MOE home > Nature and Parks > EBSA home > Offshore Seafloor > 313 Nankai Trough from Suruga bay to Kyushu waters
Area (km2) | 105431 |
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Maximum water depth (m) | 4907 |
Selected due to high levels for criteria 1, 4, 5, 6, and 8, and selected by MARXAN software.
These waters extend from the east side of Suruga Bay to the Nankai Trough, which drops sharply from the coast all the way to southern Kyushu. Waters that deepen suddenly extend from the coast of Cape Omaezaki to the Kii Peninsula (to the south of Cape Ashizuri), reaching a difference in elevation of 1800 m and a total length of 670 km (Tokuyama et al, 2001). It includes many submarine short canyons (Japan Coast Guard, Hydrographic and Oceanographic Department, 1985).
The V-shaped submarine canyon with depths of 2000 m that runs through the middle of Suruga Bay (the Suruga Trough) separates the Eurasia Plate to the north from the Philippine Sea Plate to the south. On the east side of these waters is a bank called Senoumi where Calyptogena kawamurai have been discovered, suggesting the presence of a community of chemotrophs (Fujikura et al, 2008).
As a boundary between plates, the Nankai Trough is predicted to be the epicenter of a massive earthquake. These waters have been confirmed to be home to the greatest number of seep communities, and here from Kinsunose (off Cape Omaezaki to the south) to the waters 4800 m deep offshore from the coast of Cape Muroto, seep communities have been discovered in numbers unrivaled worldwide. Also here are highly diverse species of bivalves in the family Vesicomyidae, with at least 12 species discovered thus far. At Kinshunose, Mesolinga soliditesta, Bathymodiolus aduloides, and others have been discovered, leading to speculation that there are active methane seeps here. The presence of a bottom simulating reflector (BSR) has been confirmed in this area as well, and it is thought that there is a methane hydrate layer here (Fujikura et al., 2008).
In the Tenryu Canyon that cuts across the Nankai Trough, diverse species have been reported, including not only those specific to seep communities but also many species that depend on photosynthesis, and invasive species as well. The Kumano Basin in the southern Kumano Sea is home to seven mud volcanoes. BSRs have been confirmed in the seabottom called Kumano Knolls Nos. 1-7 as well, and these waters are habitat for Calyptogena fausta, Vesicomya crenulomarginata, Calyptogena (Archivesica) similaris, and others. Seep communities are found at Muroto Knoll off Cape Muroto as well, and Vesicomya kaikoae are distributed here. Species of tubeworm have been confirmed at Ashizuri Knoll of Cape Ashizuri (Fujikura et al, 2008).
Numerous species of precious corals are distributed offshore from Cape Ashizuri and Cape Muroto (Iwasaki, 2008), making this a coral fishing grounds. The waters of the Kumano Sea and off the shore of Tosa are high in biodiversity in terms of fish species as well (Kimura, personal communication).
Chemosynthetic community, Seamount, Canyon
Criteria 1 |
<Pisces> |
Scymnodon ichiharai (Japanese Velvet Dogfish) |
Lycodes caudimaculatus |
Paraliparis atramentatus |
Oxynotus japonicus (Japanese Roughshark) |
Melanostigma orientale |
Zesticelus bathybius |
Pseudonezumia cetonuropsis |
Careproctus rhodomelas |
Bassozetus zenkevitchi |
Trigonognathus kabeyai (Viper Dogfish) |
<Octocorallia> |
Acabaria modesta |
Anthomastus japonicus |
Eunicella pendula |
Melithaea flabellifera |
Minabea ozakii |
Paragorgia regalis |
Pennatula brevipenna |
Pennatula inermis |
Pennatula naresi |
Plumarella flabellata |
Plumarella lata |
Thouarella recta |
Villogorgia japonica |
<Other invertebrate> |
Phoxichilidium ungellatum |
Synhalcurias elegans |
Pycnogonum tenue |
Criteria 4 |
<Pisces> |
Centrophorus squamosus (Leafscale Gulper Shark) |
<Octocorallia> |
Acabaria modesta |
Acabaria ramurosa |
Acalycigorgia densiflora |
Acalycigorgia inermis |
Acalycigorgia irregularis |
Acalycigorgia radians |
Acanella sibogae |
Acanthogorgia multispina |
Acanthoprimnoa cristata |
Anthogorgia bocki |
Anthomastus granulosus |
Anthomastus japonicus |
Anthomuricea brunnea |
Anthoptilum murrayi |
Arthrogorgia ijimai |
Calcigorgia beringi |
Calicogorgia granulosa |
Chromonephthea serratospiculata |
Chrysogorgia lata |
Corallium japonica |
Echinogorgia regularis |
Echinogorgia ridleyi |
Ellisella plexauroides |
Ellisella rubra |
Eunicella pendula |
Euplexaura anastomosans |
Euplexaura curvata |
Helicoptilum rigidum |
Heterogorgia papillosa |
Junceella juncea |
Kophobelemnon hispidum |
Melithaea flabellifera |
Menella lenzii |
Menella praelonga |
Menella spinifera |
Minabea ozakii |
Nidalia rigida |
Paragorgia regalis |
Pennatula brevipenna |
Pennatula fimbriata |
Pennatula inermis |
Pennatula naresi |
Pennatula sanguinea |
Plumarella flabellata |
Plumarella lata |
Radicipes pleurocristatus |
Sarcophyton acutangulum |
Siphonogorgia splendens |
Solenocaulon chinense |
Subergorgia thomsoni |
Telesto aurantiaca |
Thouarella alternata |
Thouarella hilgendorfi |
Thouarella recta |
Trichoptilum spinosum |
Umbellula eloisa |
Umbellula magniflora |
Verrucella miniacea |
Verrucella umbella |
Verrucella umbraculum |
Villogorgia japonica |
* 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.