I 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. My Ph.D. research at QMW (completed 1997) investigated the relationship between acidification-induced biodiversity loss and ecosystem processes (herbivory) in upland streams. I 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 I worked on growth and trophic ecology of NZ stream invertebrates. Thereafter, I held a NERC-Freshwater Biological Association Pioneer Research Fellowship, based here at the School of Geography, Earth and Environmental Sciences in Birmingham (with Dr Sandy Milner, 1999-2003). I was appointed to a Lectureship within the School from 2003.

Research Students since 2001

Current

Alex Poynter (2009-) ‘Impacts of environmental stressors on the River Itchen Ranunculus community’ (funded by the Environment Agency), co-supervisor with Dr L. Batty, Dr. J. Bridgeman (UoB) and S. Medgett (EA).

Ian Thornhill (2008-) ‘Water quality and biodiversity of urban ponds’ (funded by NERC with CASE support from the Macaulay Institute), co-supervisors Prof A. Baker and Dr L. Batty (U of B) and Dr N. Friberg (Macaulay Institute).

Completed

Katie Aspray (2008-) ‘Freshwater biodiversity and ecosystem function in changing moorland landscapes’ (funded by NERC OPEN CASE studentship with CASE support from Natural England), co-supervisor, with Dr L.E. Brown (lead), Dr J. Holden (University of Leeds), Dr C.P. Mainstone (Natural England).

Jessica Frame PhD (2010, University of Birmingham) ‘Biological barriers to the restoration of freshwater ecosystems’ (funded by GEES with support from the Centre for Ecology and Hydrology), co-supervisors Dr J.I. Jones (CEH Dorset), Prof S.J. Ormerod (Cardiff University) and Dr J.P. Sadler (U of B).

Helen Vincent PhD (2010, University of Birmingham) ‘Algae-herbivore interactions in stream food webs’ (funded by NERC with CASE support from the Centre for Ecology and Hydrology), co-supervisors Dr A.M. Milner (U of B) and Dr J. Murphy (CEH Dorset).

Rebecca Harris PhD (2006, University of Birmingham) ‘The effect of experimental drought disturbance on macroinvertebrate assemblages in stream mesocosms’ (funded by NERC-Freshwater Biological Association), with Dr A.M. Milner

Research Cluster / Group Affiliation

Water Sciences

Hydroecology

Research Interests

• Freshwater community ecology
• Aquatic biodiversity
• Food webs
• Community structure and function
• Trophic ecology
• Spatial patchiness
• Benthic invertebrates
• Algae   

Current / recent research

My research in freshwater systems encompasses community ecology, biodiversity and environmental change. My research group work at a range of spatial and temporal scales, utilizing laboratory microcosms, field mesocosms, and natural environmental gradients in real ecosystems. Current research has four overlapping foci: disturbance ecology, food webs, species interactions, particularly plant-herbivore dynamics, and stressor effects on biodiversity and ecosystem function. Ongoing projects are detailed below. Some of these represent collaborations with a range of specialists in the UK and overseas. 

Disturbance, biological legacies and community development

Recent work with Rebecca Harris (PhD student), Sandy Milner and Patrick Armitage used mesocosm experiments to examine the interplay between abiotic disturbances (e.g. floods and droughts) and the biotic processes that affect spatial heterogeneity in aquatic ecosystems. NERC and FBA funded. 

 

Disturbance and dynamic stability

Predictions that climate change could alter the flow regimes of rivers and streams have stimulated experiments that examine the effect of increased drought disturbance on population dynamics and biodiversity in freshwater systems. Collaborators include Rebecca Harris (PhD student), Patrick Armitage (CEH) and Sandy Milner. NERC/ FBA funded.

 

Environmental change and freshwater food webs

Environmental perturbations can cause non-random species loss in ecological communities, altering the architecture and functioning of food webs. I am investigating the impact of drought on secondary production and energy flow through benthic food webs in collaboration with Guy Woodward (QMUL), Francois Edwards (QMUL & CEH), Lee Brown (Leeds) and Sandy Milner. NERC funded.

 

Model food webs: replicability and realism

Mesocosms are enclosed experimental units used as research tools in many ecosystems. Current research evaluates the extent to which artificial streams are replicable and mimic conditions in the natural environment. NERC funded.

Collaborators: Guy Woodward (QMUL), Francois Edwards (QMUL & CEH), Lee Brown (Leeds) and Sandy Milner.

 

Interaction strengths within the algae-herbivore sub-web

Food web models require realistic estimates of interaction strength between consumer and resource populations. Research with Helen Vincent (PhD student), John Murphy (CEH) and Sandy Milner (Birmingham) is examining the distribution and context dependency of interactions between algae and invertebrate herbivores in lowland stream food webs. NERC and CEH funded.

 

Environmental change, aquatic biodiversity and species interactions

Biological barriers to the restoration of biodiversity in freshwaters

Current research with Jessica Frame (Ph.D. student), Steve Ormerod (Cardiff), Iwan Jones (CEH Dorset) and John Sadler (Birmingham), is examining whether biological recovery from acidification is limited by biotic interactions in upland streams. GEES and CEH funded.

 

 

 

Impact of stressors on species interactions

Surface-water acidification damages upland freshwaters ecosystems, producing a natural experiment in which to observe the effect of biodiversity loss on processes in real ecosystems. My Ph.D. research, with A.G. Hildrew (QMUL London), examined plant-herbivore interactions in streams of contrasting pH. We demonstrated that biodiversity loss within the primary consumers was non-random, being concentrated within the specialist herbivore guild, and that a remnant generalist fauna partially compensated for the loss, grazing algae in the absence of specialists. NERC funded. 

Administrative Responsibilities

Admissions Tutor, Environmental Science/Environmental Management.

Key Publications since 2001

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. (in press). Mesocosm experiments in ecological climate change research. Advances in Ecological Research.

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

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., 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.