11 - Diatoms as indicators of environmental change in antarctic freshwaters

Summary

Introduction

The Antarctic continent holds the majority of the earth's freshwater in the form of ice. However, life is dependent upon liquid water, which is scarce in Antarctica. Less than 5% of the continent is ice-free, and it is within these ice-free regions that freshwater lakes and ephemeral streams form by the melting of glacial ice. Ice-free regions are located primarily near the Antarctic coastline (Fig. 11.1). Of these regions, the ‘desert oases’ of East Antarctica are considered to be the coldest, driest regions on earth.

Within the limited sites where liquid freshwater is found, life is present. Cyanobacteria are the most widely distributed and abundant freshwater organisms, forming mats in lakes, ponds, and meltwater streams and on moist soils. Higher plants occur only in lower latitudes of the Antarctic Peninsula. Diatoms are found in nearly all types of Antarctic waters, and are one of few organisms that are well preserved as fossils. In this chapter, we review the investigations to date in Antarctica concerning the application of diatoms to problems of environmental change.

Antarctic diatoms

The study of freshwater algae in Antarctica began with early expeditions to the most accessible subantarctic and maritime islands of Kerguelen and South Georgia (Reinsch, 1890; Carlson, 1913). The flora of Kerguelen has been the most studied of any of the Antarctic regions (Bourrelly & Manguin, 1954; Germain & Le Cohu, 1981; Le Cohu, 1981; Le Cohu & Maillard, 1983, 1986; Riaux-Gobin, 1994).