Using modelling to establish how radiation affects individuals, populations and ecosystems

Overview

Population models are used by researchers to assess and manage risks to populations, communities and ecosystems in a non-radiological context. Within radiological protection the focus of ecological assessment has been on the protection of populations of flora and fauna, while most research on effects has been at the level of the individual. There is an urgent need to establish the link between the exposure and effects of radiation on individuals and their impact at the level of population, community and ecosystem.

This project will take advantage of the radiation facility we have at Stirling for undertaking experiments to test population modelling predictions to establish how ecological interactions, adaptation and transgenerational effects of radiation combine to cause net changes in ecosystem structure (e.g. population densities, community composition and biodiversity).

Any changes in ecosystem structure will have implications for ecosystem function and services. The traditional method of establishing the risk that ionising radiation poses is through laboratory experiments often using acute, high level exposures. This method is not adequate for environmental situations where chronic, low level exposures occur.

Initially, this project will build a population model for the ladybird beetle (Coleoptera: Coccinellidae) based on information from the literature and preliminary laboratory experiments to determine the effects of ionising radiation; this will be used to predict changes at a population level. The modelling outputs will be tested using mesocosms (controlled mini-ecosystems) housed in a controlled radiation facility. Our radiation facility is designed to be able to undertake long term chronic exposures and is therefore suited to mimic environmental conditions. This will allow the PhD candidate to assess any secondary effects of radiation (e.g. interspecies relationships) that are not routinely considered in radiation experiments. The predator-prey relationship between ladybirds and aphids (Aphidoidea) will be the primary interspecies interaction studied during these experiments.

Following the experimental work, the PhD candidate will be able to refine their population models using the mesocosm findings. We anticipate that this will assess a) what does the stress response to radiation mean for the overall ecosystem if interacting species have different capacities to adapt to radiation? b) Are there tipping points beyond which some populations or communities could go extinct while others thrive; if so, what are any consequences for ecosystem function? c) How are responses at these tipping points affected by species’ capacity to adapt to radiation or to deal with environmental and ecological factors?

Hypotheses derived from laboratory experiments and the modelling work may then be tested through field work within the Chernobyl Exclusion Zone to look at the effects observed across a heterogeneously contaminated environment while also considering the additional impact of non-radiological stressors.

It is expected that this project will feed into the work of other organisations such as the International Commission on Radiological Protection as well as national environmental regulators.

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Image Captions

Images were taken by Dr Raines during fieldwork in the Chernobyl Exclusion Zone.

Methodology

Computer models will be used to test scenarios of how different population densities and species interactions may lead to different population level effects and changes in ecosystem function. This will be explored in collaboration with modelling activities being undertaken within the auspices of the United Nations International Atomic Energy Agency.

Standard guidelines for successful mesocosm experiments will be followed. The mesocosms will be set up for long term continuous exposures in the radiation facility at Stirling. At regular intervals, samples and measurements will be taken and analysed for a range of different parameters to quantify changes in ecosystem structure and processes that underpin ecosystem services whether due to direct or indirect radiation effects.

Project Timeline

Year 1

Conduct a literature review and design an appropriate research strategy for work within the radiation facility and laboratory (mesocosm) studies.

Identify the species to be used within the modelling and mesocosms.

Undergo further training in data analysis, modelmaker, MATLAB and population modelling.

Create, test and improve population models paying specific attention to the possible complications of multiple stressors and inter-species relationships.

Attend and present at one local conference (probably that of the Co-ordinating Group on Environmental Radioactivity within the UK).

Participate in International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Year 2

Establish and maintain the mesocosms.

Expose the mesocosms to different doses of radiation in our radiation facility and examine for any changes that occur.

Attend and present at one local conference (probably that of the Co-ordinating Group on Environmental Radioactivity within the UK).

Continue to participate in International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Year 3

Refine the population models and develop predictions for testing within the Chernobyl Exclusion Zone

Participate in fieldwork to test the model predictions within the Chernobyl Exclusion Zone.

Continue to participate in International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Attend and present at one local and one overseas conference (e.g. ICRER – the international Conference on Radioecology and Environmental Radioactivity.

Year 3.5

Thesis finalisation and paper writing (although it is anticipated that these activities will be ongoing throughout the PhD).

Training
& Skills

The analytical and mathematical techniques required for this study are already established at the University of Stirling and CEH and include the use of radiation experiments in the controlled facility, conventional assessment of radiation effects, data analysis and computer modelling. The successful applicant will also undergo specific training in population modelling with Prof Jordi Vives at SCK-CEN in Belgium.

The successful applicant will receive training in experimental design, data analysis, and radiological protection related to the project work. They will attend classes on Effective Research, Scientific Writing, Statistics for Environmental Evaluation (and use of R), Presentation Skills, and Radiological Environmental Protection.

The student will also benefit from wider interaction within research groups at Stirling and CEH Lancaster. We will establish regular meetings via Skype between CEH and Stirling to allow discussions on the student’s work. They will be expected to present the results of their research annually at the BES student symposium and to attend the annual UK COGER meetings which have an emphasis on encouraging students to present their work. The student will also be expected to present their work at one international conference. The student will have the opportunity to interact with wider student networks (and training opportunities) though the European Radioecology ALLIANCE.

References & further reading

Alonzo, F., Hertel-Aas, T., Real, A., Lance, E., Garcia-Sanchez, L., Broadshaw, C., Batlle, J. V., Oughton, D. H. and Garnier-Laplace, J. (2016) Population modelling to compare chronic external radiotoxicity between individual and population endpoints in four taxonomic groups. Journal of Environmental Radioactivity, 152, pp. 46-59.

Beresford, N.A., Copplestone, D. (2011) Effects of Ionizing Radiation on Wildlife: What Knowledge Have We Gained Between the Chernobyl and Fukushima Accidents? Integer. Environ. Ass. Manag., 7, 371-373.

Bradshaw, C., Kapustka, L., Barnthouse, L., Brown, J., Ciffroy, P., Forbes, V., Geras’kin, S., Kautsky, U. and Brechignax, F. (2014) Using an Ecosystem Approach to compliment protection schemes based on organism-level endpoints. Journal of Environmental Radioactivity, 136, pp. 98-104.

Copplestone, D., Beresford, N.A., Howard, B.J. (2010) Protection of the Environment from Ionising Radiation: developing criteria and evaluating approaches for use in regulation. J. Radiol. Prot., 30, 191-194.

Møller & Mousseau (2006) Biological consequences of Chernobyl: 20 years on. Trends Ecol Evol. 21:200-207.

Vives i Batlle J., Sazykina T., Kryshev A., Wood M., Smith K., Copplestone D. and Biermans G. (in press) Modelling the effects of ionising radiation to a population of field voles (Microtus agrestis) from the Chernobyl Red forest in an ecological context. Ecological Modelling.

Further Information

Further information can be obtained from:
David Copplestone +44 (0)1786 467852, Email: david.copplestone@stir.ac.uk
Nick Beresford +44 (0)1524 595856, Email: nab@ceh.ac.uk

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