Skip to content
Skip to navigation menu


Prof Steve Ormerod  -  MSc, PhD, FIEEM

I came to Cardiff in 1980 for the prestigious UWIST MSc in Applied Hydrobiology, from there completing a PhD on water quality and invertebrates in the Wye river-system. Simultaneously, I developed an interest in the ecology of river birds, showing for the first time how this group was affected by acid rain. These major themes — freshwaters, invertebrates and birds in aquatic habitats — have continued to provide my major research models.

From 1984, I led a post-doctoral group investigating the ecological effects of acidification in upland rivers using surveys, models and ecosystem-scale experiments at the Llyn Brianne Stream Observatory. These experiments have now run for over 30 years, and my catchment-scale work has expanded to encompass global change effects on freshwaters ecosystems on three continents.  Most recent work with colleagues such as Dr Isabelle Durance, Dr Ian Vaughan, Stefano Larsen and Christy Morrissey has provided some of the world’s first evidence about the sensitivity of headwaters to climate change while also telling the remarkable story of how the recovery of British rivers from gross sanitary problems has been tempered by the growing challenge of diffuse pollution.

Research income now approaches £6 million, and over 260 scientific papers have been cited around 8500 times at H > 47 (Google Scholar).

1.    Global change effects on freshwater organisms and ecosystems

Over the last 30+ years, prominent themes in my work have been large-scale, long term impacts of global change on freshwater ecosystems as well as ecosystem recovery where such stressors have been managed or removed.

Examples include:

  • Impacts and management of acid rain effects on stream organisms and ecosystem processes (eg Ormerod & Durance 2009; Pye et al. 2012 )
  • Climate change effects on invertebrate composition, extinction processes and population dynamics in upland rivers (Durance & Ormerod 2007, 2010; Clews et al. 2010)
  • Adaptive strategies to manage climate-change effects (Ormerod 2009; Durance & Ormerod 2009)
  • Consequences of changing land use patterns for stream ecosystems in Britain and overseas (Manel et al. 2000; Larsen et al. 2010)
  • Contrasting multiple stressor effects on streams and rivers (Ormerod et al. 2010; Gutiérrez-Cánovas et al. 2013)
  • Freshwater biodiversity conservation in the face of global change (Ormerod et al. 2010; Larsen & Ormerod 2010; 2014)
  • National trends in British rivers in response to urban wastewater and diffuse pollution (Vaughan & Ormerod 2012)

(Abstracts and many full texts of all my papers can be found at

Llyn Brianne Stream Observatory


The unique Llyn Brianne Stream Observatory, operational from 1981, has multiple experimental and reference streams that have figured prominently in understanding global change effects on freshwater ecosystems. 

2.    River ecosystem services 

River ecosystem services have become an increasingly important focus in my work, in particular to understand how biodiversity supports services and how environmental stressors erode ecosystem functions and service delivery.

Examples include

  • Co leadership of the freshwater sections of the National Ecosystem Assessment for Defra and the Devolved Administrations  (Maltby & Ormerod 2011 )
  • Acting as Cardiff PI in the £3.1 million NERC BESS project, Duress (Diversity in Upland Rivers for Ecosystem Service Sustainability; from 2012)
  • Acting as Cardiff PI and co-leader of catchment studies in the €9 million EU-funded MARS project (Managing Aquatic ecosystems and water Resources under multiple Stress; from 2014)
Photo of Prof Steve Ormerod

The UK NEA assembled key data on the status and trends in ecosystem services delivered by British fresh waters.

3.    The ecology of river and wetland birds

I became interested in the ecology of river-birds, and in particular dippers, while researching aquatic invertebrates for my PhD.  This interest led to some of the world’s first evidence that birds could be affected by acid rain (eg Ormerod et al. 1991), and in turn some of the world’s best known autecological bird research.  The concept of using dippers as indicators of acidity led also to research into their role as indicators of broader aspects of water quality that still continues.  With Dr Christy Morrissey in the University of Saskatchewan, recent examples include:

  • Assessments using dipper eggs of the biotransport of contaminants into rivers of the Pacific North West of Canada by migrating salmon (Morrissey et al. 2012)
  • Revealing spatial pattern in contaminant distribution from the local to inter-continental (Ormerod et al. 2000; Morrissey et al. 2010)
  • Illustrating how some novel pollutants, such as PBDE flame retardants, reach some of the highest levels ever recorded in birds in British urban rivers (Morrissey et al. 2013)
Photo of dipper

Dippers have recolonised the formerly polluted rivers in South Wales but remain scarce on unproductive, acidified streams (Image by Nigel Blake)

Photo of grey wagtail

Grey wagtails are less affected by river pollution than dippers but still most abundant as breeding birds on productive, tree-lined, insect-rich stream and rivers (Image by Nigel Blake)


Current and recent sponsors include:

