THE DEEP ATLANTIC OCEAN
133
large macrofauna (1–100 g) to benthic biomass on the
Vøring Plateau. The very large animals in particular
were rarely caught in core samples, but were estimated
to contribute as much as 70% of total macrofaunal
biomass.
Burrowing organisms may play an important role in
geochemical processes and sediment bioturbation on
the Vøring Plateau. Romero-Wetzel (1987) described
a network of very narrow (0.2–0.5 mm diameter),
predominantly vertical burrows which penetrated to a
depth of 50 cm and intersected the sediment surface
as tiny, inconspicuous openings. These are constructed
by the sipunculan Golfingia (Nephasoma) and may be
extremely abundant (up to 20 000 m
−2 ). The sipunculan
draws organic matter down into its burrow and ejects
feces back onto the sediment surface. Elaborate burrow
systems are constructed within the top 10 cm of
sediment by the enteropneust Stereobalanus canadensis
(Romero-Wetzel, 1989). The burrows are 5–6 mm in
diameter, and include vertical shafts to the surface as
well as extensive, dichotomously branched horizontal
galleries. Individual burrow systems may contain
several individuals of S. canadensis as well as masses
of their fecal pellets (Jensen, 1992b). Like its shallowwater relatives, S. canadensis secretes brominated
phenols. These toxins deter colonization of the burrow
wall by metazoan meiofauna, although foraminifers
(mainly Lagena sp.) appear resistant to their effects
(Jensen et al., 1992a). Another large infaunal inhabitant
of the Vøring Plateau (at depths of 1244–2926 m),
the anemone Cerianthus (Anthozoa), occupies a horizontal, branched tube 12–40 cm below the sediment
surface in densities of up to 3.5 individuals m
−2 (Jensen,
1992a). Jensen suggested that the tube systems act as a
‘gas pipeline’ for methane and hydrogen sulfide derived
from deeper in the sediment column. He speculated
that the gases might support endosymbiotic bacteria or
bacteria living in the tube lining.
Jensen et al. (1992b) discovered distinct difference
between the meio- and macrofauna on opposite sides
on a ridge on the Vøring Plateau. The side exposed
to sediment advection (Expo-stations) had generally
higher oxygen consumption rates, lower meiofaunal
biomass and lower maximum depth of penetration of
meiofauna than the other side where sediment was
being accumulated (Impo-stations). Taxa which were
more abundant at the Impo-stations included larger
nematodes (e.g., Pararaeolaimus rumohri and various
desmoscolecids) and several pogonophore species (i.e.
infaunal worms); those found mainly at the Expostations included smaller nematodes (Acantholaimus
elegans, Desmodora pilosa, Rhabdodemania sp. and
Sabatieria sp.), sipunculans, sponges and hydroids (i.e.
suspension and deposit-feeders). Jensen et al. (1992b)
concluded that a distinctive pogonophore and nematode
fauna occupies areas of the Vøring Plateau which
experience high levels of sediment and organic-carbon
accumulation.
Foraminifera are an important component of the
Norwegian–Greenland Sea benthos. On the Vøring
Plateau, Romero-Wetzel and Gerlach (1991) estimated that they constituted 41.6% of the biomass of
‘larger meiofauna’ (wet weight 1–100 micrograms),
in addition to an unknown proportion of the ‘small
meiofauna’. Thies (1991) described ‘live’ (Rose Bengal
stained) and dead foraminiferal faunas (>250 mm
fraction) in 81 box cores from areas between Greenland
and Spitzbergen (Svalbard) and between Greenland
and Norway (depth range 81 to 3695 m). A total of
102 species were recognized, but the faunas were of
low diversity, particularly in the deep basins where
only 3–5 species were present in the >250 mm fraction.
Thies (1991) recognized a low-diversity fauna on
the lower slope and in the basins, dominated by
Cibicidoides wuellerstorfi, Cribrostomoides subglobosa, Crithionina hispida and Pyrgo rotaliaria. This
contrasts with a more diverse fauna (up to 19 species)
on the upper slope and shelf characterized by Cibicides
lobatulus, Cribrostomoides subglobosa, Reophax difflugiformis and R. scorpiurus She concluded that food
supply exerted a decisive influence on the foraminiferal
faunas. This is in accordance with the observations
of Heeger (1990; reviewed by Gooday et al., 1992)
that many of the Foraminifera in the Norwegian–
Greenland Sea feed on fresh phytodetritus. Moreover,
ingested food can be converted into biomass very
rapidly (Heeger, 1990), within a period of days in
experimental systems (Altenbach, 1992; Linke et al.,
1995). Some species (C. subglobosa, Pyrgo murrhina, Rhabdammina abyssorum), show corresponding
physiological adaptations to a fluctuating food supply.
Rapidly fluctuating ATP content and heat production
indicate that they can survive periods of starvation by
metabolizing their own protoplasm, while the ability
to phosphorylate adenosine monophosphate (AMP) to
adenosine triphosphate (ATP) allows a rapid physiological reawakening to occur when the Foraminifera are
presented with a sudden food pulse (Linke, 1992; Linke
et al., 1995).
