THE PERIPHERAL DEEP SEAS
283
deep water outside the influence of hydrothermal brines
tends to be of low biomass and diversity, owing to the
low surface primary productivity and vertical flux to
the seabed (Karbe, 1987; Thiel et al., 1987).
The only classic expedition to the deep Red Sea
was that of the Austrian vessel Pola between 1895 and
1898. Only certain groups of organisms were described,
including the Crustacea (Balss, 1915; Michaelson,
1918, 1921) and corals (von Marenzeller, 1907), whilst
a general account of the fauna was given by Fuchs
(1901). Modern investigations have included Russian
studies (Murina, 1971; Monin et al., 1980, 1982);
the Saudi–Sudan Red Sea Joint Commission examined
the deep-water fauna as a prelude to assessing the
possibilities of extracting metal-rich muds from the
deeps (Karbe et al., 1981).
Thiel (1987) has produced the most recent review
of the fauna of the deep Red Sea. Most major groups
are present, at least in low numbers, but there are no
records of phoronids, pogonophorans, hemichordates or
crinoids. This may be a result of inadequate sampling,
as there are no physiological or ecological aspects
that would preclude these groups. The deep-water
fauna is, not surprisingly, closely related to the deepwater fauna of the Indian Ocean, though the sill at
Bab al Mandab limits gene flow between the deepwater populations on either side. The most significant
aspect Thiel noted was the rarity of a ‘true’ benthic
deep-sea fauna in the Red Sea. Invasion of the deep
waters by shallow-water fauna may be facilitated by
the relatively homogeneous warm upper water column.
Shallow-water species that are found at depth include
the stomatopod Kempina zanzibarica (Manning, 1981)
and the fish Iago omanenesis, Lophiodes mutilus,
and Muraensox cinereus (Klausewitz, 1981, 1983;
Klausewitz and Thiel, 1982).
Amongst endemic deep-sea species are the prawns
Haliporus steindachneri and Parapandalus adensameri, the amphipods Glycerina teretis, Pseudamaryllis nonconstricta and Socarnes allectus (Andres, 1981)
and the anemone Halcurias sudanensis (RiemannZ¨ urneck, 1983). The meiofauna of the deep Red Sea
(507 to 1977 m) is dominated by nematodes, followed
by harpacticoid copepods and polychaetes (Thiel,
1979). Generally meiofaunal abundance decreased with
depth, with the exception of the deepest station. Thiel
(1979) explained this higher density as being due
to downslope transport of organic matter past the
steeply sloping station at 1549 m, which had the lowest
meiofaunal abundance.
On a more local scale, Por and Lerner-Seggev (1966)
described the zonation of fauna in the Gulf of Eilat. The
two deepest zones they described were a Palaeostoma–
Hyalinoecia community (from 360 to 500 m depth) and
the pteropod ooze community from 500 m to ~1500 m.
Of true bathyal species, these authors recorded the
bivalve Amussium siebenrocki, the gastropod Murex
tribulus and the decapod crustacean Achaeus erythraeus. Below 500 m the fauna is depauperate, but
nematodes, polychaetes, aplacophorans and gammarid
amphipods are found in low numbers. Por and LernerSeggev (1966) suggested that this fauna would be
typical of the bathyal deep sea not affected by brines.
Caribbean Sea
The most detailed analysis of the deep-water biota
of the Caribbean is the study of three stations in
the Venezuela Basin described in detail in Marine
Geology (1985). The three stations consisted of one
on the western flank of the Aves Ridge dominated
by hemipelagic sediments, a station dominated by
turbidites in the deepest part of the basin, and a site
covered by calcareous pelagic ooze in the western part
of the basin (see Fig. 9.4).
The biomass and community structure of the microbiota were determined by analysis of ester-linked
phospholipids from sediments at each of the three
stations (Baird and White, 1985). Because of the
complexity of organic molecules the biomass was
measured as picomoles of the phospholipid palmitic
acid (16:0) g
−1 (dry weight). The 16:0 denotes methyl
branching, 10 carbon atoms from the carboxyl end
of the molecule. No significant difference was found
between stations, the biomass ranging from 94 to 343
picomoles 16:0 g
−1 . These values are some 20% of
those at the North Atlantic HEBBLE site (Baird and
White, 1985), and 3% of those in an estuary. From
these data the calculated bacterial abundance in the
surficial sediments of the Venezuela Basin was between
0.75×10
8 and 1.73×10
8 cells g
−1 (Baird and White,
1985). Procaryotic organisms dominated the microbial
community, and the fatty acids observed were believed
to be indicative of aerobes.
In contrast to the microbiota, the meiofauna showed
significant differences between the two station (Tietjen,
1984; Woods and Tietjen, 1985). In the hemipelagic
sediments the density was 13.19±1.43 S.E. individuals cm
−2 compared to the pelagic sediments
(8.12±0.95 S.E. individuals cm
−2 ) and lowest in the
283
deep water outside the influence of hydrothermal brines
tends to be of low biomass and diversity, owing to the
low surface primary productivity and vertical flux to
the seabed (Karbe, 1987; Thiel et al., 1987).
