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Professor Marian Yallop

Aquatic Microbiology and Ecosystem Change

In my research group we work on various aspects of the structure and functioning of freshwater, estuarine and marine ecosystems with a particular focus on microbial ecology.  Algae and cyanobacteria occupy a pivotal position at the base of many food chains. However, dominance by particular species can also be detrimental.  Of particular interest are those species living in extreme conditions, often termed extremophiles such as those living in highly polluted waterbodies, or those existing at extremes of temperature and pH.  We seek to understand the factors that lead to dominance and bloom formation of certain species, whilst also gaining insight into methods for controlling their growth where required.

Topics currently being pursued include:


  • Microbial community succession and metabolic pathways from ice to vegetated soils in response to glacial retreat

  • The role of ice algae in ice sheet melt in Greenland.
  • Impacts of ocean acidifcation on coralline algae

  • Taste and ddours in drinking water reservoirs

  • Ecotoxicology: impacts of anthropogenic stressors including heavy metals, pesticides and nanoparticles on the structure and functioning of biota in aquatic ecosystems.  

  • Using benthic diatoms to develop a predictive tool to measure ecological status in rivers and lakes

  • Control of cyanobacteria in drinking water reservoirs


Clear water macrophyte dominated lake


Research keywords

  • Ecotoxicology
  • Biofilms
  • Phytoplankton
  • Photophysiology
  • Nanoparticles
  • Pesticides
  • Extremophiles

Research findings

I recently found blooms of green algae carving out an existence directly on the surface of the Greenland Ice Sheet. Photophysiological measurements indicate that the ice algae likely use screeing mechanisms to downregulate photosynthesis when exposed to high levels of irradiance and UVR. These extremophiles through their photophysiology, likely play an important role in changing albedo and may impact melt rates on the ice sheet.