Carole Lee

Department: Biosciences
Discipline: Biosciences
Research Centre/Unit: Environmental Biology

Project Summary

Research topic

My current research investigates the effects of the social and physical environment on welfare of laboratory zebrafish. I am investigating measures of behaviour and levels of activity that indicate wellbeing in zebrafish; the effects of tank size, shape, and stocking density on aggression and affiliative behaviour; how husbandry practices affect stress in zebrafish; and whether simple changes in the tank or social environment (e.g. tank/water changes) can provide positive stimulation for laboratory fish. I am also developing a computer model for welfare assessment of zebrafish. The model will use weighted factors of attributes such as housing conditions, physiology, health, etc., based on collated scientific data, to assess the welfare status of the animals and produce a welfare score as output. My work to date suggests that significant welfare benefits may be achieved through simple and practicably changes to current practise in the housing and maintenance of zebrafish in research laboratories.

Why this is important

Understanding the effects of environmental surroundings on zebrafish will not only provide an important opportunity to develop methods on how to recognise and measure wellbeing in laboratory fish but can also be used to encourage practise to improve housing and husbandry techniques and promote best practice amongst facility managers. Improved welfare will mean that zebrafish function more optimally, with likely improved reliability of research data and furthermore help drive reduction in the number of fish required for each experiment as well as reducing the likelihood of needing to repeat experiments. This research contributes directly to the principles of the 3Rs (Replacement, Reduction and Refinement) by reducing the number of experimental fish required and in parallel refining animal welfare.

Practical implications

Data from this project will be used to provide recommendations to the scientific community on how best to maintain laboratory zebrafish with a focus on mitigating against stress, optimising life history traits (such as growth and fecundity) and improving scientific validity. Findings from this study using zebrafish are likely to have application for other fish species in laboratories and public aquaria, and to species economically important to aquaculture and the aquarium trade. The work will also contribute to understanding of why captive-reared fish typically have lower fitness in natural environments than wild conspecifics. The study may help also identify modifications of the captive rearing environment that can improve the performance of hatchery fish.

Previous research

The effects of environmental enrichment and environmental stability on the welfare of laboratory zebrafish

I found that environmental enrichment, in the form of gravel and plants, affected survivorship, growth, body condition and behaviour in laboratory-maintained zebrafish. Larvae in enriched tanks had higher survivorship than larvae in plain tanks. Fish reared in enriched tanks were shorter than fish reared in plain tanks at 60 days post-fertilisation. Females in enriched tanks had higher body condition than females in plain tanks and body condition was more variable in males in plain tanks than in enriched tanks. Fish from enriched tanks also displayed lower levels of anxiety than fish from plain tanks when placed in a novel environment, and resource monopolisation was higher for enriched fish than for plain fish. Data generated by this study enhanced understanding of what environmental conditions improve housing for laboratory zebrafish.

Effects of environmental complexity on the behaviour of laboratory-maintained zebrafish

This project asked whether zebrafish raised in different environments differ in behaviour and whether the behavioural phenotypes of zebrafish are fixed. To address these questions, shoals of zebrafish were raised in ‘plain’ and ‘enriched’ environments and activity and aggression compared. Shoals were then transferred from plain to enriched environments and vice versa, and activity and aggression compared with levels before the transfer. No differences in activity were found between fish reared in plain tanks and those reared in enriched tanks and activity levels did not change when the environment changed. Changing the environment did, however, increase aggressiveness in fish moved from enriched tanks to plain ones. These results suggest that the behaviour of zebrafish is not affected by the environment in which they are raised and that behavioural phenotypes are not fixed.

Supervisory Team

Primary Supervisor: Prof. Charles Tyler

Secondary Supervisor: Dr. Gregory Paull

Wider Research Interests

  • Behavioural plasticity and individual differences in cognition and behaviour among fish
  • Evolutionary history and environmental context of fish behaviour
  • Fish perception, learning and memory

Authored Publications/Reports

Lee, C. J., Paull, G. C., & Tyler, C. R. (2019) Effects of environmental enrichment on survivorship, growth, sex ratio and behaviour in laboratory maintained zebrafish Danio rerio, Journal of Fish Biology , 94, 86–95

Lee, C.J., Tyler, C.R., Paull, G.C. (2018) Can simple tank changes benefit the welfare of laboratory zebrafish Danio Rerio?, Journal of Fish Biology, 92, 653–659

Lee, C. J., Tyler, C. R., & Paull, G. C. (2020) Behavior of wild populations, In Cartner, S. et al. (eds) The Zebrafish in Biomedical Research

Lee, C. J., Tyler, C. R., & Paull, G. C. (2020) Geographic range and natural distribution, In Cartner, S. et al. (eds) The Zebrafish in Biomedical Research