Dr Mark Ledger

Dr Mark Ledger

School of Geography, Earth and Environmental Sciences
Senior Lecturer in Ecology

Contact details

School of Geography, Earth and Environmental Sciences
University of Birmingham
B15 2TT

Mark is an ecologist researching environmental change in freshwaters. His research group is focused on understanding how environmental stressors and climate change, especially extreme climatic events such as floods, droughts and heat waves, affect the structure and functioning of aquatic ecosystems. His group works empirically across a range of spatial and temporal scales, from laboratory microcosms to natural environmental gradients in real ecosystems, and has developed new state-of-the-art mesocosm facilities which enable novel interdisciplinary experimental approaches to be applied in areas of water science usually characterised by phenomenological study. Mark currently leads several NERC-funded research projects and supports a number of doctoral researchers and postdoctoral fellows. He also works actively with a growing network of colleagues in the UK and overseas.


Mark read Biology at UCNW Bangor, graduating with a B.Sc. (Hons) in 1993, then joined the research group of Professor Alan Hildrew at Queen Mary and Westfield College, University of London. His Ph.D. research at QMW (completed 1997) investigated the relationship between acidification-induced biodiversity loss and ecosystem processes in upland streams. He was then awarded a Royal Society Fellowship to work with Professor Mike Winterbourn at the University of Canterbury, New Zealand, from 1998-1999. With Mike he worked on growth and trophic ecology of NZ stream invertebrates. Thereafter, he held a NERC-Freshwater Biological Association Pioneer Research Fellowship, based here in the School of Geography, Earth and Environmental Sciences in Birmingham (with Prof. Sandy Milner, 1999-2003). He was appointed to a Lectureship within the School in 2003, completed a Postgraduate Certificate in Learning and Teaching in 2008, and was promoted to Senior Lecturer in 2013. Mark serves on the NERC Peer Review College (UK) and is an Assessor for the Australian Research Council. He has served as Associate Editor for Ecology and Evolution, Guest Editor for Freshwater Biology, and Treasurer for the Aquatic Group of the British Ecological Society.


Mark has developed a broad teaching portfolio across the Geography and Environmental Science programmes, at both undergraduate and postgraduate levels. He teaches in the following areas:

  • Tutorials and fieldwork
  • Ecological systems
  • Techniques in physical geography
  • Research methods for dissertations
  • River ecology
  • Advances in water science
  • Research and management of rivers
  • River environmental management dissertation
  • Research project supervision
  • Freshwater environments

Postgraduate supervision


  1. Dr Rebecca Harris. Completed 2006. The effect of experimental drought disturbance on macro-invertebrate assemblages in stream mesocosms. Funded by NERC-FBA. M.E. Ledger (lead), A.M. Milner (UoB).
  2. Dr Helen Vincent. Completed 2009. Algae-herbivore interactions in stream food webs. Funded by NERC with CASE support from the Centre for Ecology and Hydrology. Dr M.E. Ledger (lead), Dr A.M. Milner (U of B) and Dr J. Murphy (CEH Dorset).
  3. Dr Jessica Frame. Completed 2010. Ecology of acidification and recovery in welsh upland streams. Funded by GEES with support from the Centre for Ecology and Hydrology. Dr. M.E. ledger (lead), Dr J.I. Jones (CEH Dorset), Prof S.J. Ormerod (Cardiff University) and Dr J.P. Sadler (U of B).
  4. Dr Katie Aspray. Completed 2012. Freshwater biodiversity and ecosystem function in changing moorland landscapes. NERC OPEN CASE studentship with CASE support from Natural England. Dr L.E. Brown (lead), Dr J. Holden (University of Leeds), Dr M.E. Ledger (UoB), Dr C.P. Mainstone (Natural England).
  5. Dr Ian Thornhill. Completed 2013. Water quality and biodiversity of urban ponds (funded by NERC with CASE support from the Macaulay Institute). M.E. Ledger (lead), Dr L. Batty (U of B) and Dr N. Friberg (the then Macaulay Institute).
  6. Dr Alex Poynter. Completed 2014. Impacts of environmental stressors on the River Itchen Ranunculus community. Environment Agency funded. L. Batty, J. Bridgeman, M.E. Ledger (UoB), S. Medgett (EA).
  7. Dr Robert Fowler. Completed 2015. Building for Biodiversity: managing and creating green infrastructure to maximise ecological services in our cities. EPSRC funded. J.P. Sadler (lead), M.E. Ledger & A. Bates (UoB).
  8. Caroline Mullen. Completed 2016. Biodiversity, species redundancy and ecosystem processes in a freshwater grazer assemblage: a functional approach. Centre for Ecology and Hydrology PhD Studentship. M.E. Ledger (lead), A.M. Milner (UoB), F. Edwards (CEH Wallingford).
  9. Svein Harald Sønderland. Completed 2016. Food web dynamics in recently de-glaciated terrain. Self-funded. A.M. Milner (lead), M.E. Ledger (UoB).
  10. Gavin Williams. Submitted 2016. Impact of extreme events on biodiversity-ecosystem functioning relationships in streams. NERC Project Student. M.E. Ledger (lead), L.Batty (UoB), M. Trimmer, G. Woodward (QMUL).    


