Late quaternary climate history of Heart Lake and Pup Lagoon (Larsemann Hills, East Antarctica)

Information on East-Antarctic coastal environments during the Holocene is relatively sparse. This is surprising as sedimentary records from the interface between land and sea can provide chronologies of climate change, isostatic uplift, relative sea level and the colonisation of newly formed biomes. Here we examine a sediment core from Pup Lagoon and Heart Lake (Larsemann Hills, East Antarctica). Sediment stratigraphy, fossil pigments and diatoms were used to infer the sequence of Holocene environmental and climate change. Results show that between 5800 and 4785 corr. yr BP the marine coast of Prydz bay was characterized by stratified, open water conditions during spring and summer and seasonally warm conditions. From 4785 to 2615 corr. yr BP sea ice duration in Prydz Bay increased with the coast being ice-free for 2-3 months each year, conditions which are similar to the present day. A return to stratified, open water conditions and a reduction in winter sea ice extent between 2615 corr. yr BP - 2200 uncorr. yr BP is signaled by enhanced biogenic production and more open water diatom taxa

Conservation of diatom biodiversity: issues and prospects

The diatoms are microscopic unicellular plants, which in spite of their tiny size (normally within the range of 0.01-0.1 mm) play an enormous role in the functioning of the biosphere. Their contribution to the global production of organic matter created on Earth through photosynthesis is estimated as 20-25%. Very recently, the results of sensitive, fine-grained taxonomical, biological and biogeographical studies have provided strong evidence that the widely accepted dogma that microorganisms are predominantly cosmopolitan does not apply in case of the diatoms. Many diatom species may be endemics and some of them seem to be restricted to a small geographical area, which makes conservation of diatoms a significant issue. It is time to realise that efforts to develop realistic conservation strategies for aquatic environments, both at the local and global scale should include the diatoms and possibly also other groups of microorganisms. Some ways of how the diatoms could be involved in this process are presented for discussion

Organo-mineral imprints in fossil cyanobacterial mats of an Antarctic lake

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