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CNR: Alamanacco della Scienza


N. 10 - 15 set 2010
ISSN 2037-4801

International info   a cura di Cecilia Migali


The deep zone of lakes, cradle of biodiversity  

De Long was the first, in 1992, to find - in marine coastal waters (North America) - micro-organisms of the domain archaea and therefore opened the way towards the research on planktonic archaea. In 2001 Karner highlighted how the deep waters of the Pacific Ocean might constitute an ecological niche where these micro-organisms outcompete bacteria.

In this framework, the research performed on lake Maggiore by the aquatic microbial ecology group leaded by Dr. Cristiana Callieri, active in the nineteenth-century villa where the Ise laboratories are located, advanced in the study of the ecology of inland waters. The Italian researchers found that, as in the sea, in the deep lakes alike archaea are present and active also at 350 meters, that is the maximum depth of lake Maggiore.

Archaea are micro-organisms capable of adaptations to extreme environmental conditions and, also in freshwaters, they can live at low temperatures (7°C) and high pressures (35 atm). The study of microbial diversity in the deep zone of the lake (hypolimnion) and the comparison with the more superficial zone where light is present (epilimnion), may open new perspectives for the understanding of the interactions among microbial species and of the metabolic processes at the base of the biogeochemical cycles in the aquatic ecosystems.

This subject of research attracted new collaborations with foreign limnologists (University of Zurich, Switzerland, and University of Comahue, Argentina) with the aim to extend the research on archaea to the North Alpine lakes and the North Patagonian Andine lakes. The outlooks of the research in the next years are addressed to isolate, as was done in the sea, organisms of a subgroup of archaea, the crenarchaea, which are capable of autotrophically oxidate ammonia and which hold a preeminent role (still much unknown) in the nitrogen cycle. The cooperation among different scientific groups might drive, using the know-how of each group, to the understanding of the role of crenarchaea and their origin. In the deep lakes the water mass of the hypolimnion contributes for more than 90% to total lake water mass and the study of biodiversity enclosed there is of paramount importance to preserve this water resource for the future.


Fonte: Cristiana Callieri, Istituto per lo studio degli ecosistemi, Pallanza Verbania, tel. + 39 0323 518321, email c.callieri@ise.cnr.it