  1. Eva Loza Vega (2014-) Long term changes in macroinvertebrate communities in streams of Denali National Park, Alaska. CONACYT, Consejo Nacional de Ciencia y Tecnología (Mexico) PhD Scholarship. A.M. Milner (lead), M.E. Ledger (UoB).
  2. Zining Wang (2014-) Drought impacts on stream ecosystems. Self-funded. M.E. Ledger (lead), A.M. Milner (UoB), S. Hayward (UoB).
  3. Thomas Aspin (2014-) Drought impacts on stream ecosystems. NERC CENTA Doctoral Training Partnership Studentship. M.E. Ledger (lead), A.M. Milner (UoB), F. Edwards (CEH), S. Hayward (UoB).


I am a member of the Water Sciences Research Group, and have recieved funding for following ongoing research projects:

Drought impacts on the structure and functioning of stream ecosystems (DRI-STREAM)

NERC Standard Grant, £701k

Climate change is expected to alter the quantity of water entering rivers and streams, with potentially devastating impacts on the structure and functioning of these ecosystems. This project (led by Mark Ledger, in collaboration with Mark Trimmer at QM and Guy Woodward at ICL) uses novel mesocosm experiments to understand the ecological effects of hydrologic droughts in streams, with a view to predicting future change. Read more about DRI-STREAM.  

NERC DRI-STREAM on Flickr                                                            

Hydrodynamics of microbial landscapes

NERC Standard Grant £750k

The way in which water flows across a surface is one of the most complex phenomena to model and predict accurately in the environment. This project (led by Greg Sambrook Smith, UoB) explores how microbes living in biofilms in freshwater environments influence the flow of water around substrate particles, with implications for biogeochemistry of natural systems and wastewater treatment.

Quantifying ecosystem resilience: catastrophic collapse and recovery of a large river food web

NERC Urgency Grant £65k

Mark is part of an interdisciplinary team investigating the ecological impact of a pesticide spill on the River Kennet. The project, which is funded by a NERC Urgency grant (led by Guy Woodward at ICL), takes a genes-to-ecosystems approach to establish the effect of the stressor across multiple levels of organisation. This unique case study will yield invaluable new insights into of the fragility and resilience of natural systems, and especially of how pesticide effects are felt far beyond those of their usual target organisms.

The effect of contrasting disturbance regimes on the architecture and functioning of freshwater food webs

NERC Small Grant £30k

Environmental perturbations can cause non-random species loss in ecological communities, altering the architecture and functioning of food webs. Research funded by a NERC small grant (Ledger and Milner CoPIs) revealed how stream drying caused by drought affected secondary production and energy flow through the food web. This ongoing research collaboration with Lee Brown (Leeds), Francois Edwards (CEH Wallingford) and Guy Woodward (ICL) has recently been published in Nature Climate Change (see below).

Developing the EcoLaboratory (Environmental Change Outdoor Laboratory) a large-scale experimental facility for interdisciplinary environmental science

University of Birmingham Dynamic Investment Fund (£1.2M)

The new ECOLAB facility (outdoor mesocosms with monitoring and analytical equipment and laboratory) feeds the urgent and rapidly growing international demand for transformative experimental facilities to address the grand environmental challenges of the future.


