5:15 PM - 6:30 PM
[MIS21-P04] Community composition and connectivity of hot vent endemic animals on the Izu-Bonin-Mariana Arc
Keywords:Faunal composition, Gene flow, Mining impact
Lush biological communities associated with deep-sea hydrothermal vents are sustained by high primary production through chemosynthesis. These communities are island-like, being discretely distributed on the normal deep-sea floor lacking in primary production. Nevertheless, planktonic larval dispersal among vents means the compositions of benthos inhabiting vent fields — even those hundreds of kilometres away — are often similar. The 2800 km long Izu-Bonin-Mariana (IBM) Arc is a submarine volcanic arc located off Japan to Guam, and host a number of vent communities. Here, we present the similarity of community composition of these vent communities, and the genetic connectivity among local populations of the vent crab Gandulfus yunohana on the IBM Arc as a case study to identify dispersal barriers and source-sink relationships of the deep-sea vent sites and animal populations.
Our similarity analyses using presence/absence data of 41 taxa in 10 deep-sea vent communities on the IBM Arc showed that the communities are subdivided into three major groups; Izu, Shallow (< 1000m) Bonin-Mariana, and Deep (> 1000m) Bonin-Mariana. This pattern of subdivision indicates that both water depth and tectonic discontinuity contribute to the realized distribution of deep-sea vent animals on the IBM Arc. Genetic analyses of G. yunohana in the vent communities on Myojin Knoll, Bayonaise Knoll (Izu Arc) and Nikko Seamount (Mariana Arc) suggest the populations on the Izu Arc are the source for those on the Mariana Arc. Although this vent crab is distributed continuously on the IBM Arc, its uneven dispersal is indicative of geographic restrictions to larval dispersal. Vents located on the northern part of the IBM Arc, within the Japanese EEZ, are known to produce ore-quality sulfide deposits and are being eyed as targets or deep-sea mining. Knowledge on the dispersal and settlement dynamics of vent endemic animals, like those presented herein, are required for an accurate evaluation of the ecosystems’ resilience for the disturbance that is key to sustainable exploitation.
Our similarity analyses using presence/absence data of 41 taxa in 10 deep-sea vent communities on the IBM Arc showed that the communities are subdivided into three major groups; Izu, Shallow (< 1000m) Bonin-Mariana, and Deep (> 1000m) Bonin-Mariana. This pattern of subdivision indicates that both water depth and tectonic discontinuity contribute to the realized distribution of deep-sea vent animals on the IBM Arc. Genetic analyses of G. yunohana in the vent communities on Myojin Knoll, Bayonaise Knoll (Izu Arc) and Nikko Seamount (Mariana Arc) suggest the populations on the Izu Arc are the source for those on the Mariana Arc. Although this vent crab is distributed continuously on the IBM Arc, its uneven dispersal is indicative of geographic restrictions to larval dispersal. Vents located on the northern part of the IBM Arc, within the Japanese EEZ, are known to produce ore-quality sulfide deposits and are being eyed as targets or deep-sea mining. Knowledge on the dispersal and settlement dynamics of vent endemic animals, like those presented herein, are required for an accurate evaluation of the ecosystems’ resilience for the disturbance that is key to sustainable exploitation.