Environmental DNA reveals tropical shark diversity in contrasting levels of anthropogenic impact

Judith Bakker,Dayne Buddo,David Mouillot,Germain Boussarie,Heidi Hertler,Stefano Mariani,Demian D Chapman,Laurent Vigliola,Owen S Wangensteen,Tristan L Guttridge

doi:10.1038/s41598-017-17150-2

Abstract

Sharks are charismatic predators that play a key role in most marine food webs. Their demonstrated vulnerability to exploitation has recently turned them into flagship species in ocean conservation. Yet, the assessment and monitoring of the distribution and abundance of such mobile species in marine environments remain challenging, often invasive and resource-intensive. Here we pilot a novel, rapid and non-invasive environmental DNA (eDNA) metabarcoding approach specifically targeted to infer shark presence, diversity and eDNA read abundance in tropical habitats. We identified at least 21 shark species, from both Caribbean and Pacific Coral Sea water samples, whose geographical patterns of diversity and read abundance coincide with geographical differences in levels of anthropogenic pressure and conservation effort. We demonstrate that eDNA metabarcoding can be effectively employed to study shark diversity. Further developments in this field have the potential to drastically enhance our ability to assess and monitor elusive oceanic predators, and lead to improved conservation strategies.

Highlights

Citation Bakker, J, Wangensteen, OS, Chapman, DD, Boussarie, G, Buddo, D, Guttridge, TL, Hertler, H, Mouillot, D, Vigliola, L and Mariani, S (2017) Environmental DNA reveals tropical shark diversity in contrasting levels of anthropogenic impact
Even though several molecular operational taxonomic units (MOTUs) are shared between the two regions, there is still a clear spread in MOTU composition between New Caledonia and the Caribbean
The results show that none of the Caribbean (Fig. 4a) or New Caledonian (Fig. 4b) samples tend to reach a plateau in MOTU richness, with the exception of the Bahamas, the Caribbean slopes tend to flatten after N = 10

Summary

Introduction

Citation (please note it is advisable to refer to the publisher’s version if you intend to cite from this work) Bakker, J, Wangensteen, OS, Chapman, DD, Boussarie, G, Buddo, D, Guttridge, TL, Hertler, H, Mouillot, D, Vigliola, L and Mariani, S (2017) Environmental DNA reveals tropical shark diversity in contrasting levels of anthropogenic impact. Sharks are charismatic predators that play a key role in most marine food webs Their demonstrated vulnerability to exploitation has recently turned them into flagship species in ocean conservation. We demonstrate that eDNA metabarcoding can be effectively employed to study shark diversity Further developments in this field have the potential to drastically enhance our ability to assess and monitor elusive oceanic predators, and lead to improved conservation strategies. Elasmobranch (sharks and batoids) populations have suffered from overexploitation and stock declines[4,5,6,7,8,9] They are key species in virtually all marine trophic webs[10,11] and have long been in conflict with human societies, due to their perceived competition with fishers[12] or hazardous nature[13,14]. Recently have elasmobranchs become the focus of conservation initiatives[4,19], as the importance of these charismatic animals for the maintenance and resilience of healthy ecosystems is widely acknowledged[20,21,22,23]

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Results

Conclusion