View project photos on Flickr

Other activities

  • Director, Birmingham ECOLAB facility
  • Programme Lead, Environmental Science
  • Treasurer, Aquatic Ecology Group of the British Ecological Society
  • Assessor, Australian Research Council
  • Member, Natural Environment Research Council Peer Review College
  • Associate Editor, Ecology and Evolution
  • Guest Editor, Freshwater Biology special issue: Extreme events in running waters


Key Publications

Aspin, T., Khamis, K., O’Callaghan, M.J., Milner, A.M. & Ledger, M.E. (2019) Drought intensification alters the composition, body size and trophic structure of invertebrate assemblages in a stream mesocosm experiment. Freshwater Biology. DOI: 10.1111/fwb.13259

Aspin TWH, Khamis K, Matthews TJ, Milner AM, Trimmer M, Woodward G & Ledger ME (2018) Extreme drought pushes stream invertebrate communities over functional thresholds. Global Change Biology. 00:1–15. DOI:10.1111/gcb.14495

Brown LE, Aspray KL & Ledger ME, Mainstone C, Palmer SM, Wilkes M & Holden J (2018). Sediment deposition from eroding peatlands alters headwater invertebrate biodiversity. Global Change Biology. 00:1–18. DOI:10.1111/gcb.14516

Thornhill, I., Biggs, J., Hill, M.J., Briers, R., Gledhill, D.H., Wood, P.J., Ledger, M.E., Hassall, C. (2018). The functional resilience of ponds along land-use intensity and environmental gradients. Global Change Biology. DOI: 10.1111/gcb.14149

Aspin TWH, Matthews TJ, Khamis K, Milner AM, Wang Z, Callaghan MJO, Ledger ME. (2018) Drought intensification drives turnover of structure and function in stream invertebrate communities. Ecography DOI: 10.1111/ecog.03711

Hill, M.J., Biggs, J., Thornhill, I., Briers, R.A., Ledger, M.E., Gledhill, D.H., Wood, P.J. & Hassall, C. (2018) Community heterogeneity of aquatic macroinvertebrates in urban ponds at a multi-city scale. Landscape Ecology, 33, 389-405.

Thornhill, I., Batty, L.C., Friberg, N., Ledger, M.E. (2018) The application of graph theory and percolation analysis for assessing change in the spatial configuration of pond networks. Urban Ecosystems, 21, 213-225.

Thornhill, I., Batty, L.C., Death, R.G., Friberg, N., Ledger, M.E. (2017) Local and regional determinants of invertebrate community structure in ponds across an urban land-use gradient. Biodiversity and Conservation, 26(5), 1065-1086.

Aspray, K.L., Holden, J., Ledger, M.E., Mainstone, C. & Brown, L.E. (2017) Organic sediment pulses impact rivers across multiple levels of ecological organisation. Ecohydrology. 10(6) UNSP e1855. DOI: 10.1002/eco.1855.

Lu X, Gray C, Brown LE, Ledger ME, Milner AM, Mondragón RJ, Woodward G. (2016) Drought rewires the cores of food webs. Nature Climate Change 6: 875–879. DOI: 10.1038/NCLIMATE3002

Khamis K, Brown LE, Hannah DM, Milner AM. (2014) Experimental evidence that predator range expansion modifies alpine stream community structure. Freshwater Science 34: 66–80.DOI: 10.1086/679484

Lu, X., Gray, C., Brown, L.E., Ledger, M.E., Milner, A.M., Mondragon, R., Woodward, G., Ma, A. (2016) Drought rewires the cores of food webs. Nature Climate Change, 6, 875–878.

Woodward, G., Bonada, N., Brown, L.E., Death, R.G., Durance, I., Hladyz, S., Ledger, M.E., Milner, A.M., Ormerod, S.J., Thompson, R.M. (2016) Extreme climatic events and their consequences for biodiversity, food webs and ecosystem properties in running waters. Philosophical Transactions of the Royal Society B: Biological Sciences, 371, doi: 10.1098/rstb.2015.0274.

Ledger, M.E. & Milner, A.M. (2015) Extreme events in running waters. Freshwater Biology, 60, 2455-2460.

Thompson, M. S. A., Bankier, C., Bell, T., Dumbrell, A. J., Gray, C., Ledger, M. E., Lehmann, K., McKew, B. A., Sayer, C.D., Shelley, F., Trimmer, M., Warren, S. L. and Woodward, G. (2015), Gene-to-ecosystem impacts of a catastrophic pesticide spill: testing a multilevel bioassessment approach in a river ecosystem. Freshwater Biology. doi: 10.1111/fwb.1267

Leigh, C., Bush, A., Harrison, E.T., Ho, S.S., Ledger, M.E., Luke, L., Rolls, R.J. (2015) Ecological effects of extreme climatic events on riverine ecosystems: insights from an Australian perspective. Freshwater Biology, 60, 2620–2638.

Lancaster, J. & Ledger, M.E. (2015) Population-level responses of stream invertebrates to drying can be density-independent or density-dependent. Freshwater Biology, 60, 2559–2570.

