3.2 Application of environmental DNA
Environmental DNA is a highly sensitive and efficient method for establishing the presence of species of any certain taxonomic group and for determining compositions of these communities (Pawlowski et al. 2021; Pascher et al. 2022). Therefore it can identify relatively rare species as well as circumvent potential difficulties in morphological identification of certain species.
In addition, eDNA is often a more non-intrusive and efficient sampling method (Ratcliffe et al. 2020). Therefore, eDNA sampling can potentially provide a higher sampling frequency, smaller grid size, and/or cover a larger geographical area. Sometimes, it can also be used in areas where other forms of sampling can be challenging. These characteristics of eDNA methods can support the vital efforts to produce time series estimated to be of vital importance for detecting changes in the marine ecosystems (Benway et al. 2019; Bianchi et al. 2022).
Because marine monitoring has been performed using other methods that can be time consuming and challenging, the notion that eDNA methods might be able to partially replace or complement some of these methods for a more efficient monitoring has interested both researchers and stakeholders (Hinz et al. 2022; Ramirez-Amaro et al. 2022). This has also resulted in the need of comparing eDNA methods to these more traditional methods (Closec et al. 2019; Fediajevaite et al. 2021; Keck et al. 2022).
In this process, misunderstandings have sometimes developed about the potential and application of eDNA. Essentially, it has resulted in a tendancy for some stakeholders to expect that eDNA methods could serve as a replacement for some of the traditional and more expensive methods, instead of evaluating how the methods complement each other and can together provide better monitoring, which many recommended (Ruppert et al. 2019; Rogers et al. 2022; Rourke et al. 2022; Suarez-Bregua et al. 2022).
Although eDNA methods often perform well in comparison with traditional surveys (Chavez et al. 2021; Fediajevaita et al. 2021; Keck et al. 2022), researchers also struggle to provide the clear-cut results that stakeholders need in order to justify investing in eDNA-based reasearch and monitoring. Improved communication is a key issue for stakeholders to gain the understanding that eDNA methods, as all other methods, have strenghts and challenges that need to be taken into consideration.
Therefore, the challenge for all parties is to get a common understanding of the great potential of eDNA methods and apply these to marine monitoring in a fruitful manner, without complicating the process of implementation with unrealistic expectations and requirements.
3.3 Global and large-scale initiatives
In marine resource management, the methods commonly used are based on observations, capture, or bulk sampling for morphological classification and enumeration. These traditional methods are and have been essential for providing data for knowledge-based management of the marine environment. However, these methods have some limitations such as the constraint on sample frequency and geographical area covered due to the nature of the sampling method and/or the time consuming process of morpho-taxonomic identification and enumeration. The application of eDNA can address these and other issues and can provide a valuable complementary approach.
The potential in the application of eDNA to supplement and improve environmental monitoring has despite standardization challenges inspired many large national and international institutions to start the process of implementation. As an example, the American Agency NOAA (National Oceanic and Atmospheric Administration), renowned for its scientific work and services in climate monitoring and fisheries management amongst other things, has recognised the potential in eDNA methods to supplement other more traditional methods used to produce valuable survey data. Amongst other applications, the agency recommends commencing implementation of eDNA methods to support Ecosystem-Based Fisheries management (UNIG 2020)
The current loss of Biodiversity has also inspired UNESCO to launch a global eDNA project to study vulnerability of species to climate change at marine World Heritage sites, recognized for their unique biodiversity, outstanding ecosystems, or for representing major stages in Earth’s history (
https://www.unesco.org/en/edna-expeditions). The aim is to measure the vulnerability of marine biodiversity to climate change and the impacts of that change on the distribution and migration patterns of marine life across marine World Heritage sites. This knowledge will help understand global trends and inform ongoing efforts to protect marine ecosystems and ensure future generations continue to enjoy the services they provide.
The Ocean Biomolecular Observing Network (OBON) also uses eDNA methods to greatly enhance coastal and open ocean biodiversity observations (
https://www.obon-ocean.org/). The program utilizes biomolecular technologies to monitor, research and understand life in the sea at every trophic level and scale, how life varies in response to climate and anthropogenic impacts, including fisheries, and how these changes impact society.
Various other initiatives have also been made to instigate more coordinated efforts in implementation of eDNA methods. As an example, the European network DNAqua-Net (COST Action CA15219) presented a suggested roadmap for successful implementation of DNA-based biomonitoring for freshwater ecosystems (Blancher et al. 2022). Although focused on freshwater monitoring, it provides valuable reflections of relevance for the marine environment. Their paper gives an “overview of the forum discussions and common European views that emerged from them, while reflecting the diversity of situations in different countries”. They recognized that implementing DNA-based methods in biomonitoring will require significant technical and organisational changes and that their adoption will require coordinated actions at national and international levels.
Another initiative is the European Marine Omics Biodiversity Observation Network (EMO-BON), which focuses on marine monitoring and including eDNA methods in its approach (
https://www.embrc.eu/emo-bon). EMO BON aims to establish a coordinated, long-term, marine biodiversity observatory. By bringing together individual biological observation stations, EMBRC provides the context and opportunity for partner institutions to participate in EMO BON and build a modern biodiversity observation framework for Europe. Currently, EMO BON includes 16 marine stations, located from the Arctic to the Red Sea.
3.4 Nordic initiatives
Nordic institutions and researchers are involved in many international initiatives applying eDNA methods to marine research and monitoring and in the recent years, there has been a steady increase in the application of eDNA methods to marine research in the Northeast Atlantic (Salter et al. 2019; Turon et al. 2022; Pampoulie et al. 2023). However, there has been little consistency in the methodology as different projects follow different protocols for sampling, storage, data management etc. that are estimated to be most appropriate at the time.
This is causing difficulties in conforming to a gold standard when initiating eDNA based monitoring of the marine environment since there are no standard guidelines to follow for the application of eDNA methods. It is also hampering fruitful collaboration between the Nordic countries in the process of implementation eDNA methods in marine monitoring.