Freshwater Pathways: How Water Movement Aids in the Dissemination of Environmental DNA Across Terrains

Photograph: Dr. Joanne Littlefair procuring a sample from a lakeside for subsequent scrutiny for environmental DNA. Acknowledgment: Rachel Henderson

A scientific investigation has shed light on the significant role of environmental DNA (eDNA) for monitoring biodiversity within freshwater ecosystems. The research, conducted in Canadian lakes, underscored the necessity of comprehending the interconnectedness of water bodies for efficient eDNA surveillance, advocating for additional research to fine-tune its usage.

An article, recently published in the Proceedings of the Royal Society B, employed the technique of environmental DNA metabarcoding to examine communities of fish and zooplankton. The research illustrated that the exchange of water among distinct freshwater habitats, termed freshwater connectivity, is instrumental in the dispersal of eDNA. This fact underscores the potential of eDNA to afford a holistic understanding of freshwater biodiversity.

Interconnected Water Systems and DNA Surveillance

Waterways serve as conduits connecting various aquatic ecosystems, thereby facilitating the migration of organisms such as fish and plants. While such connectivity bolsters the vitality of aquatic communities, it concurrently complicates efforts to trace the DNA of these entities.

Research Outcomes and Their Connotations

Led by Dr. Joanne Littlefair, an academic in the field of biological sciences at Queen Mary University of London, the study focused on a cluster of 21 lakes located within Canada’s Boreal Forest at the IISD Experimental Lakes Area. The research findings indicated that eDNA within individual lakes largely corresponded with the habitat proclivities of the species in question. Nevertheless, there was evidence that some eDNA was carried over to downstream water bodies. Lakes with greater interconnectedness showed more instances of unexplained eDNA detections when compared to traditional surveillance methods.

The study was undertaken at the IISD-Experimental Lakes Area, a prominent freshwater ecosystem research center situated in Ontario, Canada. Lakes with notable connections were chosen for scrutiny to better understand how environmental DNA propagates throughout the terrain. Credit: IISD-ELA

The outcomes of the research bear implications for leveraging eDNA as a mechanism for monitoring biodiversity within freshwater environments. While eDNA presents a potent instrument for such monitoring, the data must be evaluated in the context of the interconnectedness of the landscape.

Expert Views and Future Directions for Research

“eDNA allows for the identification of species that are traditionally challenging to monitor, encompassing invasive and endangered species,” stated Dr. Littlefair. “Our findings suggest that the design of eDNA surveys should account for the specific connectivity of the freshwater ecosystem under study. In ecosystems with high connectivity, sample collection from a range of locales is imperative for constructing a comprehensive view of existing biodiversity.”

The research also accentuates the necessity for additional studies focusing on the factors—like the kinetics of water—that affect the spatial precision of eDNA identification. For instance, in ecosystems where water circulates rapidly, increased sampling may be required to boost the likelihood of eDNA detection. Such studies will contribute to enhancing scientific comprehension of the utility of eDNA for the conservation and monitoring of aquatic biodiversity.

Reference: The article titled “Freshwater Connectivity Transforms Spatially Integrated Signals of Biodiversity” was co-authored by Joanne E. Littlefair, José S. Hleap, Vince Palace, Michael D. Rennie, Michael J. Paterson, and Melania E. Cristescu, and was published on September 13, 2023, in Proceedings of the Royal Society B Biological Sciences. DOI: 10.1098/rspb.2023.0841

The research was financially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the WSP Montreal Environment department. It was a collective effort involving scholars from Queen Mary University of London in the United Kingdom and several Canadian institutions, including McGill University, Lakehead University, IISD Experimental Lakes Area, and SHARCNET. During the course of the study, Dr. Littlefair was affiliated with both McGill University and QMUL.

Frequently Asked Questions (FAQs) about Environmental DNA (eDNA) in Freshwater Biodiversity Monitoring

More about Environmental DNA (eDNA) in Freshwater Biodiversity Monitoring

• Proceedings of the Royal Society B Biological Sciences
• IISD Experimental Lakes Area
• Natural Sciences and Engineering Research Council of Canada (NSERC)
• Queen Mary University of London, School of Biological and Chemical Sciences
• Environmental DNA: An Overview
• Canadian Boreal Forest
• WSP Montreal Environment Department
• McGill University
• Lakehead University
• SHARCNET