Environmental DNA helps reveal reef shark distribution across a remote archipelago
Environmental DNA (eDNA) methods are being increasingly used in proof-of-concept studies to detect shark species, many populations of which are experiencing severe declines. These methods are widely seen as the future of biodiversity monitoring, but they have yet to become established as routine mon...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2023-10-01
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| Series: | Ecological Indicators |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1470160X23008609 |
| _version_ | 1797683122529107968 |
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| author | Nicholas Dunn David J. Curnick Chris Carbone Aaron B. Carlisle Taylor K. Chapple Rosalie Dowell Francesco Ferretti David M.P. Jacoby Robert J. Schallert Margaux Steyaert David M. Tickler Michael J. Williamson Barbara A. Block Vincent Savolainen |
| author_facet | Nicholas Dunn David J. Curnick Chris Carbone Aaron B. Carlisle Taylor K. Chapple Rosalie Dowell Francesco Ferretti David M.P. Jacoby Robert J. Schallert Margaux Steyaert David M. Tickler Michael J. Williamson Barbara A. Block Vincent Savolainen |
| author_sort | Nicholas Dunn |
| collection | DOAJ |
| description | Environmental DNA (eDNA) methods are being increasingly used in proof-of-concept studies to detect shark species, many populations of which are experiencing severe declines. These methods are widely seen as the future of biodiversity monitoring, but they have yet to become established as routine monitoring techniques for elasmobranch species. Here, we developed species-specific quantitative PCR assays for the detection of grey reef shark (Carcharhinus amblyrhynchos) and silvertip shark (Carcharhinus albimarginatus). We assessed whether species-specific eDNA methods could infer the distribution of the two species around the atolls of the Chagos Archipelago, which, despite being surrounded by a large marine protected area, experience contrasting levels of illegal fishing leading to heterogeneity in shark population densities. We found that eDNA detections were significantly reduced and sporadic around the northern atolls, which are under high pressure from illegal fishing. By contrast eDNA detections of both species were ubiquitous and consistent around the highly protected atoll Diego Garcia. We postulate that current levels of illegal, unreported and unregulated (IUU) fishing is having a significant impact on the shark community in the northern atolls and suppressing local reef shark populations. In the northern atolls we also employed visual and acoustic telemetry techniques to reveal the distribution of reef sharks. We found that despite eDNA samples being taken directly after visual surveys, detection results did not correlate, suggesting a need for further optimisation of eDNA methods for detecting sharks. However, both species were detected by eDNA in sites where they were not observed, highlighting that the scale of the sampling environment must be considered when inferring eDNA results and showing that eDNA methods can be used to fill gaps in data from more established monitoring techniques. We conclude that eDNA methods should be used in combination with other techniques to provide a complete picture of shark distribution so that threatened species can be better protected. |
| first_indexed | 2024-03-12T00:09:58Z |
| format | Article |
| id | doaj.art-35d8265d91c745df952622206eab5f50 |
| institution | Directory Open Access Journal |
| issn | 1470-160X |
| language | English |
| last_indexed | 2024-03-12T00:09:58Z |
| publishDate | 2023-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Ecological Indicators |
| spelling | doaj.art-35d8265d91c745df952622206eab5f502023-09-16T05:29:45ZengElsevierEcological Indicators1470-160X2023-10-01154110718Environmental DNA helps reveal reef shark distribution across a remote archipelagoNicholas Dunn0David J. Curnick1Chris Carbone2Aaron B. Carlisle3Taylor K. Chapple4Rosalie Dowell5Francesco Ferretti6David M.P. Jacoby7Robert J. Schallert8Margaux Steyaert9David M. Tickler10Michael J. Williamson11Barbara A. Block12Vincent Savolainen13Institute of Zoology, Zoological Society of London, London NW1 4RY, UK; Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UKInstitute of Zoology, Zoological Society of London, London NW1 4RY, UK; Corresponding author.Institute of Zoology, Zoological Society of London, London NW1 4RY, UKSchool of Marine Science and Policy, University of Delaware, Lewes, DE 19958, USAHatfield Marine Science Center, Oregon State University, 2030 SE Marine Science Drive Newport, OR 97365, USAInstitute of Zoology, Zoological Society of London, London NW1 4RY, UK; Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UKDepartment of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24060, USALancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UKHopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USAInstitute of Zoology, Zoological Society of London, London NW1 4RY, UK; Department of Zoology, University of Oxford, Oxford OX1 3SZ, UKSchool of Biological Sciences, The University of Western Australia, Crawley 6009, Western Australia, AustraliaInstitute of Zoology, Zoological Society of London, London NW1 4RY, UKHopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USAGeorgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UKEnvironmental DNA (eDNA) methods are being increasingly used in proof-of-concept studies to detect shark species, many populations of which are experiencing severe declines. These methods are widely seen as the future of biodiversity monitoring, but they have yet to become established as routine monitoring techniques for elasmobranch species. Here, we developed species-specific quantitative PCR assays for the detection of grey reef shark (Carcharhinus amblyrhynchos) and silvertip shark (Carcharhinus albimarginatus). We assessed whether species-specific eDNA methods could infer the distribution of the two species around the atolls of the Chagos Archipelago, which, despite being surrounded by a large marine protected area, experience contrasting levels of illegal fishing leading to heterogeneity in shark population densities. We found that eDNA detections were significantly reduced and sporadic around the northern atolls, which are under high pressure from illegal fishing. By contrast eDNA detections of both species were ubiquitous and consistent around the highly protected atoll Diego Garcia. We postulate that current levels of illegal, unreported and unregulated (IUU) fishing is having a significant impact on the shark community in the northern atolls and suppressing local reef shark populations. In the northern atolls we also employed visual and acoustic telemetry techniques to reveal the distribution of reef sharks. We found that despite eDNA samples being taken directly after visual surveys, detection results did not correlate, suggesting a need for further optimisation of eDNA methods for detecting sharks. However, both species were detected by eDNA in sites where they were not observed, highlighting that the scale of the sampling environment must be considered when inferring eDNA results and showing that eDNA methods can be used to fill gaps in data from more established monitoring techniques. We conclude that eDNA methods should be used in combination with other techniques to provide a complete picture of shark distribution so that threatened species can be better protected.http://www.sciencedirect.com/science/article/pii/S1470160X23008609eDNAElasmobranchIllegal fishingQuantitative PCRAcoustic telemetryUnderwater visual census |
| spellingShingle | Nicholas Dunn David J. Curnick Chris Carbone Aaron B. Carlisle Taylor K. Chapple Rosalie Dowell Francesco Ferretti David M.P. Jacoby Robert J. Schallert Margaux Steyaert David M. Tickler Michael J. Williamson Barbara A. Block Vincent Savolainen Environmental DNA helps reveal reef shark distribution across a remote archipelago Ecological Indicators eDNA Elasmobranch Illegal fishing Quantitative PCR Acoustic telemetry Underwater visual census |
| title | Environmental DNA helps reveal reef shark distribution across a remote archipelago |
| title_full | Environmental DNA helps reveal reef shark distribution across a remote archipelago |
| title_fullStr | Environmental DNA helps reveal reef shark distribution across a remote archipelago |
| title_full_unstemmed | Environmental DNA helps reveal reef shark distribution across a remote archipelago |
| title_short | Environmental DNA helps reveal reef shark distribution across a remote archipelago |
| title_sort | environmental dna helps reveal reef shark distribution across a remote archipelago |
| topic | eDNA Elasmobranch Illegal fishing Quantitative PCR Acoustic telemetry Underwater visual census |
| url | http://www.sciencedirect.com/science/article/pii/S1470160X23008609 |
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