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Offshore Seafloor 321 Naisei-shoto Islands, Okinawa Trough

Basic Information A separate window opensReferences

Area (km2) 180769
Maximum water depth (m) 4424

Reason(s) for selection A separate window opensCriteria

Selected due to high levels for criteria 1, 4, 5, 6, and 8, and selected by MARXAN software.

Characteristics A separate window opensReferences

These waters make up part of the Nansei-shoto Islands and Okinawa Trough.
The Okinawa Trough is a back arc basin in which large cracks have been forming since roughly two million years ago as the continental crust splits. Hydrothermal vent communities have been found from the Minami-Ensei Knoll (150 km west of Amami-Ohshima) in the north to the Hatoma Knoll (northwest of Miyako Island) and Yonaguni Knoll No. 4 (northwest of Yonaguni Island) an others in the south, making it one of the big hydrothermal vent fields in the western Pacific (Fujikura et al., 2008). Megabenthos numbering 49 species have been confirmed at the Minami-Ensei Knoll, a large-scale hydrothermal area bristling with chimneys. Bathymodiolus, Paralomis jamsteci, Shinkaia crosnieri, and other species live around the chimneys. The hydrothermal vent area at Hatoma Knoll includes a chimney of hydrothermal solution more than 300°C in temperature, Shinkaia crosnieri, Alvinocaris longirostris, and Lepetodrilus nux. At Yonaguni Knoll No. 4 is a black smoker that emits pitch-black hydrothermal solution, and its biota resembles that of Hatoma Knoll. Numerous other hydrothermal vent communities have been confirmed in these waters as well (Fujikura et al, 2008).
In addition, distribution of precious coral has been confirmed in Hozan-sone area between Okinawa and Miyako Islands (Nonaka and Muzik, 2009; Suzuki, 1991).

Environment / Habitat information A separate window opensData source

Okinawa Trough, Chemosynthetic community, Seamount, Canyon

Species information (*) A separate window opensData source

Criteria 1
Galeus longirostris (Longnose Sawtail Catshark)
Holanthias flagris
Bassozetus zenkevitchi
<Bivalva, Gastropoda>
Conus boeticus
Corallium sulcatum
Echinogorgia asper
Euplexaura abietina
Melithaea flabellifera
Paratelesto rosea
Criteria 4
Centrophorus squamosus (Leafscale Gulper Shark)
Acalycigorgia ceylonensis
Acanthogorgia dofleini
Annella mollis
Annella ornata
Annella reticulata
Anthogorgia bocki
Anthogorgia glomerata
Astrogorgia rubra
Bebryce boninensis
Bebryce indica
Carijoa riisei
Corallium sulcatum
Echinogorgia asper
Echinogorgia spinosa
Ellisella andamanensis
Ellisella plexauroides
Euplexaura abietina
Euplexaura anastomosans
Euplexaura crassa
Euplexaura flava
Euplexaura rhipidalis
Euplexaura robusta
Isis hippuris
Junceella fragilis
Junceella fragiris
Junceella juncea
Melithaea flabellifera
Melithaea ocracea
Menella praelonga
Menella spinifera
Muricella complanata
Paratelesto rosea
Pseudobebryce acanthoides
Rumphella aggregata
Sinularia gravis
Sinularia numerosa
Stereotelesto rubra
Subergorgi verriculata
Subergorgia appressa
Subergorgia mollis
Subergorgia pulchra
Subergorgia reticulata
Subergorgia suberosa
Subergorgia verriculata

* This is the species list of which meet the criteria. In that matter, this list does not include all species that inhabit the individual area.


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