Eualus amandae (Deacapoda: Caridea: Thoridae) is an indicator of active venting sites in the Southern Ocean

We report in situ observations that reveal the presence of the thorid genus Eualus at hydrothermally active sites. The shrimp Eualus amandae Nye, Copley & Linse, 2013 was first collected in non-venting sites but near areas of hydrothermal activity, on the East Scotia Ridge segment E9 and in the Kemp Caldera, South Sandwich Arc. During a recent expedition of RV Polarstern, specimens of Eualus amandae were observed via a remotely operated vehicle (ROV) at the East Scotia Ridge segment E2 and Kemp Caldera. The animals were seen in shimmering water sites on pillow basalts and at active hydrothermal orifices, both unambiguously hydrothermally active. These sites were also characterised by other vent marginal fauna, such as deep-water comatulid crinoids or stoloniferean cnidarians. The shrimp family Thoridae is more diverse in Antarctic waters than other shrimp families and these records suggest two independent origins of hydrothermal-related habitats in Lebbeus, and now Eualus. These records expand the understanding of the contribution of geothermal activity to larger patterns of Antarctic deep-sea biodiversity.

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