133
large macrofauna (1–100 g) to benthic biomass on the
Vøring Plateau. The very large animals in particular
were rarely caught in core samples, but were estimated
to contribute as much as 70% of total macrofaunal
biomass.
Burrowing organisms may play an important role in
geochemical processes and sediment bioturbation on
the Vøring Plateau. Romero-Wetzel (1987) described
a network of very narrow (0.2–0.5 mm diameter),
predominantly vertical burrows which penetrated to a
depth of 50 cm and intersected the sediment surface
as tiny, inconspicuous openings. These are constructed
by the sipunculan Golfingia (Nephasoma) and may be
extremely abundant (up to 20 000 m
−2 ). The sipunculan
draws organic matter down into its burrow and ejects
feces back onto the sediment surface. Elaborate burrow
systems are constructed within the top 10 cm of
sediment by the enteropneust Stereobalanus canadensis
(Romero-Wetzel, 1989). The burrows are 5–6 mm in
diameter, and include vertical shafts to the surface as
well as extensive, dichotomously branched horizontal
galleries. Individual burrow systems may contain
several individuals of S. canadensis as well as masses
of their fecal pellets (Jensen, 1992b). Like its shallowwater relatives, S. canadensis secretes brominated
phenols. These toxins deter colonization of the burrow
wall by metazoan meiofauna, although foraminifers
(mainly Lagena sp.) appear resistant to their effects
(Jensen et al., 1992a). Another large infaunal inhabitant
of the Vøring Plateau (at depths of 1244–2926 m),
the anemone Cerianthus (Anthozoa), occupies a horizontal, branched tube 12–40 cm below the sediment
surface in densities of up to 3.5 individuals m
−2 (Jensen,
1992a). Jensen suggested that the tube systems act as a
‘gas pipeline’ for methane and hydrogen sulfide derived
from deeper in the sediment column. He speculated
that the gases might support endosymbiotic bacteria or
bacteria living in the tube lining.
Jensen et al. (1992b) discovered distinct difference
between the meio- and macrofauna on opposite sides
on a ridge on the Vøring Plateau. The side exposed
to sediment advection (Expo-stations) had generally
higher oxygen consumption rates, lower meiofaunal
biomass and lower maximum depth of penetration of
meiofauna than the other side where sediment was
being accumulated (Impo-stations). Taxa which were
more abundant at the Impo-stations included larger
nematodes (e.g., Pararaeolaimus rumohri and various
desmoscolecids) and several pogonophore species (i.e.
infaunal worms); those found mainly at the Expostations included smaller nematodes (Acantholaimus
elegans, Desmodora pilosa, Rhabdodemania sp. and
Sabatieria sp.), sipunculans, sponges and hydroids (i.e.
suspension and deposit-feeders). Jensen et al. (1992b)
concluded that a distinctive pogonophore and nematode
fauna occupies areas of the Vøring Plateau which
experience high levels of sediment and organic-carbon
accumulation.
Foraminifera are an important component of the
Norwegian–Greenland Sea benthos. On the Vøring
Plateau, Romero-Wetzel and Gerlach (1991) estimated that they constituted 41.6% of the biomass of
‘larger meiofauna’ (wet weight 1–100 micrograms),
in addition to an unknown proportion of the ‘small
meiofauna’. Thies (1991) described ‘live’ (Rose Bengal
stained) and dead foraminiferal faunas (>250 mm
fraction) in 81 box cores from areas between Greenland
and Spitzbergen (Svalbard) and between Greenland
and Norway (depth range 81 to 3695 m). A total of
102 species were recognized, but the faunas were of
low diversity, particularly in the deep basins where
only 3–5 species were present in the >250 mm fraction.
Thies (1991) recognized a low-diversity fauna on
the lower slope and in the basins, dominated by
Cibicidoides wuellerstorfi, Cribrostomoides subglobosa, Crithionina hispida and Pyrgo rotaliaria. This
contrasts with a more diverse fauna (up to 19 species)
on the upper slope and shelf characterized by Cibicides
lobatulus, Cribrostomoides subglobosa, Reophax difflugiformis and R. scorpiurus She concluded that food
supply exerted a decisive influence on the foraminiferal
faunas. This is in accordance with the observations
of Heeger (1990; reviewed by Gooday et al., 1992)
that many of the Foraminifera in the Norwegian–
Greenland Sea feed on fresh phytodetritus. Moreover,
ingested food can be converted into biomass very
rapidly (Heeger, 1990), within a period of days in
experimental systems (Altenbach, 1992; Linke et al.,
1995). Some species (C. subglobosa, Pyrgo murrhina, Rhabdammina abyssorum), show corresponding
physiological adaptations to a fluctuating food supply.
Rapidly fluctuating ATP content and heat production
indicate that they can survive periods of starvation by
metabolizing their own protoplasm, while the ability
to phosphorylate adenosine monophosphate (AMP) to
adenosine triphosphate (ATP) allows a rapid physiological reawakening to occur when the Foraminifera are
presented with a sudden food pulse (Linke, 1992; Linke
et al., 1995).