Meaningful and objective inference in radioecological field studies

Anthropogenic releases of radiation are of on-going importance for environmental protection, but the radiation doses at which natural systems begin to show effects are controversial. More certainty is required in this area to achieve optimal regulation for radioactive substances. We recently undertook a large fieldstudy (278 sampled animals and 20 sites) of the association between environmental radiation exposures and small mammal gut-associated microbiomes (fungal and bacterial) in the Chornobyl Exclusion Zone. Using individual measurements of total absorbed dose rates and a study design and analyses that accounted for spatial non-independence we found no, or only limited, association. Our findings contradicted those of other studies on the effects of radiation on small mammal microbiomes. The authors of those other studies challenged our findings, including criticising our study design. In reflecting on and responding to these criticisms, it became apparent that there are significant misunderstandings of the true nature of independent replication in field studies. Recognising the importance of spatial non-independence is essential in the design and analysis of radioecological field studies, but this has seemingly been overlooked in a numerous publications reporting associations between radiation and biological effects in wildlife under field conditions. In this presentation we explore some of the pitfalls in methodological design of radioecological field studies and approaches to avoiding falling foul of these pitfalls.