Biotic and abiotic factors affecting distributions of megafauna in diffuse flow on andesite and basalt along the Eastern Lau Spreading Center, Tonga

Abstract

Imagery and environmental data from 7 diffuse flow hydrothermal vent sites along the Eastern Lau Spreading Center (ELSC) are used to constrain the effects of lava type, temperature, chemistry, and biological interactions on faunal distributions. Of the species with chemoautotrophic endosymbionts, the snail Alviniconcha spp. occupies habitats with the greatest exposure to vent fluids. Temperatures exceeding 45°C define its upper limit of exposure to vent flow, and minimum sulfide requirements constrain its lower limits. The mussel Bathymodiolus brevior experiences the least exposure to vent flow; temperatures of about 20°C determine its upper limit, while its lower limit is defined by its minimum sulfide requirements. The snail Ifremeria nautilei inhabits areas with intermediate exposure to vent fluids and biological interactions are likely the most important factor shaping this snail's realized niche. Microhabitats of non-symbiont-containing fauna were defined in terms of symbiont-containing faunal distributions. The crab Austinograea spp. occupies areas with the greatest exposure to vent flow; shrimp, the snail Eosipho desbruyeresi, and anemones inhabit intermediate zones of vent flow; and the squat lobster Munidopsis lauensis dominates the periphery of diffuse flow areas, with little exposure to vent fluids. The physical structure of different lava types along the ELSC differentially affects the diffusion of vent fluids, which has a variety of implications for fauna, particularly distributions of zoanthids, anemones, and mixed communities of I. nautilei and B. brevior.

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…Within a region, individual vent patches rarely host the full species pool . In some regions, neighboring vents may differ strikingly in species composition, as has been observed in the mid-Atlantic (Desbruyères et al, 2001) western Pacific (Podowski et al, 2010;Metaxas, 2011), and Gulf of California (Goffredi et al, 2017). In contrast, in the eastern Pacific, individual vents tend to host a subset of the province's species pool, without geographic clines (Juniper et al, 1990;Van Dover and Hessler, 1990).…”

“…Competitive inhibition, facilitation, and habitat provision or modification influence the abundance of different species during initial colonization but also throughout the development of communities following a disturbance (Sarrazin et al, 1997;Mullineaux et al, 2003;Podowski et al, 2010). For instance, on the East Pacific Rise (EPR), the presence of the small tubeworm Tevnia may facilitate colonization by the giant tubeworm Riftia (Mullineaux et al, 2000) which then appears to be excluded by mussels.…”

Molecular taxonomy and naming of five cryptic species ofAlviniconchasnails (Gastropoda: Abyssochrysoidea) from hydrothermal vents

“…Alviniconcha spp. (Collins, Kennedy, & Van Dover, 2012;Denis et al, 1993;Hashimoto & co-authors, 1999;Henry, Childress, & Figueroa, 2008;Kim & Hammerstrom, 2012;Kyuno et al, 2009;Podowski, Ma, Luther, & Wardrop, 2010;Sen et al, 2013;Van Dover et al, 2001). Alviniconcha aff.…”

Vent Fauna in the Okinawa Trough

“…Other environmental factors, such as salinity, dissolved oxygen (DO), and the concentration of H 2 S, may contribute to the zonation, but there is no supportive evidence for this from the northwestern Pacific. In vent fields in the southwestern Pacific, sulfide concentration and DO, in addition to temperature, appear to contribute to the gradient distribution of vent fauna (Podowski et al 2010). Sediment-Associated Fauna.…”