Article (Scientific journals)
Salinity, depth and the structure and composition of microbial mats in continental Antarctic lakes
Sabbe, Koen; Hodgson, Dominic A.; Verleyen, Elie et al.
2004In Freshwater Biology, 49 (3), p. 296-319
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Keywords :
Antarctica; conductivity; cyanobacteria; diatom; microbial mat
Abstract :
[en] 1. Lakes and ponds in the Larsemann Hills and Bolingen Islands (East-Antarctica) were characterised by cyanobacteria-dominated, benthic microbial mats. A 56-lake dataset representing the limnological diversity among the more than 150 lakes and ponds in the region was developed to identify and quantify the abiotic conditions associated with cyanobacterial and diatom communities. 2. Limnological diversity in the lakes of the Larsemann Hills and Bolingen Islands was associated primarily with conductivity and conductivity-related variables (concentrations of major ions and alkalinity), and variation in lake morphometry (depth, catchment and lake area). Low concentrations of pigments, phosphate, nitrogen, DOC and TOC in the water column of most lakes suggest extremely low water column productivity and hence high water clarity, and may thus contribute to the ecological success of benthic microbial mats in this region. 3. Benthic communities consisted of prostrate and sometimes finely laminated mats, flake mats, epilithic and interstitial microbial mats. Mat physiognomy and carotenoid/chlorophyll ratios were strongly related to lake depth, but not to conductivity. 4. Morphological-taxonomic analyses revealed the presence of 26 diatom morphospecies and 33 cyanobacterial morphotypes. Mats of shallow lakes (interstitial and flake mats) and those of deeper lakes (prostrate mats) were characterised by different dominant cyanobacterial morphotypes. No relationship was found between the distribution of these morphotypes and conductivity. In contrast, variation in diatom species composition was strongly related to both lake depth and conductivity. Shallow ponds were mainly characterised by aerial diatoms (e.g. Diadesmis cf. perpusilla and Hantzschia spp.). In deep lakes, communities were dominated by Psammothidium abundans and Stauroforma inermis. Lakes with conductivities higher than +/-1.5 mS cm(-1) became susceptible to freezing out of salts and hence pronounced conductivity fluctuations. In these lakes P. abundans and S. inermis were replaced by Amphora veneta. Stomatocysts were important only in shallow freshwater lakes. 5. Ice cover influenced microbial mat structure and composition both directly by physical disturbance in shallow lakes and by influencing light availability in deeper lakes, as well as indirectly by generating conductivity increases and promoting the development of seasonal anoxia. 6. The relationships between diatom species composition and conductivity, and diatom species composition and depth, were statistically significant. Transfer functions based on these data can therefore be used in paleolimnological reconstruction to infer changes in the precipitation-evaporation balance in continental Antarctic lakes.
Disciplines :
Microbiology
Aquatic sciences & oceanology
Environmental sciences & ecology
Author, co-author :
Sabbe, Koen
Hodgson, Dominic A.
Verleyen, Elie
Taton, Arnaud
Wilmotte, Annick  ;  Université de Liège - ULiège > Département des sciences de la vie > Enzymologie
Vanhoutte, Koenraad
Vyverman, Wim
Language :
English
Title :
Salinity, depth and the structure and composition of microbial mats in continental Antarctic lakes
Publication date :
March 2004
Journal title :
Freshwater Biology
ISSN :
0046-5070
eISSN :
1365-2427
Publisher :
Blackwell Publishing Ltd, Oxford, United Kingdom
Volume :
49
Issue :
3
Pages :
296-319
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
MICROMAT
Funders :
UE - Union Européenne
Available on ORBi :
since 23 July 2009

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