Natural Environment Research Council (including the £3.1 million Duress Project)
European Union (where we co-lead catchment-scale in the €9 million MARS project)
Esmée Fairbairn Foundation (who currently fund the Llyn Brianne Stream Observatory)
Natural Resources Wales
Knowledge Exchange Studentship Scheme
Leverhulme Trust
Daphne Jackson Trust
The Royal Society
Wessex Water
Countryside Council for Wales
Swiss Foundation for Scientific Research
The Welsh Government
The Environment Agency
Freshwater Biological Association
Royal Geographical Society
National Geographic Society (USA)
National Museum of Wales
Wye and Usk Foundation
Scottish Environmental Protection Agency
Cardiff City Council
Forestry Commission
SMEs (Shawater Ltd, Ambient Hydro, APEM Ltd, ENSIS Ltd, Cascade Consulting)

Current and recent PhD students

Rhodri Thomas (President’s Studentship with Ian Vaughan and Jose Constantine)  Predicting river habitat response to climate change

Norhisham Ahmad Razi (Joint with Mark Jervis) Insect life-history response to global change

Rhian Newman (Joint with Sian Griffiths and Bill Riley CEFAS)  Artificial light and predator-prey dynamics in freshwaters

Marian Pye (Joint with Isabelle Durance and Ian Vaughan) Catchment and riparian subsidy effects on upland stream ecosystems

Sarah Lee (Joint with Rupert Perkins) Climate change and the ecology of Cardiff Bay

Hannah Burton (President’s Studentship joint with Mike Bruford and Hefin Jones)

Caitlin Pearson (BBSRC studentship with Ian Vaughan and Bill Symondson) Agricultural effects on upland rivers

Matt Dray (Presidents Studentship joint with Hefin Jones, Sue Hartley (York) and Rupert Perkins) Effect of elevated CO2 on tree litter chemistry and decomposition

Kate Walker-Springett (ESRC/NERC Studentship joint with Jose Constantine and Lorraine Whitmarsh) Public perception of habitat management for pearl mussel in response to climate change

Paul Sinnadurai (Jointly supervised with Dr Hefin Jones) Dispersal and distribution in riparian Coleoptera

Stephen Thomas (KESS Studentship joint with Sian Griffiths) Riparian management effects on macroinvertebates and salmonids in upland streams affected by climate change

Successfully completed students

Dr Alisa Watson (NERC CASE studentship with WWT) The ecology of scarce wetland molluscs

Dr Beth Lewis (Wye and Usk Foundation; co-supervised with Dr Brian Reynbolds, CEH Bangor) The effects of liming on invertebrate recovery from acidification

Dr Clare Bale (NERC; jointly supervised with Dr Sian Griffiths) Behavioural avoidance and sheltering behaviour of salmonids during acid episodes

Dr Dave Bradley (PhD studentship funded by Defra) Dynamic processes in acid senstitive streams

Dr Emma Durward (Cardiff University/Llysdinam Trust; co-supervised with Dr Fred Slater)

Dr Esther Clews (Wye and Usk Foundation) The effects of hydrochemical restoration on river organisms

Dr Fabio Lepori (PhD studentship funded by the Swiss Foundation for Scientific Research) The ecological effects of acid episodes in the Swiss Italian Alps

Dr Faye Merrix (Cardiff City Council; Jointly supervised by Dr Steve Thackaeray, CEH Lancaster) Zooplankton ecology in Cardiff Bay

Dr H. Ceri Williams (NERC studentship; co-supervised with Prof Mike Bruford) Dispersal and genetic variation in Baetis mayflies

Dr Heike Hirst Ecological influences on diatom responses to water quality

Dr Hem Sagar Bharal (Joint with the University of Amsterdam) Community structure and habitat associations of lowland grassland birds of Nepal.

Dr Ian Vaughan (PhD Studentship funded by the Environment Agency) Modelling the distribution of river birds using habitat data

Dr Jacqui Barnes (NERC; joint supervision with Dr Ian Vaughan) Habitat complexity and river biodiversity

Dr Laura Trodden (Cardiff School of Engineering; jointly supervised with Dr Catherine Wilson) Climate change, stream hydraulics and stream invertebrates

Dr Liz Chadwick (Cardiff University/Llysdinam Trust; co-supervised with Dr Fred Slater) The influence of climatic variation on the ecology of common toads

Dr Muriel Alix (Cardiff City Council) The ecology of invasive zebra mussels in Cardiff Bay

Dr Renata Kowalik (PhD studentship funded by Defra) Detecting and modelling the effects of acid episodes on stream fauna

Dr Richard Jenkins The ecology of Water Rail Rallus aquaticus

Dr Seb Buckton The ecology of Himalayan River Birds

Dr Stefano Larsen (Wye and Usk Foundation) Effects of sediment deposition on upland stream organisms

Dr Zoe Masters (FBA/Cardiff University Ray Beverton Memorial Studentship) The effects of geographical isolation on stream recovery from acidification