Our new review article on environmental DNA (eDNA) and marine environmental impact assessment (EIA) is in the Journal of Marine Science and Engineering (JMSE) this month. Environmental DNA offers numerous possibilities for increasing the efficiency of tasks that concern biodiversity in EIA, such as monitoring changes in community composition. The article reviews the advantages, disadvantages and new opportunities suggested by this approach within marine EIA.
We are delighted that our article was also selected for the cover of the current issue of JMSE!
For marine EIA, what would be desirable is a capacity to assess impact(s) from a change in the receptor species eDNA signal using water column measurements. At present, achieving this would require more mathematical and statistical development, as well as better understanding of shedding rate dynamics and the fate of DNA molecules. In addition, more comparative eDNA studies among the scientific community are needed, including initiatives such as assay validation programs (e.g. https://edna-validation.com/) which are part of ensuring high data quality.
This article fits within the continuity of our work on systems-based and quantitative environmental impact assessments (Coston-Guarini et al. 2017). One of the issues we have encountered repeatedly has been that considering impact on an ecological system through the concept of a receptor species is often too restrictive, if the overall goal of EIA is to conserve ecosystem functions (Wilson et al. 2017). Environmental DNA offers a means to broaden the scope of EIA to encompass a more coherent functional analysis of species and communities present. This will be useful to the emergence of system-based EIA frameworks.
Article Citation and journal link
Hinz, S., Coston-Guarini, J., Marnane, M., Guarini, J-M. 2022. Evaluating eDNA for use within marine environmental impact assessments. Journal of Marine Science and Engineering, 10: 375. doi:10.3390/jmse10030375.
Abstract
In this review, the use of environmental DNA (eDNA) within Environmental Impact Assessment (EIA) is evaluated. EIA documents provide information required by regulators to evaluate the potential impact of a development project. Currently eDNA is being incorporated into biodiversity assessments as a complementary method for detecting rare, endangered or invasive species. However, questions have been raised regarding the maturity of the field and the suitability of eDNA information as evidence for EIA. Several key issues are identified for eDNA information within a generic EIA framework for marine environments. First, it is challenging to define the sampling unit and optimal sampling strategy for eDNA with respect to the project area and potential impact receptor. Second, eDNA assay validation protocols are preliminary at this time. Third, there are statistical issues around the probability of obtaining both false positives (identification of taxa that are not present) and false negatives (non-detection of taxa that are present) in results. At a minimum, an EIA must quantify the uncertainty in presence/absence estimates by combining series of Bernoulli trials with ad hoc occupancy models. Finally, the fate and transport of DNA fragments is largely unknown in environmental systems. Shedding dynamics, biogeochemical and physical processes that influence DNA fragments must be better understood to be able to link an eDNA signal with the receptor’s state. The biggest challenge is that eDNA is a proxy for the receptor and not a direct measure of presence. Nonetheless, as more actors enter the field, technological solutions are likely to emerge for these issues. Environmental DNA already shows great promise for baseline descriptions of the presence of species surrounding a project and can aid in the identification of potential receptors for EIA monitoring using other methods.