The main aim of UMB4a is to evaluate the consequences of ionizing radiation and radioactive contamination on non-human biota on a higher level of organization, i.e. "How do effects of radiation manifest themselves at the community/ecosystem level?" Our current knowledge of radioecological effects is mainly based on assessments of effects on single species in the laboratory or in the field. The key challenge is to translate this knowledge to cover ecosystems of multiple species together with the abiotic part of the environment.
Our overarching hypothesis has been that ecosystem processes (e.g. food chain interactions, competition between and within species, changes in biodiversity) can result in indirect effects from exposure to ionizing radiation. Under UMB4a, we have used experimental micro- and mesocosms to explore such effects. Micro- and mesocosms in biological studies are artificially created ecosystems used to predict the behaviour of natural ecosystems. For example, a microcosm can be a small aquatic system in an aquarium-like tank, or a terrestrial system in a greenhouse. Some larger mesocosms have been placed in netted-off areas in ponds, lakes or even oceans. Larger ecosystems have also been created to replicate an environment and study global scientific issues like climate change.
Figure: Conceptual model of the microcosm exposed to gamma, illustrating each species and component of the aquatic ecosystem and the interactions between them. Solid lines = trophic transfer and dotted line = excretion/decay.
We have published a literature review (Haanes et al. 2019) of microcosms suitable for use in radioecological studies. In radioecological studies size and location limitations are important as large volumes involve problems with waste and exposure to gamma fields. The review included recommendations for how microcosms can be optimized for studying the effect of ionizing radiation on ecosystems.
In addition, we have published a study on ionizing radiation effects in a small aquatic ecosystem (Hevrøy et al. 2019), where we exposed microcosms to gamma radiation in a climate chamber, and a mesocosm study that investigated the uptake of radionuclides in a benthic food web from the Baltic sea (Holmerin et al, submitted).
Sampling from microcosms exposed to gamma radiation in climate chamber at Figaro Facility at NMBU. Dr. Clare Bradshaw (left) and PhD student Anna-Lea Golz (right), both from Stockholm University.
Key publications
Holmerin, I., Jensen, L.K., Hevrøy, T.H. and Bradshaw, c. (submitted, 2020). Trophic Transfer of Radioactive Micronutrients in a Shallow Benthic Food Web. Environmental Toxicity and Chemistry
Haanes, H., Hansen, E.L., Hevrøy, T.H., Jensen, L.K., Gjelsvik, R., Jaworska, A. and Bradshaw, C. (2019). Realism and usefulness of multispecies experiment designs with regard to application in radioecology: A review. Science of the Total Environment, Vol.718.
Hevrøy, T. H., Golz, A-L., Hansen, E. L., Xie, L., Bradshaw, C. (2019). Radiation effects and ecological processes in a freshwater microcosm. Journal of Environmental Radioactivity 203: 71-83.
