Experimental evidence that the topological features of microbial co-occurrence networks respond to stressors

Dr Annachiara Codello1, Professor Grant Hose1, Dr Frederic Boyer2, Dr Anthony Chariton1

1Macquarie University, Macquarie University, Australia, 2Université Grenoble Alpes, Grenoble, France

Abstract:

Microbial communities are now routinely used to assess and monitor aquatic ecosystems. However, microbes rarely live in insolation, and it is the collective of the community that drives many processes and helps maintain stability. Increasingly, co-occurrence networks are being used to examine how biotic interactions within microbial communities are altered by disturbances. However, with all but a few exceptions, these have been correlative, field-based studies; often producing ambiguous, and in some cases, disparate results. To address this,  we used a freshwater mesocosm experiment to: 1) examine whether the topological attributes of benthic microbial co-occurrence networks are altered by a stressor; and 2) determine if these attributes change in a concentration-dependent manner. The system consisted of 20 ponds spiked with five different concentrations of particulate copper (control, 46 mg/kg, 60 mg/kg, 257 mg/kg and 487 mg/kg). Networks were produced using two approaches, CoNet and SpiecEasi, and at two scales: individual pond level (replicated) and copper treatment level (pooled). We found that cluster coefficient, network density and characteristic path length were altered by the presence of copper, with degree centrality increasing with increasing copper concentrations. However, some metrics responded differently depending on the approach and/or scale. While our findings do add credence to the use of co-occurrence networks as a tool for assessing the responses of microbial communities to disturbances, we recommend that multiple approaches be used to produce the networks, with consideration also given to the influence of spatial scale and sample size.


Biography:

Dr Chariton is a Senior Lecturer and founder of the Environmental e(DNA) and Biomonitoring Lab, Macquarie University. Anthony is one of the early pioneers of environmental DNA metabarcoding, with his research focusing on the development, application and integration of ‘omic’ technologies and traditional ecology for the monitoring and assessment of coastal and marine environments. Specially, Anthony’s interest is in understanding how microbial and other benthic communities respond to both natural and anthropogenic stressors, as well as their interactions. His research captures a broad range of systems and scenarios, including developing routine monitoring tools for assessing the impacts of metals/metalloids and on tropical benthic communities and coral microbiomes. Dr Chariton’s other research interests include: groundwater ecology; functional ecology; biogeochemical cycling; terrestrial ecology; ecotoxicology; experimental design; and network analysis. He was a co-author for the revised Australian and New Zealand Sediment Quality Guidelines and former President of the Society of Environmental Chemistry and Toxicology (SETAC), Australasia.

Date

Mar 21 - 23 2022
Expired!