The meromictic lakes and stratified marine basins of the Vestfold Hills, East Antarctica

Abstract

Thirty-four permanently stratified water bodies were identified in asurvey of the Vestfold Hills. Of these, 21 were lakes, six were seasonally isolated marine basins (SIMBs), and seven were marine basins with year round connection to the open ocean. The basins varied markedly in salinity (4 g I-' to 235 g 1-I), temperature (-14°C to 24"C), depth (5 m to 110 m), area (3.6 ha to 146 ha) and surface level (-30 m to 29 m above sea level).The stratification in all the basins was maintained by increases in salinity. During winter, a thermohaline convectidn cell was present in all lakes and SIMBs directly beneath the ice cover. These cells were the result of brine exclusion from the forming ice, and increased in density throughout winter, penetrating progressively deeper into the lake. Minimum stability, and therefore the maximum likelihood of turnover, occurred at the time of maximum ice formation in spring. At the end of the period of ice formation, the convection cell broke down, and stratification of the surface water occurred. When the ice melted completely, lenses of relatively fresh water capped the lakes, which reduced the effect of wind mixing. Net meltwater input increased the stability of the meromictic basins, while periods of lower water level resulted in deeper penetration of the thermohaline convection cell, increasing the possibility of turnover and destratification.

Ace Lake: three decades of research on a meromictic, Antarctic lake

“…Ace Lake has a maximum reported depth of between 23 and 25 m and an area of 0.13-0.18 km 2 (Hand and Burton 1981;Gibson 1999). It is fed by snow melt, which varies annually depending on the amount of precipitation.…”

“…The Vestfold Hills is a low-lying, ice-free coastal area of approximately 400 km 2 that contains around 300 lakes and ponds that range from freshwater, through hyposaline and saline, to hypersaline, formed in glacially scoured basins. Approximately 21 of the investigated saline lakes are meromictic having permanently stratified water columns with strong physical and chemical gradients (Gibson 1999). Ace Lake is one of these meromictic lakes and is also one of the most studied lakes in the Vestfold Hills; the lake has been a site of limnological investigation since the late 1970s (e.g.…”

An integrative study of a meromictic lake ecosystem in Antarctica

“…To achieve this goal, we chose to study a pristine, meromictic (permanently stratified) lake, Ace Lake (68.4731 S, 78.1891 E), located in the Vestfold Hills of East Antarctica (Supplementary Figure S1). Ace Lake was formed at the end of the Quaternary B12 000 years BP, and was initially fresh (Gibson, 1999;Rankin et al, 1999;Coolen et al, 2004Coolen et al, , 2006Cromer et al, 2005). Seawater invaded the lake basin during an early Holocene sea level highstand (B7000 years BP), and the lake was reformed after subsequent sea-level fall after B5000 years BP.…”

“…The lake is a structured, relatively closed system with marine-derived biota making it ideal for studying the short-term evolution of species and ecosystem function. A range of studies have described archaea, bacteria, eucarya and viruses in the lake, including several unusual bacteria, and the psychrophilic methanogens Methanogenium frigidum and Methanococcoides burtonii (Gibson, 1999;Rankin et al, 1999;Bowman et al, 2000;Coolen et al, 2004Coolen et al, , 2006Cromer et al, 2005;Laybourn-Parry et al, 2005;Madan et al, 2005;Powell et al, 2005;Cavicchioli, 2006;Allen et al, 2009). The lake is sensitive to climatic influences and is a sentinel for monitoring climate change.…”

Limnology and plankton diversity of salt lakes from Transylvanian Basin (Romania): A review

“…ursu lake was chosen as representative meromictic lake from the transylvanian basin. Hall, 1983;Hall and Northcote, 1986;Klepac-Ceraj et al, 2012;Organic Lake -Franzmann et al, 1987;Gibson, 1999;Yau et al, 2013;Ace Lake -Gibson, 1999;Rankin et al, 1999;Laybourn-Parry and Bell, 2014;Kaiike Lake -Matsuyama, 1977;Koizumi et al, 2004b;Ohkouchi et al, 2005;Shunet Lake -Degermendzhy et al, 2010;Baatar et al, 2016;Solar Lake -Cohen et al, 1977;Cytryn et al, 2000;Mono Lake -Jellison and Melack, 1993;Joye et al, 1999;Humayoun et al, 2003;Soap Lake -Walker, 1974;Oremland and Miller, 1993 extreme halophilic anaerobic microorganisms that derive energy from chemical reactions only. this picture was indeed, largely confirmed by the assessment of microbial diversity by culture-dependent and molecular techniques (see below).…”