Hydrological and biological regimes of lakes of East Antarctica

Abstract

Hydrological and biological regimes of different types of lakes of oases of East Antarctica, Thala Hills, Schirmacher Oasis and Larsemann Hills, were studied in the summer of 2010–2011. In lakes covered with ice, inverse temperature stratification is recorded. In the bottom layers of the water, the temperature (about 4 °C) is close to the values characteristic of water with a maximum density. Isothermy is observed on the opened small lakes, and water in some reservoirs warms up to 8 °С. Benthic communities of cyanobacteria and invertebrates are the main biological component of lakes, where there is no classical food chain and a microbial loop prevails. Studies have shown that a 3-meter layer of ice permits a sufficient amount of light even to a depth of 30 m. Light does not limit the development of algae and cyanobacteria. However, the low content of nutrients in the water limits the growth of phytoplankton, causing low values of biomass (less than 0.01 mg/l) and concentration of chlorophyll a (0.1–0.45 μg/l). A tendency to climate change around the Schirmacher oasis is recorded. In recent decades, some lakes, which in the middle of the last century were constantly covered with ice, began to open in the summer months. In the period when the lake is covered with ice, homothermy is established with a water temperature of 4 °C. After having opened, the water temperature in the lake drops to 0.5–1 °С because of wind-wave cooling.

Keywords

• antarctic lakes
• bottom communities
• phytoplankton
• chlorophyll
• climate change