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Alpine river microbial community response to shrinking glaciers

Dr Lee Brown (SOG), Dr Alex Dumbrell (University of Essex), Dr Chris Hassall (SoB), Dr Pazit Ziv (water@leeds)

Contact email: l.brown@leeds.ac.uk

Project Description

Arctic and alpine zones will warm more and faster than all other parts of Earth to 2050 and beyond[1-4], causing widespread changes in snow and ice cover[5]. Changes will occur much more rapidly than other ecosystems due to the extremely high climatic sensitivity of glacier/snow pack mass balance and meltwater generation into rivers[6]. This PhD will quantify the implications of glacier shrinkage and retreat for river microbial communities. Microbial communities regulate the major global biogeochemical cycles and support entire food webs/ecosystems, but respond rapidly to environmental change. Yet most previous studies of biodiversity response to glacier retreat have focused principally on invertebrate larvae [7-10]. We can predict that it will be possible to generalise patterns of insect biodiversity loss with glacier shrinkage to microbial communities, although microbial richness might be higher due to diverse inputs (soil, ice, wind-blown, tributary) to rivers, even in heavily glacierized mountains that otherwise have low macrofaunal diversity[11]. We might also expect to see high turnover between putatively active and dormant taxa [11], so biofilm activity should also respond to glacier shrinkage.

Figure (L-R): Glacier fed rivers of the European Alps, Alaskan Coastal Range and New Zealand Alps

This PhD project will use river ecosystems as model systems because they have disproportionately high biodiversity compared to their coverage of Earth’s surface, they are especially sensitive to climate change particularly in cold zones, and are major players in global elemental cycles[12-14]. The PhD will use field-surveys with space-for-time substitution of catchment glacier cover to represent different stages of glacier retreat. A series of samples have already been collected and preserved from rivers of the Austrian Alps, French Pyrenees, Alaskan Coastal Range, Nepalese Himalayas and New Zealand Alps. The project will provide opportunities for the student to augment these samples with collections of their own from at least one other biogeographic locations (potentially Scandinavia, Greenland and/or Iceland). The central aim of the work will be to determine the composition and activity of microbial biofilms. There will also be opportunities to design and implement experiments to quantify the functional roles (e.g. primary production, respiration, nutrient uptake) of river biofilms.

Potential for high impact outcome

Sensitive mountain river systems are changing rapidly with climate change[4,6]. This is a major issue globally because the hydrological changes associated with glacier and snowpack loss are some of the greatest projected for any ecosystem, with major implications for society as well as riverine and near-shore marine ecosystems. In excess of 2 Billion people in Asia alone are heavily dependent on the ecosystem services provided by meltwaters, whilst Arctic and sub-arctic terrestrial zones alone contribute >3300km3 river runoff annually to northern oceans (equiv. to up to ⅔ of Amazon runoff). Meltwater rivers typically carry high sediment loads and deliver large quantities of dissolved and particulate nutrients to oceans. Increasing knowledge of microbial processes in these rivers is therefore vital to predicting changes to the flux, concentration and form of nutrients and organic matter exported from land to receiving lakes, coastal fjords and oceans[15], which in turn can have potentially profound feedbacks on climate[16].

Freshwater ecosystems are among the most threatened on the planet12: the Fifth IPCC report (17 p312) highlighted that "climate change will have significant additional impacts (high confidence), from altered thermal regimes, altered precipitation and flow regimes…", and that high latitude/altitude rivers are particularly at risk. Analyses of invertebrate communities in meltwater-fed rivers informed conclusions of the working group on Terrestrial and Inland Water Systems[17] with a prominent cross-chapter case study (CC-RF-2; see[8]). It is clear though from the 2014 IPCC report that there are still significant knowledge gaps as to how other groups of aquatic organisms will respond to altered meltwater regimes.

Training

The successful candidate will benefit from inter-disciplinary training in hydrology and aquatic ecology as part of the River Basin Processes and Management research cluster in the School of Geography, and as part of the wider water@leeds network (i.e. water@leeds: ecology group) and the Leeds NERC DTP. They will also benefit from training in microbiology and bioinformatics as part of the Dumbrell lab in the School of Biological Sciences, University of Essex. The Leeds Omics group also provides an opportunity to interact at multiple levels and in a virtual and physical environment with other researchers working on genomics and bioinformatics. The student will work with the supervisors to create a tailored training plan, but the nature of the project means there will be opportunities to be trained in remote location field skills and experimental design, and methods such as DNA extraction, PCR techniques, automated robotic sample preparation, next generation sequencing and bioinformatics on high-performance computers, river water quality analysis, measuring respiration in situ/with microcosm chambers, and applied statistics for analysing biological data. An additional important part of the training will be to attend national and international conferences to present results and gain feedback. The student will be encouraged to submit high quality papers for publication during the project, and to interact with non-academic groups for outreach and to generate societal impact.

Applicant profile

The student should have a strong interest in global environmental change, a strong background in biology/ecology and good familiarity with numerical data analysis. An ability to participate in remote location fieldwork (including being able to drive) is desirable.

References

[1] Duarte et al. 2012. Nature Clim. Ch. 2: 60;

[2] Anisimov et al. 2007. Polar regions in ref. 4;

[3]Vavrus et al. 2012. J. Climate 25: 2696;

[4] IPPC. 2007. Fourth Assessment Report of the IPCC. Cambridge University Press;

[5] Marzeion et al. 2014. The Cryosphere 6: 1295-1322;

[6] Barnett et al. 2005. Nature 438: 303;

[7] Brown et al. 2007. Glob. Ch. Biol. 13: 958;

[8] Jacobsen et al. 2012. Nature Clim. Ch. 2: 361;

[9] Cauvy-Fraunié et al. 2016. Nature Comms 7: 12025;

[10] Woodward et al. 2010. Glob. Ch. Biol. 16: 1979;

[11] Wilhelm et al. 2014. Env. Microbiol. 16: 2514;

[12] Vörösmarty et al. 2010. Nature 467: 555;

[13] Yvon-Durocher et al. 2010 Phil. Trans. Roy Soc B. 365: 2117;

[14] Woodward et al. 2010. Glob. Ch. Biol. 16: 1979;

[15] Torres-Valdez et al. 2013. JGR Oceans 118: 1625;

[16] Hood et al. 2009. Nature 462: 1044.

[17] Settele et al. 2014: Ch4 in IPCC 5th Assessment Report 271

Related undergraduate subjects:

  • Biology
  • Ecology
  • Environmental science
  • Microbiology
  • Physical geography