied a single sample from each of Lake Vanda, an unnamed shallow pond and dry sand. Seaburg et al. (1979) carried out a more systematic study, sampling soils, plankton and benthic mats associated with Lakes Brownworth, Vanda and Canopus, and the Onyx River, and reported 15 species of cyanobacteria, 15 species of Chlorophyta and 14 species of Chrysophyta (in which they included diatoms). Other studies have included those on endolithic algae from Linnaeus Terrace (e.g. Darling et al. 1987), hypoliths (Cowan et al. 2010), benthic cyanobacterial mats from Lake Vanda (Hawes & Schwarz 2001), ponds (Wood et al. 2008b) and soils (Aislabie et al. 2006).
The taxonomic depth to which these organisms have been studied varies greatly. Knowledge of cyanobacteria that incorporates molecular data appears to be limited to automated ribosomal intergenic spacer analysis (ARISA) profiles (Wood et al. 2008b) and clone libraries (Aislabie et al. 2006, Cowan et al. 2010). Older studies from which identifications were based on morphology (Holm-Hansen 1964, Seaburg et al. 1979) may be vulnerable to the problem of convergent evolution of simple morphotypes, the identification and classification of which requires the incorporation of molecular data (Komárek 2012). In addition, type material is often inaccessible or non-existent. This...