A Global Red List for Hydrothermal Vent Molluscs

Aoife Molloy,Nova B Hanson,Elin A Thomas,Julia D Sigwart,Monika Böhm,Mary Seddon

doi:10.3389/fmars.2021.713022

Abstract

With the accelerating development of direct and indirect anthropogenic threats, including climate change and pollution as well as extractive industries such as deep-sea mining, there is an urgent need for simple but effective solutions to identify conservation priorities for deep-sea species. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is an effective and well-recognized tool to promote the protection of species and presents an opportunity to communicate conservation threats to industry, policy makers, and the general public. Here, we present the Vent Red List for molluscs: a complete global assessment of the extinction risk of all described molluscs endemic to hydrothermal vents, a habitat under imminent threat from deep-sea mining. Of the 184 species assessed, 62% are listed as threatened: 39 are Critically Endangered, 32 are Endangered, and 43 are Vulnerable. In contrast, the 25 species that are fully protected from deep-sea mining by local conservation measures are assessed as Least Concern, and a further 45 species are listed as Near Threatened, where some subpopulations face mining threats while others lie within protected areas. We further examined the risk to faunas at specific vent sites and biogeographic regions using a relative threat index, which highlights the imperiled status of vent fields in the Indian Ocean while other vent sites within established marine protected areas have a high proportion of species assessed as Least Concern. The Vent Red List exemplifies how taxonomy-driven tools can be utilized to support deep-sea conservation and provides a precedent for the application of Red List assessment criteria to diverse taxa from deep-sea habitats.

Highlights

As a vast and relatively unexplored ecosystem, the deep sea presents unique conservation challenges
Despite several studies concluding that mining will have an adverse and often irreversible impact on local deep-sea biodiversity (e.g., Gollner et al, 2017; Van Dover et al, 2017; Niner et al, 2018; Simon-Lledó et al, 2019), very few conservation measures have been implemented to date
Of the 184 vent-endemic mollusc species assessed for the Vent Red List, 114 (62%) are assessed as threatened by deep-sea mining, and a further 45 (24.4%) are listed as Near Threatened (Table 2, Figure 1, and Supplementary Material 1)

Summary

Introduction

As a vast and relatively unexplored ecosystem, the deep sea presents unique conservation challenges. While the seafloor is home to incredible life, it is characterized by large quantities of commercially valuable minerals including polymetallic sulfides at hydrothermal vents, manganese nodules on abyssal plains, and cobalt-rich ferromanganese crusts on seamounts (Hein et al, 2013; Petersen et al, 2016). The mining of these deep-sea environments and their resources is being widely considered, and in some cases instigated (Okamoto et al, 2019), as demand for industrially important metals grows and technological capabilities improve (Sharma, 2011, 2015). Despite several studies concluding that mining will have an adverse and often irreversible impact on local deep-sea biodiversity (e.g., Gollner et al, 2017; Van Dover et al, 2017; Niner et al, 2018; Simon-Lledó et al, 2019), very few conservation measures have been implemented to date

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