152
Lisa A. LEVIN and Andrew J. GOODAY
attracted to bait include opportunistic generalist feeders
as well as the more specialized scavengers (Thurston,
1979; Thurston et al., 1994). However, in the case of
both amphipods and fish, the scavengers which are
abundant around bait represent only a small proportion
of the species known to be present in the deep sea
(Thurston, 1979, 1990; Merrett and Haedrich, 1997).
Although still limited, information on the taxonomic
composition, distribution and ecology of Atlantic
necrophage faunas is growing. Many species are widely
distributed in the Northeast and Tropical Atlantic.
According to Thurston (1990), the region between 8ºN
and 50ºN supports a ‘single faunal entity’. Most of
the amphipods caught and photographed on the Iberian
Abyssal Plain (4885 m) by a baited fish trap equipped
with a camera belonged to the genera Orchomene
and Paralicella. The photographic record revealed a
slow increase in numbers of amphipods present on the
bait, and subsequent fluctuations in abundance which
may have been related to the presence of fish in the
trap and to current activity. These interactions were
examined further by Lampitt et al. (1983), who used
methods similar to those of Thurston (1979) at a site
4009 m deep close to the mouth of the Porcupine
Seabight. Fluctuations in the numbers of amphipods
visible on the bait could be related to tidal cycles and to
the presence of small black fish (probably Paraliparis
bathybius). Amphipods were most abundant when
current velocities were low. However, appearances of
the black fish coincided with the flood tide (i.e., higher
current velocities) and also with a marked decline in
numbers of visible amphipods, suggesting that the fish
preyed on the amphipods.
In situ studies of feeding and digestion by Eurythenes gryllus, conducted on the Nares Abyssal Plain
(3421 m) using time-lapse photography, revealed rapid
consumption of bait (1.8 g individual
−1 h
−1 ) by large
amphipods (3–6 cm). These crustaceans ingested 30–
60% of their body weight within 12 h (Hargrave, 1985).
From studies on the Nares and Sohm Abyssal Plains
using traps which allowed timed exposure to bait, it
was established that, once E. gryllus starts to feed on
carrion, digestion is rapid, with 0.4–1.0% of the gut
contents lost per hour and 95% digested in 1–10 days
(Hargrave et al., 1995). Eurythenes has mandibles
and a gut adapted to rapid gluttonous feeding; it
apparently can survive long periods between meals.
Other lysianassid scavengers (e.g., Orchomene) have
smaller guts and seem to process food in a more
continuous manner (Sainte-Marie, 1992). Sainte-Marie
(1992) suggested that none of the deep scavenging
amphipods are completely obligate necrophages, and
that foraging in the water column is required to
compensate for scarce resources (see also Thurston,
1990).
Photographic records obtained on the Porcupine
and Madeira Abyssal Plains using a baited timelapse camera system (BATHYSNACK) revealed that
decapods are also common scavengers in the deep
Atlantic (Thurston et al., 1994). On the Porcupine
Abyssal Plain, the dominant necrophages identifiable
in photographs were fish, mainly Coryphaenoides
(Nematonurus) armatus and Pachycara bulbiceps, and
the decapod Munidopsis spp. Another decapod, the
shrimp Plesiopenaeus armatus, dominated necrophages
photographed on the Madeira and Cape Verde Abyssal
Plains but was very rarely photographed at bait on
the Porcupine Abyssal Plain, despite being present
in trawl samples taken at this site. These latitudinal
differences between necrophages on Northeast Atlantic
abyssal plains are striking, and possibly linked to
differences in food availability. The greater abundance
of scavenging fish on the Porcupine Abyssal Plain
than on the Madeira or and Cape Verde Abyssal
Plains may reflect higher densities of large animals
present in the pelagic community, and hence of
carrion on the seafloor, on the Porcupine Abyssal Plain
(Merrett, 1987). Plesiopenaeus armatus appears to
be a facultative necrophage which is deterred from
scavenging on the Porcupine Abyssal Plain by the
presence of large fish, but is able to do so at the
southern sites where fish are scarcer (Thurston et al.,
1994). A species of Plesiopenaeus was also attracted,
together with macrourid and ophidiid fish, to a baited
camera system deployed at 4850m on the Demerara
Abyssal Plain (Rowe et al., 1986).
As part of the BIOGAS program, Desbruy` eres et al.
(1985b) studied necrophages with baited traps along
a bathymetric transect between 200 m and 4700 m
across the continental margin in the northern Bay of
Biscay. They also deployed baited cameras 7 m, 100 m
and 200 m above the seafloor at three stations deeper
than 4000 m. Necrophages caught in the traps were
dominated by reptant decapods (Geryon, Munida) and
isopods (Gnathiidae) between 200m and 1800 m and
by fish and amphipods below this depth. Fish were
not observed at all above 1800 m. Among the fish,
sharks were the main group attracted to bait on the
Meriadzek Terrace (1800–3000 m) and the Le Danois
Bank (1980 m), while rattails (macrourids) dominated
Lisa A. LEVIN and Andrew J. GOODAY
attracted to bait include opportunistic generalist feeders
as well as the more specialized scavengers (Thurston,
1979; Thurston et al., 1994). However, in the case of
both amphipods and fish, the scavengers which are
abundant around bait represent only a small proportion
of the species known to be present in the deep sea
(Thurston, 1979, 1990; Merrett and Haedrich, 1997).
