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Developing environmental DNA methods to assess the distribution of cryptic sharks and rays

OPL team members involved

Nick Dunn & David Curnick


Imperial College London & Stanford University


Chagos Archipelago


2018 - 2022

Project description

Detecting macroorganisms from genetic material in environmental samples, otherwise known as environmental DNA or eDNA, is becoming a widespread area of research. Methods for sampling and extracting eDNA from environmental samples have rapidly developed over the last decade, allowing researchers to detect rare and critically endangered species, monitor whole communities and derive useful genetic data from target organisms without having to even see the animals in question.


Nick’s project builds on these advances to develop methods to detect elasmobranch species in the large Marine Protected Area around the Chagos Archipelago and focuses on the following objectives;

  1. Develop assays that are able to detect DNA from two key shark species, Grey reef sharks (Carcharhinus amblyrhynchos) and silvertip sharks (C. albimarginatus), in environmental samples and use these assays to identify snapshots of their distribution across the archipelago.

  2. Use eDNA metabarcoding to investigate fish and elasmobranch communities around Diego Garcia atoll, identifying species of interest and looking at how communities differ between sampling depth and location.

  3. Establish methods for combining eDNA detection metrics with data derived from more established monitoring techniques such as visual surveys and acoustic monitoring arrays.

  4. Develop computational particle tracking techniques that can be used alongside hydrodynamic modelling to investigate the potential origins of eDNA following detection.

 The overarching goal of this project is to advance the field of eDNA for the detection of elasmobranch species so that eDNA methods can be implemented in conservation and management toolkits for the monitoring of these charismatic but endangered species.


Main - PhD student Nick Dunn collecting eDNA sample around the Chagos Archipelago (Image courtesy of Margaux Steyaert). Insert - A electrophoresis gel image following  PCR (Image courtesy of Nick Dunn)

Recent publications

  • Johri, S., Dunn, N., Chapple, T.K., Curnick, D., Savolainen, V., Dinsdale, E.A. and Block, B.A., 2020. Mitochondrial genome of the Silvertip shark, Carcharhinus albimarginatus, from the British Indian Ocean Territory. Mitochondrial DNA Part B, 5(3), pp.2085-2086.

  • Dunn, N., Johri, S., Curnick, D., Carbone, C., Dinsdale, E.A., Chapple, T.K., Block, B.A. and Savolainen, V., 2020. Complete mitochondrial genome of the gray reef shark, Carcharhinus amblyrhynchos (Carcharhiniformes: Carcharhinidae). Mitochondrial DNA Part B, 5(3), pp.2080-2082.

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