34 DECEMBER 2023 • WORLD AQUACULTURE • WWW.WAS.ORG These observations are confirmed in a paper by Nevers et al. (2020). The authors conducted a series of field and controlled mesocosm experiments to examine the detection and accumulation of eDNA in sediment and water and the transport of eDNA in a small stream in the Lake Michigan watershed, using the invasive round goby (Neogobius melanostomus) as a DNA source. They reported round goby eDNA accumulated and decayed more slowly in sediment than water. In the stream, DNA shedding was markedly lower than calculated in the laboratory, but their modeling indicated eDNA could potentially travel long distances (up to 50 km) under certain circumstances. Collectively, these findings show that the interactive effects of ambient conditions (e.g., eDNA stability and decay, hydrology, settling and re-suspension) are critical to consider when developing regulatory sampling programs to avoid erroneously concluding species are present. Guilfoyle and Schultz (2017) and Guilfoyle et al. (2017) demonstrated silver carp (Hypophthalmichthys molitrix) were a prey species for the double-crested cormorant (Phalacrocorax auritus) and then estimated silver carp eDNA loading to waters above the electric barriers on the Chicago Sanitary and Ship Canal via double-crested cormorant feces. Their study indicates piscivorous birds are potentially important sources of silver carp DNA when live fish are not present. In addition, the biology and physiology of the target animal may influence detection. Adams et al. (2019) sampled four lentic ponds with different densities (0 kg/ha, 6 kg/ha, 9 kg/ha, and 13 kg/ha) of painted turtles (Chrysemys picta) over three months to detect differences in eDNA using a quantitative polymerase chain reaction assay amplifying the cytochrome oxidase I region of painted turtle mitochondrial DNA. Only one sample of the highest-density pond amplified eDNA for a positive detection. Ethical and Legal Issues Using eDNA for marine turtle population studies, Whitmore et al. (2023) realized they were inadvertently collecting human genomic information that they termed human genetic bycatch (HGB). They noted, “…human DNA is rarely (if ever) the intended target of eDNA [wildlife population] studies, leaving the field with a lack of specific human-related regulatory guidelines or ethical approvals.” Triggered by this epiphany, the authors conducted a series of samplings in environmental water from sites distant from and close to human habitation, from human footprints in beach sand and from occupied and unoccupied room air. The authors reported HGB was found in all field eDNA samples. “These samples had been collected primarily for the detection of non-human species, marine turtles, animal pathogens and metagenomics. With no human enrichment prior to shotgun sequencing and with sampling having been conducted in areas of relatively low human habitation densities, we nevertheless inadvertently captured a substantial amount of human genomic data.” The authors then discussed potential ethical and legal unintended consequences (lack of consent/breach of privacy, publicly accessible storage of eDNA samples, inadvertent individual tracking or genome harvesting). In sampling eDNA on aquaculture farms and facilities, it appears likely that the DNA of farm personnel will also be collected and stored, potentially for future uses, as long-term storage of eDNA samples has been advocated (Jarman et al. 2018; Zizka et al. 2022). Scientists working with eDNA have long known that human DNA could be found in samples; typically, this is simply excluded. In fact, human and domestic animal DNA can be found in negative control libraries and PCR mixes (Thaler et al. 2023). Only with the publication of Whitmore et al. (2023) did eDNA scientists and others come to the curiously belated realization that capturing human DNA raises significant ethical issues. Summary Environmental DNA methods and applications are advancing rapidly. There is great potential for useful applications in aquaculture, but also substantial risks. Our purpose in highlighting the issues of uncertainties, potential regulatory use, and human DNA bycatch, is to encourage the active participation of aquaculture scientists, farmers, and associated businesses in shaping legislation and regulations to ensure appropriate and ethical uses of eDNA. Until governments and institutions invoke restrictions or protections for human genetic bycatch, simple questions should be posed to the eDNA samplers: Do you obtain permission? What are your policies and practices to securely store or share samples? Bruce et al. (2021) utilized a continent-wide approach to capture experienced eDNA user knowledge to inform an electronic handbook. We suggest the World Aquaculture Society could play a similar role, as exemplified by Bruce et al. (2021), to aggregate the rapidly evolving global knowledge and experience to produce an assessment that will thoroughly and objectively inform eDNA aficionados and novices, governmental agency leadership and program managers, and most importantly the public as to the practicalities and impracticalities of using eDNA to detect and manage invasive species. Notes Paul Zajicek*, Executive Director, National Aquaculture Association, PO Box 12759, Tallahassee, FL 32317, Nathan Stone, Engle-Stone Aquatic$ LLC, Strasburg, VA 22657 * Corresponding author: paul@nationalaquaculture.org References Adams, C.I.M, L.A. Hoekstra, M.R. Muell and F.J. Janzen. 2019. A brief review of non-avian reptile environmental DNA (eDNA), with a case study of painted turtle (Chrysemys picta) eDNA under field conditions. Diversity 11(4): 50. Bass, D., K.W. Christison, G.D. Stentiford, L.S.J. Cook and H. Hartikainen. 2023. Environmental DNA/RNA for pathogen and parasite detection, surveillance, and ecology. Trends in Parasitology, April; 39(4): 285-304. Bruce, K., R. Blackman, S.J. Bourlat, A.M. Hellstrom, J. Bakker, I. Bista, K. Bohmann, A. Bouchez, R. Brys, K. Clark, V. Elbrecht, S. Fazi, V. Fonseca, B. Hanfling, F. Leese, E. Machler, A.R. Mahon, K. Meissner, K. Panksep, J. Pawlowski, P. Schmidt Yanez, M. Seymour, B. Thalinger, A. Valentini, P. Woodcock, M. Traugott, V. Vasselon and K. Deiner, 2021. A practical guide to DNAbased methods for biodiversity assessment. Advanced Books. Pensoft Publishers (https://ab.pensoft.net/article/68634/ accessed September 29, 2022).
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