Peripheral communities of the Eastern Lau Spreading Center and Valu Fa Ridge: community composition, temporal change and comparison to near‐vent communities

Abstract

Western Pacific hydrothermal vents will soon be subjected to deep-sea mining and peripheral sites are considered the most practical targets. The limited information on community dynamics and temporal change in these communities makes it difficult to anticipate the impact of mining activities and recovery trajectories. We studied community composition of peripheral communities along a cline in hydrothermal chemistry on the Eastern Lau Spreading Center and Valu Fa Ridge (ELSC-VFR) and also studied patterns of temporal change. Peripheral communities located in the northern vent fields of the ELSC-VFR are significantly different from those in the southern vent fields. Higher abundances of zoanthids and anemones were found in northern peripheral sites and the symbiont-containing mussel Bathymodiolus brevior, brisingid seastars and polynoids were only present in the northern peripheral sites. By contrast, certain faunal groups were seen only in the southern peripheral sites, such as lollipop sponges, pycnogonids and ophiuroids. Taxonomic richness of the peripheral communities was similar to that of active vent communities, due to the presence of non-vent endemic species that balanced the absence of species found in areas of active venting. The communities present at waning active sites resemble those of peripheral sites, indicating that peripheral species can colonize previously active vent sites in addition to settling in the periphery of areas of venting. Growth and mortality were observed in a number of the normally slow-growing cladorhizid stick sponges, indicating that these animals may exhibit life history strategies in the vicinity of vents that differ from those previously recorded. A novel facultative association between polynoids and anemones is proposed based on their correlated distributions.

Detailed Mapping of Hydrothermal Vent Fauna: A 3D Reconstruction Approach Based on Video Imagery

“…The diversity of the Mara4 assemblage could be the result of mixing vent endemic, non-symbiont reliant or not solely reliant species, such as A. rodriguezensis or B. septemdierum, in lower abundances, with filter feeding, carnivorous and scavenging taxa to form this peripheral community (Fabri et al, 2011;Sen et al, 2016;Goffredi et al, 2017). It has been suggested that anemones can tolerate low levels of hydrothermal fluids and temperatures, which has been measured for M. rimicarivora with a maximum tolerance of 25 • C at Ashadze vent field on the MAR (Fabri et al, 2011).…”

“…In general, the faunal zonation can be divided in an active vent fauna consisting of symbiotic taxa occurring close to fluid exits, often dominated by a single taxon in a distance related gradient according to their temperature tolerance and ability to persist in toxic fluid effluents (Sarrazin et al, 1997;Podowski et al, 2009;Sen et al, 2014), and mainly endemic secondary consumer vent taxa at greater distances to fluid effluents. The increasing distance to the active vent field results in a mix of vent taxa and background taxa in high abundances (Podowski et al, 2010;Marsh et al, 2012;Sen et al, 2016). This distance related taxonomic gradient has been studied in detail at the East Pacific Rise for hydrothermal vent communities, specifically after disturbance events (Tunnicliffe et al, 1997), for several gastropod species (Bates et al, 2005) and zooplankton distribution (Skebo et al, 2006).…”

“…Those studies detecting and defining the faunal assemblage structure of hydrothermal vent fields used video annotations (Goffredi et al, 2017) or combined images to build a 2D photomosaic (Podowski et al, 2009;Fabri et al, 2011;Marsh et al, 2012;Du Preez and Fisher, 2018). Likewise, imagery based studies were conducted to observe succession stages (Sarrazin et al, 1997;Shank et al, 1998;Sen et al, 2014Sen et al, , 2016 and long-term variations (Cuvelier et al, 2011;Du Preez and Fisher, 2018) of faunal assemblages on active venting edifices. These studies reveal the importance of temperature as hydrothermal fluid proxy for symbiotic taxa and their zonation.…”

A review of the brachyuran deep-sea vent community of the western Pacific, with two new species of Austinograea Hessler & Martin, 1989 (Crustacea, Decapoda, Brachyura, Bythograeidae) from the Lau and North Fiji Back-Arc Basins

“…Austinograea williamsi was originally collected in abundance on three active vent fields along the crest of the spreading center, at about latitude 18°N and longitude 144°E, 3600 m depth; later found on vent sites of the Mariana Trough at 13°23.7'N, 143°55.2'E, about 1450 m depth, andat 18°12.9'N, 144°42.5'E, about 3600 m depth (Hessler et al 1988;Hessler & Martin 1989;Guinot 1990;Hessler & Lonsdale 1991;Tsuchida & Fujikura 2000;Tsuchida & Hashimoto 2002;Martin & Haney 2005;Segonzac 2006;McLay 2007;Ng et al 2008;Zelnio & Hourdez 2009;Hamasaki et al 2010: fig. 1;Podowski et al 2010;Sen et al 2013Sen et al , 2014Sen et al , 2016Kojima & Watanabe 2015). Records of A. williamsi from the Lau and North Fiji Back-Arc Basins appear to be quite doubtful and at the very least need to be checked.…”

“…; Hashimoto et al 1989, as bythograeid sp. ;Guinot 1990in Desbruyères & Segonzac 1997Galkin 1997;Tsuchida & Hashimoto 2002;Komai & Segonzac 2004;Martin & Haney 2005;López-González et al 2005;Segonzac 2006;Guinot & Segonzac 2006a, b;Desbruyères et al 2006b;McLay 2007;Shields & Segonzac 2007;Ng et al 2008;Erickson et al 2009;Corbera & Segonzac 2010;Podowski et al 2010;Mateos et al 2012;Kim et al 2013Kim et al , 2014Sen et al 2013Sen et al , 2014Sen et al , 2016Yang et al 2013;Hui et al 2017). Some of these records, however, deserve to be checked.…”