Stewart, R.I.A., Dossena, M., Bohan, D.A., Jeppesen, E., Kordas, R.L., Ledger, M.E., Meerhoff, M., Moss, B., Mulder, C., Shurin, J.B., Suttle, B., Thompson, R., Trimmer, M., Woodward, G. (2013). Mesocosm experiments in ecological climate change research. Advances in Ecological Research, 48, 71-181.

Ledger, M.E., Brown, L.E., Edwards, F.K., Hudson, L.N., Milner, A.M., Woodward, G. (2013). Extreme climatic events alter complex food webs: evidence from a mesocosm drought experiment. Advances in Ecological Research, 48, 343-395.

Ledger M.E., Brown L.E., Edwards F., Woodward G., Milner A.M. (2013) Drought impacts on the structure and functioning of complex food webs. Nature Climate Change, 3, 223-227.

Hudson, L.N., Emerson, R., Jenkins, G.B., Layer, K, Ledger, M.E., Pichler, D.E., Thompson, M.S.A, O'Gorman, E.J., Woodward, G., Reuman, D.C.  2013. Cheddar: analysis and visualisation of ecological communities in R. Methods in Ecology and Evolution, 4, 99-104.

Ledger, M.E., Brown, L.E., Edwards, F.K., Hudson, L.N., Milner, A.M., Woodward, G. (2013). Extreme climatic events alter complex food webs: evidence from a mesocosm drought experiment. Advances in Ecological Research, 48, 343-395.

Ledger M.E., Brown L.E., Edwards F., Woodward G., Milner A.M. (2013) Drought impacts on the structure and functioning of complex food webs. Nature Climate Change, 3, 223-227.

Ledger M.E., Harris R.M.L., Armitage P.D. & Milner, A.M. (2012). Climate change impacts on community resilience: experimental evidence from a drought disturbance experiment. Advances in Ecological Research, 46, 211-258.

Ledger M.E., Harris R.M.L., Armitage P.D. & Milner, A.M. (2012). Climate change impacts on community resilience: experimental evidence from a drought disturbance experiment. Advances in Ecological Research, 46, 211-258.

Hagen, M., Kissling, W.D., Rasmussen, C., De Aguiar, M.A.M, Brown, L.E., Carstensen, D.W., Alves-Dos-Santos, I., Dupont, Y.L., Edwards, F.K., Genini, J. Guimarães Jr., P.R., Jenkins, G.B., Jordano, P., Kaiser-Bunbury, C.N., Ledger, M.E., Maia, K.P., Flavia, M., Marquitti, D., Mclaughlin, O., Morellato, L.P.C., O’Gorman, E.J., Trøjelsgaard, K., Tylianakis, J.M., Morais Vidal, M., Woodward, G. & Olesen, J.M. (2012) Biodiversity, species interactions and ecological networks in a fragmented world. Advances in Ecological Research, 46, 89-210.

Woodward, G., Brown, L., Edwards, F.K., Hudson, L.N., Milner, A.M., Reuman, D.C. & Ledger, M.E. (2012). Climate change impacts in multispecies systems: drought alters food web size-structure in a field experiment. Philosophical Transactions of the Royal Society B, 367 (1605), 2990-2997.

Ledger, M.E., Edwards, F., Brown, L.E., Woodward, G. & Milner, A.M. (2011) Impact of simulated drought on ecosystem biomass production: an experimental test in stream mesocosms. Global Change Biology, 17, 2288-2297.

Brown, L.E., Edwards, F., Milner, A.M., Woodward, G & Ledger, M.E. (2011) Food web complexity and allometric scaling relationships in stream mesocosms: implications for experimentation. Journal of Animal Ecology, 80, 884-895.

Woodward, G., Benstead, J.P., Beveridge, O.S., Blanchard, J., Brey, T., Brown, L., Cross, W.F., Friberg, N., Ings, T.C., Jacob, U., Jennings, S., Ledger, M.E., Milner, A.M., Montoya, J.M., O'Gorman, E.O., Olesen, J.M., Petchey, O.L., Pichler, D.E., Reuman, D.C., Thompson, M.S., Van Veen, F.J.F., and Yvon-Durocher, G. (2010) Ecological networks in a changing climate. Advances in Ecological Research, 42, 71-138.

Ledger, M.E., Harris, R.M.L., Armitage, P.D. & Milner, A.M. (2009) Realism of model ecosystems: an evaluation of physicochemistry and macroinvertebrate assemblages in artificial streams. Hydrobiologia, 617, 91-99.

