THE PERIPHERAL DEEP SEAS
287
biomass with depth. Zenkevitch (1963) recorded only
five macrofaunal species from below 3000 m and
only 25 species between 2000 and 3000 m (Terazaki,
1999). Down to 2000 m the fauna is dominated by
the echinoderms, Ctenodiscus crispatus, Luidiaster
tuberculatus and Thaumatometra tenuis, the cnidarians
Caryophyllia clavus, Lafoeina maxima and Primnoa
resdaeformis pacifica, and the polychaetes Harmothoe
impar, Jasmineria pacifica and Nephthys longisetosa,
as well as decapods and molluscs, particularly the Buccinidae. Nishimura (1966) referred to this community
as the ‘taraba community III’. He believed that the
‘taraba community III’ extended from about 300 m
to 1500 m, below which the community petered out.
Below 2000 m the qualitatively and quantitatively poor
fauna included a variety of polychaetes, the brittle star
Ophiura leptoctenia, and the molluscs Axinus sp. and
Pecten randolfi, as well as a number of peracarid crustaceans (Zenkevitch, 1963). The main characteristic of
this faunal group is its apparent evolutionary youth
since, owing to the young geological age of the Sea
of Japan, it has not had time to acquire an endemic
character of its own. Zenkevitch (1963) considered
the polychaetes Harmothoe derjugini and Tharyx
pacifica, the echinoderm Pedicellaster orientalis and
the decapod Chionoecetes angulatus bathyalis as the
only true endemic forms in the Sea of Japan. Nishimura
(1966) was more conservative, suggesting that only
the deep-sea polychaete H. derjugini is truly endemic.
All other species found in the deep waters of the
Sea of Japan are eurybathyic forms also found in the
cold waters of the Pacific and Bering Sea. A number
of boreal forms have also invaded the Sea of Japan.
Vinogradov (cited in Zenkevitch, 1963) identified the
low temperature and salinity of the Sea of Japan rather
than its recent history as causes of the low diversity.
Nishimura referred to the deep fauna as a pseudoabyssal fauna and supported Vinogradov in suggesting
that the unique cold temperatures and high salinity
account for the penetration and success of a coldadapted secondary deep-sea fauna, and the failures of
archaic deep-sea faunas to colonize the deep waters,
especially after periods of anoxia (Terazaki, 1999).
The deep-water fish of the Sea of Japan are also
characteristically cold-water species from the families
Cottidae, Liparidae, Lumpenidae, Pleuronectidae and
Zoarcidae (Nishimura, 1968, 1983). Some 20 species
have been recognized (Zenkevitch, 1963); Nishimura
(1968) listed 8 deep-water zoarcids, 12 deep-water
cottids and 16 deepwater species of Liparidae. The
poverty of invertebrate species is reflected in the lack
of diversity of the fish fauna. Of particular interest
to Nishimura (1968) was the poverty of macrourids
in the Sea of Japan compared to deep waters on
the Pacific side of Japan. Approximately 50 species
of macrourids are known from off southern Japan in
deep water, whereas in the Sea of Japan there were
only one or two species, about which there was some
taxonomic uncertainty. The same feature is seen in the
Myctophidae where some 33 species are seen on the
Pacific side of Japan and only two within the Sea of
Japan (Nishimura, 1968). These two species were also
believed to be recruited by larval transport from the
East China Sea.
Sea of Okhotsk
Benthic biomass in the Sea of Okhotsk is patchy.
The biomass and species composition is particularly
affected by the low oxygen concentration. Zenkevitch
(1963) identified two zones of deep-sea benthic fauna
in the Kurile Basin. The deepest part of the basin is
dominated by a zone of bottom feeders including the
polychaete families Capitellidae and Maldanidae, the
holothurian family Molpadidae, the echinoid Brisaster
and the asteroid Ctenodiscus. Mean biomass in this
zone is ~102 g m
−2 . The main part of the Kurile
Basin is dominated by immobile filter feeders including the pennatulids Pavonaria and Umbellula,
crinoids, the ascidian Culeolus, sabellid worms and
the pogonophoran Lamellisabella zachsi. In this zone
the biomass is at its lowest at ~30.5 g m
−2 . The low
benthic biomass may be related to the particularly
low surface primary production in the central part of
the Sea of Okhotsk. Much of this fauna has close
links with those at similar depths in the Pacific.
A particular feature, noted by Zenkevitch (1963) is the
high incidence of gigantism amongst deep fauna in the
Sea of Okhotsk, the barnacle Balanus evermanni, the
holothurian Psychropotes raripes and the polychaete
Potamilla symbiotica all displaying gigantism.
The benthic foraminiferal communities of the Sea of
Okhotsk have been described in detail (Saidova, 1997).
In the Kurile deeps these communities are dominated
by Globobulimina auriculata, Trochammina abyssorum
living in the deepest parts on sediments with an organic
content reaching 2%, and Bolivina pseudodecussata,
Elphidium batialis and Miliolinella recenta living at
depth, but on sediments with <1.5% organic carbon.
