Eutrophication of freshwater environments via anthropogenic phosphorus (P) input is one of the most serious global water management issues. To ameliorate such external P loading watershed-based management programmes are often implemented. However, many of these conservation schemes have failed to deliver improvements in water quality within predicted timescales. Invariably this is due to lakebed legacy P, the remobilisation of which to the overlying water column results in seasonal fluctuations in lake P levels which fuels algal growth. This internal P loading can thereby significantly delay the ecological recovery of eutrophic lake systems.
Modelling of the processes responsible for P-accumulation and release in lake sediments is largely based on a hypothesis proposed <75 years ago by Mortimer (1), which states that P release from bed sediments is tightly governed by redox conditions (the ‘geochemical P-pump hypothesis’). However, as early as 1988, Gächter et al., (2) - and others - noted that this geochemical hypothesis did not fully explain the observed decoupling of Fe- and P-liberation from bed sediments to bottom waters following the onset of reducing conditions in many lakes. This led to the ’microbial P-pump hypothesis’ that microbially-catalysed P-cycling significantly affects redox-sensitive P exchange at the sediment-water interface through regulation of a complex system of inorganic and organic P transformation processes. To date however this hypothesis remains largely untested in freshwater systems. This stands in contrast to our knowledge and greater understanding of microbial P cycling in marine systems (3).
The aim of this studentship will be to address this knowledge gap using a combination of in situ lake and laboratory (biogeochemical and molecular) methodologies to investigate microbial P cycling within Lough Leven (Kinross, Scotland: Loch Leven is the largest shallow eutrophic lake in lowland Scotland with over 40 years of monitoring data http://www.ceh.ac.uk/sci_programmes/water/loch-leven-case-study.htm
). The student, who will have the opportunity to work in Queen’s University Belfast, University of Aberdeen and at the Centre for Ecology and Hydrology (Edinburgh) will receive extensive training in a range of limnological, biogeochemical and molecular techniques (e.g. ion chromatography, NMR, molecular microbiology, ‘omics technologies and analytical biochemistry). As the results of this project will lead to a new understanding of the key biogeochemical processes acting to regulate P cycling in freshwater systems, peer review publications are anticipated. The student will also have the opportunity to liaise with catchment management groups, government regulators, industry, and nutrient management platforms [e.g. the European Sustainable Phosphorus Platform (https://www.phosphorusplatform.eu
), Irish Nutrient Sustainability Platform https://nutrientsustainability.ie)] as well as presenting their work at both national and international symposia (e.g. at Microbiology Society, International Society for Microbial Ecology, International Society of Limnology conferences).
1 October 2020
Candidates should have (or expect to achieve) a minimum of a 2.1 Honours degree in a relevant subject. Applicants with a minimum of a 2.2 Honours degree may be considered providing they have a Distinction at Master’s level.
• Apply for Degree of Doctor of Philosophy in Biological Sciences at Queen’s University Belfast
• State name of the lead supervisor as ‘Name of Proposed Supervisor’ on application
• State ‘QUADRAT DTP’ as Intended Source of Funding
• Select ‘Visit Website’ to apply now
1. Mortimer, C.H. (1941) J. Ecol. 29: 280
2. Gächter, R., Meyer, J. S., & Mares, A. (1988) Limnol. Oceanogr. 33: 1542
3. McGrath, J.W., Chin, J., & Quinn, J.P. (2013) Nat. Rev. Microbiol. 11: 412