Ings, T.C., Montoya, J.M., Bascompte, J., Blüthgen, N., Brown, L., Dormann, C. F., Edwards, F., Figueroa, D., Jacob, U., Jones, J. I., Lauridsen, R. B., Ledger, M.E., Lewis, H.M., Olesen, J.M., Van Veen, F.F., Warren, P.H. & Woodward, G. (2009). Ecological networks – beyond food webs. Journal of Animal Ecology, 78: 253–269.

Ledger, M.E., Harris, R.M.L., Armitage, P.D. & Milner, A.M.M. (2008) Disturbance frequency influences patch dynamics in stream benthic algal communities. Oecologia, 155, 809-819.

Harris, R.M.L., Milner, A.M.M., Armitage, P.D. & Ledger, M.E. (2007) Replicability of biodiversity and physicochemistry in stream mesocosms: implications for experimental research. Freshwater Biology, 52, 2434–2443.

Ledger, M.E., Harris, R.M.L, Milner, A.M.M. & Armitage, P.D. (2006) Disturbance, biological legacies and community development in stream mesocosms. Oecologia, 148, 682-691.

Brose, U., Jonsson, T., Berlow, E.L., Warren, P., Banasek-Richter, C., Bersier, L.-F., Blanchard, J.L., Brey, T., Carpenter, S.R., Cattin Blandenier, M.-F., Cushing, L., Dawah, H.A., Dell, T., Edwards, F., Harper-Smith, S., Jacob, U., Knapp, R.A., Ledger, M.E., Martinez, N.D., Memmott, J., Minternbeck, K., Pinnegar, J.K., Rall, C., Rayner, T., Reuman, D.C., Ruess, L., Ulrich, W., Williams, R.J., Woodward, G. & Cohen J.E. (2006) Consumer-resource body size relationships in natural food webs. Ecology, 87, 2411-2417.

Ledger, M.E. & Hildrew, A.G. (2005) The ecology of acidification and recovery: changes in herbivore-algal food web linkages across a stream pH gradient. Environmental Pollution, 137, 103-108.

Brose, U., Cushing, L., Berlow, E.L., Jonsson, T., Banasek-Richter, C., Bersier, L.-F., Blanchard, J.L., Brey, T., Carpenter, S.R., Cattin Blandenier, M.-F., Cohen, J.E., Dawah, H.A., Dell, T., Edwards, F., Harper-Smith, S., Jacob, U., Knapp, R.A., Ledger, M.E., Memmott, J., Minternbeck, K., Pinnegar, J.K., Rall, C., Rayner, T., Ruess, L., Ulrich, W., Warren, P., Williams, R.J., Woodward, G. and Yodzis, P. & Martinez, N.D. (2005) Empirical consumer-resource body size ratios. Ecology, 86, 2545.

Brown, L.E., Sherlock, C., Milner, A.M., Hannah, D.M. & Ledger, M.E. (2004). The influence of environmental variables on the distribution of diatom communities in an alpine proglacial stream, Taillon-gabietous catchment, French Pyrenees. Pirineos, 158, 73-85.

Ledger, M.E. (2004) A perspective on riverine productivity models. In: Petts G.E. and Kennedy R (eds.) Emerging Concepts for Integrating Human and Environmental Water Needs, US Army Corps of Engineers, Water Operations and Technical Support Programme. Publication: 24632.

Burrell, G.P. & Ledger, M.E. (2003) Growth of a stream-dwelling caddisfly (Olinga feredayi: Conosucidae) on surface and hyporheic food resources. Journal of the North American Benthological Society, 22, 92-104.

Ledger, M.E., Crowe, A.L.M., Woodward, G. & Winterbourn, M.J. (2002) Is the mobility of stream insects related to their diet? Archiv für Hydrobiologie, 154, 41-59.

Ledger, M.E. & Hildrew, A.G. (2001) Growth of an acid-tolerant stonefly on biofilm from streams of contrasting pH. Freshwater Biology, 46, 1457-1471.

Ledger, M.E. & Hildrew, A.G. (2001) Recolonization by the benthos of an acid stream following drought. Archiv für Hydrobiologie, 152, 1-17.

Ledger, M.E. & Hildrew, A.G. (2000) Resource depression by a trophic generalist in an acid stream. Oikos, 90, 271-278.

Ledger, M.E. & Winterbourn, M.J. (2000) Growth of New Zealand stream insect larvae in relation to food type. Archiv für Hydrobiologie, 149, 353-364.

Ledger, M.E. & Hildrew, A.G. (2000) Herbivory in an acid stream. Freshwater Biology, 43, 545-556.

Ledger, M.E. & Hildrew, A.G. (1998) Spatial and temporal variation in the epilithic biofilm of an acid stream. Freshwater Biology, 40, 655-671.

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