McMurdo Dry Valleys Summer Phytoplankton Densities 1992-2001

 Phytoplankton were collected over four austral summers (1991-92 through1994-95) to examine seasonal and annual fluctuation in species composition and biovolume in Lakes Fryxell, Hoare, West Lake Bonney, and East Lake Bonney. All of these lakes are perennially ice-covered lakes located in the Dry Valleys of South Victoria Land, Antarctica.     The phytoplankton consisted primarily of cryptophyte and chlorophyte flagellates, and filamentous cyanobacteria. Some common taxa were vertically stratified (Oscillatoria limnetica, Phormidium angustissimum, Pyramimonas sp., Oscillatoria sp.), while others showed no distinct vertical stratification (Chlamydomonas subcaudata, Cryptomonas sp.). The stratification of the phytoplankton reflects the gradients of nutrients and light, and the stability of the water column.