Biofilms in hypersaline shallow lakes are exposed to extreme conditions of water scarcity. To cope with stressors, microorganisms develop protection structures like a matrix of extracellular polymeric substances (EPS). Understanding EPS in these naturally-stressed habitats is key to predict how climate change may affect some ecosystems. This study focuses on how drought affects the structural properties of the EPS from hypersaline lakes. Chiprana and La Muerte are two hypersaline lakes in NE Spain that naturally dry out during summer. Biofilm samples were taken when they had surface water (wet treatment) and half of the samples were left to dry out for 45 days (dry treatment). Glycoconjugate patterns within the EPS were studied by Fluorescent Lectin Binding Analysis (FLBA) with Laser Scanning Microscopy (LSM). Structural patterns of the stained glycoconjugates were classified as associated to: cyanobacteria, bacterial clusters, filaments, and a cloud-like shape. Differences between sites were higher than differences between treatments. Specifically, higher glycoconjugates volume and cloud-like shaped EPS, and lower EPS associated to bacteria and filaments in La Muerte compared to Chiprana could be explained by environmental differences (e.g. Chiprana receives water from a permanent lake) that may result in distinct microbial communities inhabiting each lake and so different proportions in the EPS patterns. Differences between wet and dry treatments were minimal and only detected in Chiprana, showing the high resilience potential of these biofilms towards drought.

Primary Presenter: Judit Boadella, University of Girona (judit.boadella@udg.edu)

Authors:

Judit Boadella, GRECO, Institute of Aquatic Ecology, University of Girona  (judit.boadella@udg.edu)

Anna Romaní, GRECO, Institute of Aquatic Ecology, University of Girona  (anna.romani@udg.edu)

Thomas Neu, Helmholtz Center for Environmental Research - UFZ, Department of River Ecology  (thomas.neu@ufz.de)

Markus Weitere, Helmholtz Center for Environmental Research - UFZ, Department of River Ecology  (markus.weitere@ufz.de)

Núria Perujo, Helmholtz Center for Environmental Research - UFZ, Department of River Ecology  (nuria.perujo-buxeda@ufz.de)