287
biomass with depth. Zenkevitch (1963) recorded only
five macrofaunal species from below 3000 m and
only 25 species between 2000 and 3000 m (Terazaki,
1999). Down to 2000 m the fauna is dominated by
the echinoderms, Ctenodiscus crispatus, Luidiaster
tuberculatus and Thaumatometra tenuis, the cnidarians
Caryophyllia clavus, Lafoeina maxima and Primnoa
resdaeformis pacifica, and the polychaetes Harmothoe
impar, Jasmineria pacifica and Nephthys longisetosa,
as well as decapods and molluscs, particularly the Buccinidae. Nishimura (1966) referred to this community
as the ‘taraba community III’. He believed that the
‘taraba community III’ extended from about 300 m
to 1500 m, below which the community petered out.
Below 2000 m the qualitatively and quantitatively poor
fauna included a variety of polychaetes, the brittle star
Ophiura leptoctenia, and the molluscs Axinus sp. and
Pecten randolfi, as well as a number of peracarid crustaceans (Zenkevitch, 1963). The main characteristic of
this faunal group is its apparent evolutionary youth
since, owing to the young geological age of the Sea
of Japan, it has not had time to acquire an endemic
character of its own. Zenkevitch (1963) considered
the polychaetes Harmothoe derjugini and Tharyx
pacifica, the echinoderm Pedicellaster orientalis and
the decapod Chionoecetes angulatus bathyalis as the
only true endemic forms in the Sea of Japan. Nishimura
(1966) was more conservative, suggesting that only
the deep-sea polychaete H. derjugini is truly endemic.
All other species found in the deep waters of the
Sea of Japan are eurybathyic forms also found in the
cold waters of the Pacific and Bering Sea. A number
of boreal forms have also invaded the Sea of Japan.
Vinogradov (cited in Zenkevitch, 1963) identified the
low temperature and salinity of the Sea of Japan rather
than its recent history as causes of the low diversity.
Nishimura referred to the deep fauna as a pseudoabyssal fauna and supported Vinogradov in suggesting
that the unique cold temperatures and high salinity
account for the penetration and success of a coldadapted secondary deep-sea fauna, and the failures of
archaic deep-sea faunas to colonize the deep waters,
especially after periods of anoxia (Terazaki, 1999).
The deep-water fish of the Sea of Japan are also
characteristically cold-water species from the families
Cottidae, Liparidae, Lumpenidae, Pleuronectidae and
Zoarcidae (Nishimura, 1968, 1983). Some 20 species
have been recognized (Zenkevitch, 1963); Nishimura
(1968) listed 8 deep-water zoarcids, 12 deep-water
cottids and 16 deepwater species of Liparidae. The
poverty of invertebrate species is reflected in the lack
of diversity of the fish fauna. Of particular interest
to Nishimura (1968) was the poverty of macrourids
in the Sea of Japan compared to deep waters on
the Pacific side of Japan. Approximately 50 species
of macrourids are known from off southern Japan in
deep water, whereas in the Sea of Japan there were
only one or two species, about which there was some
taxonomic uncertainty. The same feature is seen in the
Myctophidae where some 33 species are seen on the
Pacific side of Japan and only two within the Sea of
Japan (Nishimura, 1968). These two species were also
believed to be recruited by larval transport from the
East China Sea.
Sea of Okhotsk
Benthic biomass in the Sea of Okhotsk is patchy.
The biomass and species composition is particularly
affected by the low oxygen concentration. Zenkevitch
(1963) identified two zones of deep-sea benthic fauna
in the Kurile Basin. The deepest part of the basin is
dominated by a zone of bottom feeders including the
polychaete families Capitellidae and Maldanidae, the
holothurian family Molpadidae, the echinoid Brisaster
and the asteroid Ctenodiscus. Mean biomass in this
zone is ~102 g m
−2 . The main part of the Kurile
Basin is dominated by immobile filter feeders including the pennatulids Pavonaria and Umbellula,
crinoids, the ascidian Culeolus, sabellid worms and
the pogonophoran Lamellisabella zachsi. In this zone
the biomass is at its lowest at ~30.5 g m
−2 . The low
benthic biomass may be related to the particularly
low surface primary production in the central part of
the Sea of Okhotsk. Much of this fauna has close
links with those at similar depths in the Pacific.
A particular feature, noted by Zenkevitch (1963) is the
high incidence of gigantism amongst deep fauna in the
Sea of Okhotsk, the barnacle Balanus evermanni, the
holothurian Psychropotes raripes and the polychaete
Potamilla symbiotica all displaying gigantism.
The benthic foraminiferal communities of the Sea of
Okhotsk have been described in detail (Saidova, 1997).
In the Kurile deeps these communities are dominated
by Globobulimina auriculata, Trochammina abyssorum
living in the deepest parts on sediments with an organic
content reaching 2%, and Bolivina pseudodecussata,
Elphidium batialis and Miliolinella recenta living at
depth, but on sediments with <1.5% organic carbon.