Megabenthic assemblages at the southern Central Indian Ridge – Spatial segregation of inactive hydrothermal vents from active-, periphery- and non-vent sites

• Published in: Marine environmental research Vol. 151; p. 104776
• Main Authors: Gerdes, K.H., Martínez Arbizu, P., Schwentner, M., Freitag, R., Schwarz-Schampera, U., Brandt, A., Kihara, T.C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-10-2019; Elsevier BV
• Subjects: Active hydrothermal vent; Animals; Biodiversity; Cluster analysis; Clustering; Ecosystem; Effluents; Fauna; Faunal assemblage; GIS mapping; Hydrothermal plumes; Hydrothermal springs; Hydrothermal Vents; Inactive hydrothermal vent; Megafauna; Mining; Ocean floor; Photograph and video imagery; Protected areas; Redundancy; Segregation; Southern central indian ridge; Substrates; Sulfide; Sulfides; Sulphides; Underwater exploration; Vents; Zonation; Inactive hydrothermal vent; Faunal assemblage; Active hydrothermal vent; Southern central indian ridge; Megafauna; Photograph and video imagery; GIS mapping
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2019.104776

Active hydrothermal vents are small-scale habitats hosting endemic fauna in a well-defined zonation around fluid effluents. The fauna of inactive hydrothermal vents and its relation to active vents and non-vent area is poorly known. Characterizing inactive areas is prerequisite to establish protected areas, especially in the context of potential seafloor massive sulfide mining, which targets inactive sites. Hierarchical clustering and Distance-based Redundancy Analysis revealed five assemblages, with significantly associated substrate types: I) active hydrothermal vent, II) periphery, III) inactive hydrothermal vent and IV) soft- and V) hard-substrate within the non-vent area. For the first time, a unique inactive faunal assemblage could be identified within the hydrothermally extinct inactive Gauss field and on adjacent hard substrates. The spatial separation from the active Edmond field and periphery and the non-vent area indicates the existence of an inactive assemblage.
•Five faunal assemblages linked to active vent, periphery, inactive vent and the non-vent soft- and hard substrates.•Delineation of inactive faunal assemblage from inactive parts in active vent, periphery and non-vent hard substrates.•Inactive sulfide deposits inhabited by distinct faunal assemblage without endemic taxa.•Establishment of Marine Protected Areas needs to include inactive hydrothermal vents.