Invisible world: the biogeography of molecular and microbial diversity in European lakes

Cambridge C-CLEAR NERC DTP PhD Studentship

Lead Supervisor: Andrew Tanentzap, Plant Sciences. Co-Supervisor: Thorsten Dittmar, University of Oldenburg.

Importance of the area of research concerned:

Dissolved organic matter (DOM) is central to the functioning of freshwater ecosystems that support Earth’s life systems. It does so by increasing the attenuation of solar radiation, altering contaminant toxicity and increasing nutrient pools. Changes in these properties result in major variation in ecosystem metabolism and production, particularly by freshwater microbes that live off DOM (Creed et al. 2018). Yet, despite its importance, little is known about how the vast diversity of molecules found in DOM influences its many properties. Recent advances in analytical chemistry have shown that a handful of lake water contains thousands of different molecular formulas of varying origin and composition (Kellerman et al. 2014). But the biological role of all these different molecules largely remains a mystery.

Project summary :

This project will discover how the composition of dissolved organic matter and microbial communities co-vary across macro-ecological scales. The first part of the project will borrow concepts from biodiversity to test how co-occurrence networks and properties of DOM and microbial communities change with lake and catchment characteristics. For example, the latitudinal diversity gradient predicts increasing species richness towards the Tropics, and here we will test this idea in communities of molecules and microbes. Relatedly, we will test how abundances of molecules differentially change with abundances of specific microbes and vice versa (Osterholz et al. 2016). The second part of this project will test how chemical diversity influences ecosystem multifunctionality in 25 British lakes, accounting for variation in microbial diversity.

What will the student do?:

The student will work with the ERC-funded project sEEIngDOM to mine existing data generated for 100 lakes spanning the extent of Continental Europe. They will employ the latest techniques in chemoinformatics and metagenomics. The student will also design a multi-year field study and collect all the associated data, working in remote locations in Scotland and northern England for long periods of time. Data collection will involve paddling to the middle of lakes and collecting water samples that will be analysed in the lab for chemical and microbial diversity. The student will then use statistical models to test how water chemistry and lake characteristics influence diversity.

References:

Kellerman, A.M., Dittmar, T., Kothawala, D.N. & Tranvik, L.J. 2014. Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology. Nature Communications, vol. 5, pp.3804., DOI 10.1038/ncomms4804

Creed, I.F. et al. 2018. Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes. Global Change Biology, vol. 24, pp.3692-3714., DOI 10.1111/gcb.14129

Osterholz., H., Singer, G., Wemheuer, B., Daniel, R., Simon, M., Niggemann, J. & Dittmar, T. 2016. Deciphering associations between dissolved organic molecules and bacterial communities in a pelagic marine system. ISME Journal, vol. 10, pp.1717–1730., DOI: 10.1038/ismej.2015.231

The deadline/closing date for applications is noon on Thursday 3rd January 2019. All supporting documentation including references must be submitted by this date. The project reference code is: BC041