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Coastal Area 12103 Adjacent waters of Isumi River mouth

Basic Information A separate window opensReferences

Relevant municipalities Isumi, Ichinomiya, Chiba Prefecture
Area (km2) 20

Reason(s) for selection A separate window opensCriteria

Selected by experts as highly unique tidal mud flats with high levels of diversity of species

Characteristics A separate window opensReferences

These are the waters in the vicinity of the Isumi River's mouth. Like the Ichinomiya River's river-mouth tidal mud flats, the area around the mouth of the Isumi River is home to some of the few tidal mud flats including salt-water marshlands between Kujukuri Beach and Sotobo and serves as an important settlement ground on the Pacific coast of the Kanto Region for creatures that live in tidal mud flats. Species that have been confirmed here include Clithon retropictus, Assiminia japonica, Nuttallia olivacea, Sesarmops intermedium, Cerithidea rhizophorarum, Helicana japonica, Clithon retropictus, Angustassiminea castanea, Assiminea parasitologica, Assiminea hiradoensis, Asian clam, Arthritica reikoae, Tylorrhynchus heterochaetus, Laonome albicingillum, red claws crab, Helice tridens, Acmaeopleura toriumii, Macrophthalmus japonicus, Ilyoplax pusilla, and Masago goby (Ministry of the Environment Biodiversity Center, 2013b), and the Sotobo area retains highly unique and diverse tidal mud flats (Yuzuhara, Taru, personal communication).

Environment / Habitat infromation A separate window opensData source

Tidal mud flats (km2) 0.1
Moba (seaweed bed) (km2) 0.2
Coral reef coverage (km2)
Natural coast (km) 2.4
Rate of natural coast (%) 15.8
Sand bank / submerged sand bank
Other habitats

Species information (*) A separate window opensData source

Criteria 1
<Bivalva, Gastropoda>
Angustassiminea castanea
Corbicula japonica
Criteria 2
Neophocaena phocaenoides (Fineless porpoise)
Monticola solitarius (Blue Rock-thrush)[Br/Ne]
Charadrius alexandrinus (Kentish Plover)[Br/Ne]
Laemonema longipes (Threadfin hakeling)[Sp]
Watasenia scintillans (Firefly squid )
Loligo bleekeri (Spear squid)
Criteria 3
Chiromantes haematocheir
Ilyoplax pusilla
Macrophthalmus japonicus
Criteria 7
Macrophthalmus abbreviatus
Macrophthalmus japonicus
<Bivalva, Gastropoda>
Corbicula japonica
<Vascular Plants>
Aster tripolium (Sea aster)

* 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.
Abbreviation in the information is as follows.
[Br/Ne] : Adjacent water of breeding area or nesting site
[Sp] : spawning area
[Ad] : species not used for analysis but add to the list because inhabit information was collected later
[Ex] : species used for analysis but considered to be possibly extinct in the EBSA region (area)
No mark : data of species distribution


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