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Fjord benthic biogeochemistry and ecology in response to environmental change in NE Greenland

Dr Clare Woulds (SoG), Dr Jonathan Carrivick (SoG), Dr ANdrew Sweetman (Lyell Centre, Herriot-Watt)

Contact email: c.woulds@leeds.ac.uk

Project Summary

The seafloor is a key part of the marine system, providing important ecosystem services including C sequestration, biodiversity, and nutrient regeneration, as well as increasingly coming under pressure as a location for resource extraction and renewable energy infrastructure. Burial of organic C (OC) in marine sediments is a major mechanism for long-term C sequestration (Berner, 1982), and this is largely regulated by benthic biological activity. In turn, faunal communities are often structured by food supply, and their bioturbation, irrigation and digestion activities influence sedimentary OC standing stock and reactivity. These complex interactions between environmental and ecological factors inhibit predictions of how benthic biogeochemical cycling and C burial will respond to climate change in the arctic.

Fjords are long, deep estuaries carved by glaciers. In the arctic they are ecologically important, hosting distinctive benthic communities, and providing feeding and breeding grounds for megafauna (Lyderson et al., 2014). In addition, they exhibit disproportionately high rates of sediment carbon burial. Globally, fjord C burial is thought to amount to 18 Mt y-1, 11% of the global marine total, and the burial rate is approximately double the mean value for all other marine benthic settings (Smith et al., 2015). However, due to challenging access, relatively little is known about fjord benthic biogeochemistry and ecosystem function. 

Arctic fjords are currently subject to rapid environmental change. In addition to warming, melting and recession of their associated glaciers is increasing fluxes of freshwater, sediment, nutrients, and terrestrial organic matter into fjords. Increases in glacial sediment fluxes have been shown to impose burial stress on benthic communities, with detrimental impacts on their abundance and diversity (Wlodarska-Kowalczuk et al., 2005). Increases in the length of the ice free period are being shown to increase water column productivity, and this may increase C burial fluxes (Sorensen et al., 2015), but the effect of glacial meltwater inputs on the fjord ecosystem varies, depending on whether the glacier terminates on land or at sea (Meire et al., 2017). Thus, relatively little is known about the fate of glacial sediment, nutrients and organic matter, or their impacts on benthic ecosystem function (e.g. bioturbation, C-cycling), and biogeochemistry (e.g. nutrient fluxes).

Project Goals and Outline

This project will address the overarching question: how does marine benthic biogeochemical functioning respond to climate change conditions is Greenland fjords?

The project will take a combined observational and experiments approach, using sediment core incubations to measure functions including bioturbation, bioirrigation, and nutrient re-cycling, and employing experimental manipulations to investigate how these will respond to future conditions.

Skills and Training and Student profile

The successful candidate will benefit from an interdisciplinary outlook gained from working within the River Basins Processes and Management research cluster within the School of Geography, and from visiting the Lyell Centre, Herriot-Watt. They will also have access to the networks and event provided by water@leeds, and the Leeds NERC DTP. The successful candidate will become skilled at working at the interface of marine biology/ecology and geochemistry. They will gain experience in conducting marine benthic sampling and experimentation, and in designing and building bespoke equipment. They will also be trained in a wide range of laboratory analytical techniques, ranging from nutrient analysis to preparation of samples for both bulk and compound-specific stable isotopic analysis. Further, they are likely to undergo training in identification of benthic infauna.

An additional part of the training will be through attendance and presenting at national and international conferences. The student will also be encouraged to submit high quality papers for publication throughout the project, and this is supported at the institutional level by the availability of the option to submit the PhD thesis in an alternative ‘thesis by publication’ format.

Student profile

The successful candidate will have a degree in Environmental Science, Marine Science, Earth Science, Biological Science, or Physical geography, and exceptional motivation for postgraduate research. Masters degrees and previous research experience are advantageous.

Enquiries

Informal enquiries should be directed to Clare Woulds at c.woulds@leeds.ac.uk.
Enquiries relating to the application process and funding can be sent to Jacqui Manton (j.manton@leeds.ac.uk).

References

Berner, R. A.: BURIAL OF ORGANIC-CARBON AND PYRITE SULFUR IN THE MODERN OCEAN - ITS GEOCHEMICAL AND ENVIRONMENTAL SIGNIFICANCE, American Journal of Science, 282, 451-473, 1982.

Lydersen, C., Assmy, P., Falk-Petersen, S., Kohler, J., Kovacs, K. M., Reigstad, M., Steen, H., Strom, H., Sundfjord, A., Varpe, O., Walczowski, W., Weslawski, J. M., and Zajaczkowski, M.: The importance of tidewater glaciers for marine mammals and seabirds in Svalbard, Norway, J. Mar. Syst., 129, 452-471, 2014.

Meire, L., Mortensen, J., Meire, P., Juul-Pedersen, T., Sejr, M., Rysgaard, S., Nygaard, R., Huybrechts, P., and Meysman, F.: Marineā€terminating glaciers sustain high productivity in Greenland fjords, 2017.

Smith, R. W., Bianchi, T. S., Allison, M., Savage, C., and Galy, V.: High rates of organic carbon burial in fjord sediments globally, Nat. Geosci., 8, 450-U446, 2015.

Sørensen, H., Meire, L., Juul-Pedersen, T., de Stigter, H. C., Meysman, F., Rysgaard, S., Thamdrup, B., and Glud, R.: Seasonal carbon cycling in a Greenlandic fjord: An integrated pelagic and benthic study, 2015.

Wlodarska-Kowalczuk, M., Pearson, T. H., and Kendall, M. A.: Benthic response to chronic natural physical disturbance by glacial sedimentation in an Arctic fjord, Marine Ecology Progress Series, 303, 31-41, 2005.

Related undergraduate subjects:

  • Biology
  • Earth science
  • Earth system science
  • Ecology
  • Environmental science
  • Geochemistry
  • Geography
  • Geological science
  • Geology
  • Geoscience
  • Natural sciences
  • Oceanography
  • Physical geography