Limnology and biology of saline lakes in the Rauer Islands, eastern Antarctica
The Rauer Islands contain more than fifty shallow lakes and small ephemeral ponds. Despite their
proximity to the Vestfold fills - one of the most diverse and intensively studied lake districts of eastern
Antarctica -the lakes of the Rauer Islands have remained undescribed. In this study the physical and chemical
limnology and biology of ten lakes is presented and their species-environment relationships explored using
multivariate statistics. Analyses of chemical and biological data indicate that the Rauer Islands form a distinct
limnological province amongst the lakes of the Pry& Bay oases. Salinities range from hypo- to hyper-saline
with an ionic order close to that of seawater. Deviance from this order indicates either an earlier origin for some
of the most hypersaline lakes when compared with the Vestfold Hills, more rapid evaporation vs precipitation
or differences in the sources of ions resulting from isostatic history. With fluctuating salinities, winter water
temperatures below -lO°C, seasonal ice and slush formation, desiccation and high levels of solar radiation, the
lacustrine environment presents considerable abiotic challenges for biological survival. Results indicate that
there is little or no planktonic flora in the lakes and no zooplankton were encountered. Despite this, analyses
of pigments, diatoms and other micro-algae revealed an active and diverse benthic biota characterized by
filamentous cyanobacteria with interstitial algae. Thirty-eight diatom taxa, and a selection of Chlorophyta and
Xanthophyta were detected amongst the cyanobacteria. Clusters in the diatom data correspond to salinity.
Further analyses of the relationships between the biota and their environment revealed some of the strategies
employed for survival. In particular, the synthesis of scytonemin was detected. This pigment is known to
function as an extracellular UV sunscreen which protects cyanobacterial cells against damage by ultraviolet
radiation. These results support the hypothesis that environmental extremes and biogeographical isolation
control the biology of these lakes.
Authors: Hodgson, D. ORCID record for D. Hodgson, Vyverman, W., Sabbe, K.