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Characterising microbial interactions that drive organic sulphur cycling in Antarctic waters

Project Member(s): Petrou, K., Seymour, J., Nielsen, D.

Funding or Partner Organisation: Australian Antarctic Division

Start year: 2015

Summary: Phytoplankton are critically important organisms in the Antarctic marine ecosystem, they form the base of the food-web and are the biological link that couples oceanic and atmospheric processes. While ocean warming is posing a serious challenge to all marine ecosystems, high latitude ecosystems are considered one of the most susceptible environments to its effects with significant implications for their biota and biogeochemical function. Ocean function is governed by microorganisms (bacteria and phytoplankton) whose activities and inter-species interactions are defined at the scale of individual cells. At this microscale, these interactions are frequently controlled by chemical signalling from phytoplankton. Demethylated sulphur compounds (dimethylsulphopropionate; DMSP and dimethyl sulphide; DMS) in particular have been recently recognised as potent drivers for these interactions in marine algae and corals. Given that many Antarctic phytoplankton species are large producers of these sulphur compounds for cryoprotection and osmoregulation, it follows that they may also play a key role in regulating phytoplankton-bacteria processes in the Antarctic marine environment. This project will examine how changes in environmental conditions (such as warming) affect sulphur production in these critically important primary producers and reveal how these altered metabolic processes influence the bacterial associations. Our team unites expertise in phytoplankton physiology, molecular microbial ecology and microscale experimentation to deliver new insights into understanding the ecological links between key Antarctic microbial populations. Combining novel concepts and techniques we will help predict the extent to which inter-species interactions and the biogeochemical functionality of the Antarctic marine microbial food-web may be altered in a changing ocean.

FOR Codes: Microbial Ecology, Biological Oceanography, Chemical Oceanography, Marine Oceanic Processes (excl. climate related), Marine Flora, Fauna and Biodiversity, Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts)