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Dr Siân Griffiths

Dr Siân Griffiths

Senior Lecturer

School of Biosciences

+44 (0)29 2087 6422
+44 (0)29 2087 4116
Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX
Welsh speaking


Research overview

My research focuses on the following themes in aquatic ecology, which link fundamental research to practical problems faced by conservation biologists and managers. The work uses a range of behavioural and ecological tools and investigates the interactions between individual behaviour and population processes essential for understanding and conserving natural biodiversity.

  1. Behavioural ecology and the evolution of fish schooling
  2. Consequences of climate change for fish behaviour and river ecology
  3. Ecosystem quality and the distribution of fish in rivers

Each theme is expanded under 'Research' above and collaborative work with various agencies is highlighted.


I studied for my first degree at the University of Wales, Aberystwyth between 1990 and 1993, and for my MSc at the University of Oxford in 1994. I completed my PhD on the schooling behaviour of freshwater fish at the University of St. Andrews in 1997 where I was supervised by Professor Anne Magurran ( During this time my field work was based in Trinidad and Tobago, and at the CEH River Laboratory, Dorset ( )

In 1998 I began working as a NERC Research Fellow based at the University of Glasgow ( and the Fisheries Research Services, Freshwater Laboratory, Pitlochry ( I joined Cardiff University in 2000 when I was awarded an extension to my NERC fellowship and was simultaneously appointed as lecturer in animal ecology. In 2007 I was appointed Senior Lecturer.




















Behavioural ecology and the evolution of fish schooling

This research theme addresses a question of key importance in animal behaviour and evolution of social living: how animals decide which group to join. I am investigating this topic in collaboration with Prof. A. Magurran (St Andrews University), Dr John Armstrong (Marine Scotland Science, Freshwater Laboratory, Pitlochry), Dr Alfredo Ojanguren and Dr James Orpwood using the European minnow to test individual recognition abilities and the benefits of association between familiar groups of fish. Social behaviour of fish is also being tested using sharks in the Bahamas, with Dr Tristan Guttridge (Bimini Biological Field Station). This work links important behavioural parameters with ecology and conservation of wild fish.

Consequences of climate change for salmonid ecology

Climate change has major effects on the distribution patterns and community composition of stream organisms and we are testing how habitat enhancement in S. Wales rivers, for example, the maintenance and restoration of broadleaf trees in the riparian zone, increases Atlantic salmon resilience to climate change. This work is a collaboration that is strongly linked with the research interests of Prof. Steve Ormerod, another member of the OnE (Organisms and Environment Research Division) and Dr. Isabelle Durance (Sustainable Places Research Institute), as well external collaborators (The NRW, South East Wales Rivers Trust and the Game and Wildlife Conservation Trust).

Other UK work is adopting a behavioural approach, examining Atlantic salmon time budgets, space use (including sheltering behaviour) and growth, in the wild and in indoor streams, to investigate the mitigating effects of riparian shading on salmon ecology (with Dr John Armstrong, Marine Scotland Science and Dr James Orpwood, The Scottish Fisheries Co-ordination Centre, SFCC). The sheltering behaviour of fish is an ongoing interest. Many fish, including Atlantic salmon, are nocturnal at cold temperatures (sheltering in interstitial habitats during daylight and emerging to forage at night). Factors that influence sheltering, including water temperature, light conditions (e.g. artificial street lighting) and competition from invasive species have important predicted effects on survival through food intake, growth and predator avoidance. Research on the effect of artificial street lights on aquatic ecology is being conducted in collaboration with Dr Bill Riley and Prof. Gordon Copp at CEFAS (Centre for Environment, Fisheries & Aquaculture Science), Lowestoft.

Ecosystem quality and the distribution of fish in rivers

The services provided by stream and rivers, including provision of economically and culturally valuable fish, may be compromised by future climate change effects on water availability and temperature, in conjunction with other anthropogenic pressures such as water abstraction. Work conducted as part of the DURESS (Diversity in Upland Rivers for Ecosystem Service Sustainability) consortium is testing the hypothesis that biodiversity is central to the sustainable delivery of upland river ecosystem services under changing land-use and climate ( Other work, in collaboration with Dr Isabelle Durance (Sustainable Places Research Institute) and Dr Hefin Jones (OnE), is investigating the mechanisms that sustain fish populations in varying flow regimes.


Current and recent sponsors of work include:

  • Afonydd Cymru
  • Centre for Environment, Fisheries & Aquaculture Science
  • Christine Baltzer Parks Environmental Foundation
  • Coleg Cymraeg Cenedlaethol
  • Ecoexplore
  • Game and Wildlife Conservation Trust
  • Knowledge Economy Skills Scholarships
  • Marie Curie Individual Fellowship from the European Commission
  • Natural Environment Research Council
  • Natural Resources Wales
  • South East Wales Rivers Trust

Current members of research group

Dr Tristan Guttridge

  • Population dynamics of sharks in the Bahamas.
  • Funded by Christine Baltzer Parks Environmental Foundation

Ifan Jâms

  • Supervisors: Drs Siân Griffiths, Isabelle Durance & Hefin Jones
  • Teitl doethuriaeth: Effaith argaeledd dŵr lleihaol ar eog a brithyll afonydd Cymru
  • PhD project title: The influence of drought on trout and salmon in Welsh rivers
  • Funding: Coleg Cenedlaethol Cymraeg

Rhian Newman

  • Supervisors: Drs Siân Griffiths, Professor Steve Ormerod, Dr Rob Thomas and Dr Bill Riley
  • Project title: Artificial night light as a barrier to migration and movement of high value fish and fisheries
  • Funding: KESS, Ecoexplore & CEFAS

Stephen Thomas

  • Supervisors: Professor Steve Ormerod & Dr Siân Griffiths
  • PhD project title: Adapting Rivers to Climate Change to Support High Value Fish and Fisheries. Funded by KESS, South East Wales Rivers Trust & Environment Agency
  • Funding: KESS & South East Wales Rivers Trust

Janine Burnham

  • Supervisors: Drs Siân Griffiths, Isabelle Durance & Dylan Roberts
  • MRes project title: Testing the effect of riparian habitat rehabilitation in mitigating climate change impacts on native UK fish
  • Funding: KESS & Game and Wildlife Conservation Trust

Rhidian Thomas

  • Supervisors: Dr Siân Griffiths, Dr Jo Cable, Dr Bill Riley & Prof Gordon Copp
  • MRes project title: The impact of artificial night lighting on the interaction between native fish and invasive species
  • Funding: KESS, Ecoexplore & CEFAS

Former group members


Dr Steven Kessel
  • Population dynamics of the lemon sharks in the Bahamas (Negaprion brevirostris).
  • Funded by Christine Baltzer Parks Environmental Foundation
Dr Michele Drès
  • Molecular analysis of kin-biased spatial clustering of juvenile Atlantic salmon Funded by the Cardiff Young Researcher Initiative
Dr Johan Höjesjö
  • Habitat adaptations in salmonids, effects of intra- and inter-specific competition Funded by a Marie Curie Individual Fellowship
Dr Alfredo Ojanguren
  • The behavioural and ecological consequences of shoaling decisions in fish Funded by the NERC (Natural Environment Research Council)
Dr James Orpwood
  • The behavioural and ecological consequences of shoaling decisions in fish Funded by the NERC (Natural Environment Research Council)

Postgraduate students

Dr Bart Adriaenssens
  • Coping with divided attention: effects of the social and physical environment on the performance of fishes. In collaboration with Gothenburg University, Sweden.
Dr Demetra Andreou
  • Prevalence, impact and life cycle of an emerging endemic disease: the Rosette-like agent. Funded by CEH.
Dr Claire Bale
  • The Influence of Acid Episodes on the Behavioural Ecology of Freshwater Fish. Funded by the NERC
Dr Dean Burnard
  • The impact of the sex pheromones of alien fish species on the reproductive behaviour of native fish. Funded by the NERC
Laura Evans
  • Bullheads as keystone species for river ecosystem services. Funded by KESS and Afonydd Cymru.
Dr Wendy Fernandes
  • Interactions between family traits, environment survival and migration strategies in Atlantic salmon. Funded by Wessex Water, CEH, CEFAS
Dr Andrew Harwood
  • Competition among juvenile Atlantic salmon and Brown trout. Funded by the NERC.
Becky Marsh
  • The effect of temperature on refuge use in juvenile Atlantic salmon. Funded by LEA
Dr James Orpwood
  • Refuge use among stream-dwelling Atlantic salmon. Funded by Cardiff University
Phoebe Harris
  • The effect of artificial night light on river ecology. Cardiff University 125 scholarship.
Dr Lois Richards-Hobbs
  • Dietary conservatism in fish: its evolutionary consequences in social and solitary animals. Funded by the Waltham Foundation
Dr Keith Williams
  • The ecology of Atlantic salmon in relation to upland lochs. Funded by The Conon and Alness District Fisheries Board and Cardiff University


Aside from collaborations within the school (with Prof. Mike Bruford on molecular studies of declining salmon populations, Dr Jo Cable on parasite transmission among shoaling fish and Prof. Steve Ormerod, Dr Isabelle Durance and Dr Hefin Jones on the effects of climate change on upland fish ecology) the following are external collaborators on funded projects.

Dr John Armstrong

  • Marine Scotland Science, Freshwater Laboratory, Pitlochry
  • Behaviour and Ecology of juvenile Atlantic salmon

Prof Gordon Copp

  • Lowestoft Laboratory, CEFAS
  • Invasive species ecology

Dr Johan Hojesjo

  • University of Gothenburg, Sweden
  • Habitat adaptations in salmonids, effects of intra- and inter-specific competition

Frank Jones

  • Afonydd Cymru
  • The role of bullhead in river ecosystems

Professor Anne Magurran

  • University of St Andrews
  • Evolution of shoaling behaviour in European minnows

Professor Manfred Milinski

  • Max Planck Institute of Limnology, Germany
  • Mate choice decisions of female sticklebacks

Dr Alex Pollard

  • Eco-explore
  • The effects of artificial night light on river ecology

Dr Bill Riley

  • Lowestoft Laboratory, CEFAS
  • Ecology of juvenile salmon

Dylan Roberts

  • Game and Wildlife Conservation Trust
  • Ecological effects of riparian management