Abstract
BackgroundEnvironmental DNA (eDNA) is an effective tool for the detection and monitoring of presence or absence of rare and invasive species. These techniques have been extended to quantify biomass in vertebrates, particularly in fish species. However, the efficacy of eDNA techniques to quantify biomass in invertebrate species has rarely been examined. This study tested whether eDNA could be used to determine the biomass of the world-wide invasive green crab, Carcinus maenas. In a controlled laboratory study, the relationship between biomass and C. maenas eDNA concentration was examined in the context of different biotic (activity) and abiotic (temperature) parameters.ResultsWhen incubating different numbers of crabs in sterile saltwater for up to 7 days, a relationship between eDNA concentration and biomass was observed at temperatures of 6.7 ℃ and 18.7 ℃, but not at 12.8 ℃. Additionally, motor activity, aggression level, time of sampling, and features of organismal decay had significant impact on the concentration of C. maenas eDNA collected.ConclusionsWe show that eDNA concentration did not correlate with biomass, and that biomass, temperature, organismal characteristics, and potentially many more parameters affect shedding and degradation rates for eDNA in this species, thus, impacting the recoverable eDNA concentration. Therefore, eDNA techniques are not likely to provide a reliable signal of biomass in the invasive invertebrate species C. maenas.
Highlights
Environmental DNA is an effective tool for the detection and monitoring of presence or absence of rare and invasive species
The first part of our study examined the relationship between C. maenas Environmental DNA (eDNA) concentration and C. maenas density (1, 3, and 6 crabs), and how this relationship is impacted by seawater temperatures (6.7 °C, 12.8 °C, and 17.8 °C), the range of which was chosen to reflect changes in the yearly average water temperature observed in the Gulf of Maine [41, 42]
Overall, our study shows that various abiotic and biotic parameters alter the concentration of C. maenas eDNA in the water, via increasing or decreasing shedding and degradation rates
Summary
Environmental DNA (eDNA) is an effective tool for the detection and monitoring of presence or absence of rare and invasive species. These techniques have been extended to quantify biomass in vertebrates, in fish species. Danziger et al BMC Ecology and Evolution (2022) 22:14 of eDNA within the environmental matrix These processes are affected by hydrology (for eDNA sampling conducted in water), biology and ecology of the organism, stress levels (i.e., causing metabolic changes and differences in rate of release of eDNA), abiotic factors, and other biotic factors [2, 14, 15]. Some examples of abiotic factors which affect eDNA include UV light, temperature, and salinity, while other biotic factors include enzyme or microbialinduced degradation [4, 16, 19, 20]
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