Biodiversity 2 min

Biodiversity: microorganisms in lakes have been markedly impacted during the past century

PRESS RELEASE - Aquatic microorganisms are important actors in the ecosystems and biodiversity of lakes. However, we still have little understanding of the degree to which they have been affected by climatic and anthropogenic pressures. In a study published in Nature Communications on 31 July, a research team from INRAE, Université de Savoie Mont-Blanc, CNRS, Université Clermont-Auvergne and Université de Toulouse studied the DNA preserved in sediments from 48 lakes in order to compare the current diversity of microorganisms with that at the end of the 19th century, before the impact of human activities on ecosystems started to accelerate. Their results demonstrate drastic changes in the biodiversity of aquatic micro-organisms and a homogenisation of their diversity between lakes.

Published on 31 July 2020

illustration Biodiversity: microorganisms in lakes have been markedly impacted during the past century
© INRAE - Isabelle Domaizon

Between the 19th century and today occurred what is now referred to as the Great Acceleration, or in other words an intensification and rapid increase in the imprint of human activities on the environment.  Lakes are susceptible to these developments and to climatic pressures, but generally we still do not know the degree to which biodiversity has changed during the Anthropocene[1], and particularly for living microorganisms that are invisible to the naked eye.

Sediments: the archives of lakes

Dead microorganisms, or traces of their DNA, are preserved in the sediments that lie at the bottom of lakes. Successive deposits constitute a natural archive that can look back in time; by analysing the ancient DNA preserved in these deposits, scientists can reconstitute the microbial communities that were present in the lake at a given period. During the present study, the scientists compared the ancient DNA preserved in the sediments of 48 lakes in mainland France, focusing on the layers corresponding to the end of the 19th century with those covering the period 2000-2010 in order to reconstitute the evolution of lake biodiversity  over a hundred years.

Major changes to biodiversity and homogenisation of its composition

Analysis of this sedimentary DNA revealed major changes to the composition of the biodiversity of lowland lakes when compared with those at higher altitude (above 1400 m), which were less affected. Although the number of species present has not diminished, the composition in terms of species and species groups has evolved. The diversity of microalgae, parasites, saprotrophs[2] and micro-predators has undergone major changes, which have also been accompanied by a homogenisation of diversity between lakes: while in the 19th century, the different lakes displayed a highly diverse microbial composition, there has since been a standardisation of microbial biodiversity. And there have been some important winners: photosynthetic microorganisms have been favoured by climate warming and the input of nutrient elements due to human activities around lakes. 

This work throws new light on the changes to microbial diversity observed over long periods, at a time when microorganisms are not generally considered in important debates on biodiversity. From supplying drinking water to enabling numerous recreational activities and producing fish, lakes are sources of important ecosystem services to human societies that are influenced by microbial biodiversity. Greater efforts are now essential to monitor and preserve these ecosystems in a context of global change.

 

[1] The period which started with the Industrial Revolution when the impact of human activities on the environment started to intensify.

[2] Organisms that feed on dead organic matter.

 

Reference

Keck F, Millet L, Debroas D, Etienne D, Galop D, Rius D, Domaizon I., Assessing the response of micro-eukaryotic diversity to the Great Acceleration using lake sedimentary DNA, Nature Communications NCOMMS-20-07936, 31 July 2020 DOI: 10.1038\s41467-020-17682-8

 

INRAE Press Office

Scientific contact

Isabelle Domaizon Alpine Research Centre for Food Webs in Lentic Ecosystems

Centre

Division

Learn more

Biodiversity

Scott McCairns, an environmental explorer

When he discusses his career studying the ecological evolution of aquatic ecosystems, Scott McCairns, researcher at INRAE Brittany-Normandy, affirms that both luck, and timing, have been on his side. His recipe for success shines through his contagious enthusiasm: a curious scientific mind and a continual drive to expand his field of research.

21 December 2019

A new French-Chinese International Associated Laboratory dedicated to agroecology and green development

PRESS RELEASE - During the visit of a delegation from the China Agricultural University (CAU) to INRAE on 16 January 2020, INRAE’s Chair & CEO Philippe Mauguin and CAU’s Council President Peimin Jiang were the first to sign the agreement for the creation of a new International Associated Laboratory (LIA) dedicated to Agroecology and Agricultural Green Development (A-AGD).
This new LIA A-AGD aims to coordinate collaborative efforts between the CAU and French research institutes and universities. The goal is to achieve excellence in scientific research and support the transition towards a more sustainable and multiperformance model of agriculture, based on the principles of agroecology, both in the cereal plains of the north of China and in France.

16 January 2020

Biodiversity

Weed diversity mitigates crop yield losses

PRESS RELEASE - Scientists from INRA and the Scuola Superiore Sant’Anna (Italy) have shown that not all weed communities (spontaneous vegetation) generate crop yield losses, even in unweeded conditions, and that high weed diversity is associated to a reduced risk of important crop yield losses. Published in Nature Sustainability, these results provide new grounds for sustainable weed management.

19 December 2019