Community structure and spatial distribution of vent fauna in the hydrothermal fields of North Fiji Basin based on ROV visual survey

Abstract

This study was conducted to investigate the community structure and distributional pattern of hydrothermal and adjacent deep-sea fauna at two hydrothermal vent fields (KF2 and KF3) on the central spreading axis in North Fiji Basin, from November to December 2016. Parts of these areas have been explored previously locating vent community sites named ‘White Lady’ and ‘Mussel Valley’. This study further investigates KF2 and KF3 areas thoroughly, which extends the regions from previously found vent sites by visual inspections. During the ROV surveys by ROPOS, we obtained a total of ~160 hrs of video clips and ~14,000 still images along with specimen samples. In these areas, more than 30 species from active andinactive vent sites were identified and most taxa showed. In Active hydrothermal vent area, 2 kinds of mussel Bathymodiolus sp. and limpet Lepetodrilus sp., 2 kinds of snail Ifremeria sp., Alviniconcha sp. were observed. In Annelida tax, scaly worm Branchinotogluma sp. and Provinella sp. were dominant on the surface of hydrothermal chimney. In Arthropoda taxa, Munidopsis sp. and Paralomis hiretella, Austinograea sp. and Nautilocaris sp. were major fauna near hydrothermal vent area. In inactive vent area of common deep-sea area, 4 kinds of cnidarian Actiniaria, Chrysogorgia sp. Primnoidae sp. were observed. In mollusca taxa, smail Turridae sp. and 2 kinds of octopus Octopodidae sp. were also observed. Swimming h