The only classic expedition to the deep Red Sea
was that of the Austrian vessel Pola between 1895 and
1898. Only certain groups of organisms were described,
including the Crustacea (Balss, 1915; Michaelson,
1918, 1921) and corals (von Marenzeller, 1907), whilst
a general account of the fauna was given by Fuchs
(1901). Modern investigations have included Russian
studies (Murina, 1971; Monin et al., 1980, 1982);
the Saudi–Sudan Red Sea Joint Commission examined
the deep-water fauna as a prelude to assessing the
possibilities of extracting metal-rich muds from the
deeps (Karbe et al., 1981).
Thiel (1987) has produced the most recent review
of the fauna of the deep Red Sea. Most major groups
are present, at least in low numbers, but there are no
records of phoronids, pogonophorans, hemichordates or
crinoids. This may be a result of inadequate sampling,
as there are no physiological or ecological aspects
that would preclude these groups. The deep-water
fauna is, not surprisingly, closely related to the deepwater fauna of the Indian Ocean, though the sill at
Bab al Mandab limits gene flow between the deepwater populations on either side. The most significant
aspect Thiel noted was the rarity of a ‘true’ benthic
deep-sea fauna in the Red Sea. Invasion of the deep
waters by shallow-water fauna may be facilitated by
the relatively homogeneous warm upper water column.
Shallow-water species that are found at depth include
the stomatopod Kempina zanzibarica (Manning, 1981)
and the fish Iago omanenesis, Lophiodes mutilus,
and Muraensox cinereus (Klausewitz, 1981, 1983;
Klausewitz and Thiel, 1982).
Amongst endemic deep-sea species are the prawns
Haliporus steindachneri and Parapandalus adensameri, the amphipods Glycerina teretis, Pseudamaryllis nonconstricta and Socarnes allectus (Andres, 1981)
and the anemone Halcurias sudanensis (RiemannZ¨ urneck, 1983). The meiofauna of the deep Red Sea
(507 to 1977 m) is dominated by nematodes, followed
by harpacticoid copepods and polychaetes (Thiel,
1979). Generally meiofaunal abundance decreased with
depth, with the exception of the deepest station. Thiel
(1979) explained this higher density as being due
to downslope transport of organic matter past the
steeply sloping station at 1549 m, which had the lowest
meiofaunal abundance.
On a more local scale, Por and Lerner-Seggev (1966)
described the zonation of fauna in the Gulf of Eilat. The
two deepest zones they described were a Palaeostoma–
Hyalinoecia community (from 360 to 500 m depth) and
the pteropod ooze community from 500 m to ~1500 m.
Of true bathyal species, these authors recorded the
bivalve Amussium siebenrocki, the gastropod Murex
tribulus and the decapod crustacean Achaeus erythraeus. Below 500 m the fauna is depauperate, but
nematodes, polychaetes, aplacophorans and gammarid
amphipods are found in low numbers. Por and LernerSeggev (1966) suggested that this fauna would be
typical of the bathyal deep sea not affected by brines.
Caribbean Sea
The most detailed analysis of the deep-water biota
of the Caribbean is the study of three stations in
the Venezuela Basin described in detail in Marine
Geology (1985). The three stations consisted of one
on the western flank of the Aves Ridge dominated
by hemipelagic sediments, a station dominated by
turbidites in the deepest part of the basin, and a site
covered by calcareous pelagic ooze in the western part
of the basin (see Fig. 9.4).
The biomass and community structure of the microbiota were determined by analysis of ester-linked
phospholipids from sediments at each of the three
stations (Baird and White, 1985). Because of the
complexity of organic molecules the biomass was
measured as picomoles of the phospholipid palmitic
acid (16:0) g
−1 (dry weight). The 16:0 denotes methyl
branching, 10 carbon atoms from the carboxyl end
of the molecule. No significant difference was found
between stations, the biomass ranging from 94 to 343
picomoles 16:0 g
−1 . These values are some 20% of
those at the North Atlantic HEBBLE site (Baird and
White, 1985), and 3% of those in an estuary. From
these data the calculated bacterial abundance in the
surficial sediments of the Venezuela Basin was between
0.75×10
8 and 1.73×10
8 cells g
−1 (Baird and White,
1985). Procaryotic organisms dominated the microbial
community, and the fatty acids observed were believed
to be indicative of aerobes.
In contrast to the microbiota, the meiofauna showed
significant differences between the two station (Tietjen,
1984; Woods and Tietjen, 1985). In the hemipelagic
sediments the density was 13.19±1.43 S.E. individuals cm
−2 compared to the pelagic sediments
(8.12±0.95 S.E. individuals cm
−2 ) and lowest in the