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Discovery of 15 new species in marine protected areas in deep offshore seabed
―Ministry of the Environment-commissioned project “Overview of Offshore Seabed Nature Conservation Area Survey”

Press Releaseプレスリリース
2025.04.17
JAMSTEC

1. Key Points

  • A monitoring survey of marine protected areas in the deep offshore seabed was conducted since 2020, when the areas were designated as protected, as part of a project commissioned by the Ministry of the Environment.

  • To date, 15 new species and numerous rare species have been reported in the survey.

  • Within the surveyed area, Japan’s offshore seabed nature conservation areas have been maintained in a healthy state since their designation approximately four years ago, demonstrating the conservation effect of their role as protected areas.

2. Overview

Principal Researcher Yoshihiro Fujiwara and others from the Research Institute for Global Change, JAMSTEC, conducted a large-scale monitoring survey of biodiversity in offshore marine protected areas (Offshore Seabed Nature Conservation Area※) designated in 2020, from which they have reported 15 new species to date (Figure 1, Table 1). The researchers also estimated the age of the giant black coral species that they discovered during the survey. These species may be long-lived organisms with lifespans of over 7,000 years. The team also discovered a new habitat for the Yokozuna Slickhead, which is known as the apex predator in marine areas with depths exceeding 2,000 meters, within the offshore marine protected area. The majority of the offshore marine protected areas that have been surveyed to date have been found to be in a healthy state with minimal human impact. This result has demonstrated the role of the designated areas in the conservation of protected areas. Expectations are high regarding the benefits of collecting such biodiversity information, including that of new species, and clarifying the distribution and ecology of organisms in deep marine areas, including offshore marine protected areas. Such research will promote understanding of vulnerable deep-sea habitats and help us to accurately assess the impact of global environmental change on this ecosystem. This research was the result of the Ministry of the Environment commissioned project “FY2020–FY2025 Offshore Seabed Nature Conservation Area Survey.

Supplemental Information
※

Offshore Seabed Nature Conservation Area
Marine areas in the offshore deep seabed that were designated as protected in December 2020 by the Nature Conservation Act. Four areas were included in the designation, namely the (1) southernmost part of the Japan Trench and area around Izu-Ogasawara Trench, (2) area including the Naka-Mariana Ridge and West Mariana Ridge, (3) area including Nishi-Shichito Ridge, and (4) area in the northern part of the Mariana Trench. This designation resulted in 13.3% of marine areas under Japan’s authority being designated as protected areas, thereby achieving the Aichi Biodiversity Target of conserving at least 10% of marine areas by designating them as protected areas by 2020.

Figure

Figure 1. New species discovered in offshore seabed nature conservation areas
The alphabets in the figure correspond to Table 1.

Table 1．New species discovered in offshore seabed nature conservation areas
No.Species namePhylumSampling areaSampling
location		Sampling
depth (m)
AAnthoptilum gnome Kushida, Kise, Iguchi, Fujiwara & Tsuchida, 2024CnidariaNishi-Shichito RidgeAn’ei Seamount998
bAsthenactis agni Kobayashi, Yamamoto, Fujiwara, Tsuchida & Fujita, 2022EchinodermataNishi-Shichito RidgeAn’ei Seamount1970
CBranchinotogluma nikkoensis Jimi, Chen & Fujiwara, 2022AnnelidaNaka-Mariana Ridge, West Mariana RidgeNikko Seamount458
DDendrogaster nike Jimi, Kobayashi, Moritaki, Woo, Tsuchida & Fujiwara, 2023ArthropodaNishi-Shichito RidgeAn’ei Seamount1970
EEiconaxius kaimei Komai, Tsuchida & Fujiwara, 2024ArthropodaNishi-Shichito RidgeAn’ei Seamount888
FEiconaxius latirostrum Komai, Tsuchida & Fujiwara, 2024ArthropodaNishi-Shichito RidgeShoho Seamount456
GGenrokunemertes obesa Hookabe, Koeda, Fujiwara, Tsuchida & Ueshima, 2022NemerteaNishi-Shichito RidgeGenroku Seamount2084
HGonionida kaimei Komai, Tsuchida & Fujiwara, 2023ArthropodaNishi-Shichito RidgeAn’ei Seamount456.9
ILacydonia shohoensis Hookabe, Jimi, Yokooka, Tsuchida & Fujiwara, 2022AnnelidaNishi-Shichito RidgeShoho Seamount2042
JMelinnopsis shinkaiae Jimi, Hookabe, Woo & Fujiwara, 2025AnnelidaIzu-Ogasawara TrenchDaiichi-Kashima Seamount3623
KPericlimenes variabilis Komai, Tsuchida & Fujiwara 2023ArthropodaNaka-Mariana Ridge, West Mariana RidgeRitto Seamount642–666
LSternostylus spiniger Komai, Tsuchida & Fujiawra, 2023ArthropodaNaka-Mariana Ridge, West Mariana RidgeRitto Seamount657
MTetrastemma shohoense Hookabe, Kohtsuka, Fujiwara, Tsuchida & Ueshima, 2023NemerteaNishi-Shichito RidgeShoho Seamount455
NUroptychus medius Komai, Tsuchida & Fujiawra, 2023ArthropodaNaka-Mariana Ridge, West Mariana RidgeRitto Seamount2001
OVitrumanthus flosculus Kise & Reimer, 2024CnidariaNishi-Shichito RidgeShoho Seamount, An’ei Seamount400

For this study

Yoshihiro Fujiwara, Principal Researcher, Research Institute for Global Change（RIGC）, Marine Biodiversity and Environmental Assessment Research Center (BioEnv), Deep-Sea Biodiversity Research Group (DeepBio), JAMSTEC

For press release

Press Office, Marine Science and Technology Strategy Department, JAMSTEC
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