Commentary: Environmental RNA and the assessment of organismal function in the field

Environmental RNA (eRNA) is an emerging technique with significant potential for the assessment of organismal function in field settings. It has the advantage of being non-invasive, facilitating insight into the physiological status of an organism without complications associated with processes such as capture, handling, and transportation from the field to the laboratory. It is hypothesised that eRNA approaches will be especially valuable for assessing sublethal stress of species living in environmental settings undergoing change and could therefore be integral for examining population health and for testing hypotheses regarding organismal physiology developed from laboratory studies. However, the successful application of eRNA approaches requires further data regarding the stability and persistence of eRNA in natural substrates; established and validated relationships between molecular biomarkers and the physiological processes they participate in; and an understanding of the contributions of different epithelia in direct contact with the environment (skin, gill, gut) to the eRNA transcriptome. The utility of microRNA as a component of the eRNA pool should be an area of specific future research focus. Ultimately, eRNA has the potential to provide fundamental physiological information regarding the responses of organisms in their natural settings and could increase the sensitivity and acuity of biomonitoring efforts.