Although still limited, information on the taxonomic
composition, distribution and ecology of Atlantic
necrophage faunas is growing. Many species are widely
distributed in the Northeast and Tropical Atlantic.
According to Thurston (1990), the region between 8ºN
and 50ºN supports a ‘single faunal entity’. Most of
the amphipods caught and photographed on the Iberian
Abyssal Plain (4885 m) by a baited fish trap equipped
with a camera belonged to the genera Orchomene
and Paralicella. The photographic record revealed a
slow increase in numbers of amphipods present on the
bait, and subsequent fluctuations in abundance which
may have been related to the presence of fish in the
trap and to current activity. These interactions were
examined further by Lampitt et al. (1983), who used
methods similar to those of Thurston (1979) at a site
4009 m deep close to the mouth of the Porcupine
Seabight. Fluctuations in the numbers of amphipods
visible on the bait could be related to tidal cycles and to
the presence of small black fish (probably Paraliparis
bathybius). Amphipods were most abundant when
current velocities were low. However, appearances of
the black fish coincided with the flood tide (i.e., higher
current velocities) and also with a marked decline in
numbers of visible amphipods, suggesting that the fish
preyed on the amphipods.
In situ studies of feeding and digestion by Eurythenes gryllus, conducted on the Nares Abyssal Plain
(3421 m) using time-lapse photography, revealed rapid
consumption of bait (1.8 g individual
−1 h
−1 ) by large
amphipods (3–6 cm). These crustaceans ingested 30–
60% of their body weight within 12 h (Hargrave, 1985).
From studies on the Nares and Sohm Abyssal Plains
using traps which allowed timed exposure to bait, it
was established that, once E. gryllus starts to feed on
carrion, digestion is rapid, with 0.4–1.0% of the gut
contents lost per hour and 95% digested in 1–10 days
(Hargrave et al., 1995). Eurythenes has mandibles
and a gut adapted to rapid gluttonous feeding; it
apparently can survive long periods between meals.
Other lysianassid scavengers (e.g., Orchomene) have
smaller guts and seem to process food in a more
continuous manner (Sainte-Marie, 1992). Sainte-Marie
(1992) suggested that none of the deep scavenging
amphipods are completely obligate necrophages, and
that foraging in the water column is required to
compensate for scarce resources (see also Thurston,
1990).
Photographic records obtained on the Porcupine
and Madeira Abyssal Plains using a baited timelapse camera system (BATHYSNACK) revealed that
decapods are also common scavengers in the deep
Atlantic (Thurston et al., 1994). On the Porcupine
Abyssal Plain, the dominant necrophages identifiable
in photographs were fish, mainly Coryphaenoides
(Nematonurus) armatus and Pachycara bulbiceps, and
the decapod Munidopsis spp. Another decapod, the
shrimp Plesiopenaeus armatus, dominated necrophages
photographed on the Madeira and Cape Verde Abyssal
Plains but was very rarely photographed at bait on
the Porcupine Abyssal Plain, despite being present
in trawl samples taken at this site. These latitudinal
differences between necrophages on Northeast Atlantic
abyssal plains are striking, and possibly linked to
differences in food availability. The greater abundance
of scavenging fish on the Porcupine Abyssal Plain
than on the Madeira or and Cape Verde Abyssal
Plains may reflect higher densities of large animals
present in the pelagic community, and hence of
carrion on the seafloor, on the Porcupine Abyssal Plain
(Merrett, 1987). Plesiopenaeus armatus appears to
be a facultative necrophage which is deterred from
scavenging on the Porcupine Abyssal Plain by the
presence of large fish, but is able to do so at the
southern sites where fish are scarcer (Thurston et al.,
1994). A species of Plesiopenaeus was also attracted,
together with macrourid and ophidiid fish, to a baited
camera system deployed at 4850m on the Demerara
Abyssal Plain (Rowe et al., 1986).
As part of the BIOGAS program, Desbruy` eres et al.
(1985b) studied necrophages with baited traps along
a bathymetric transect between 200 m and 4700 m
across the continental margin in the northern Bay of
Biscay. They also deployed baited cameras 7 m, 100 m
and 200 m above the seafloor at three stations deeper
than 4000 m. Necrophages caught in the traps were
dominated by reptant decapods (Geryon, Munida) and
isopods (Gnathiidae) between 200m and 1800 m and
by fish and amphipods below this depth. Fish were
not observed at all above 1800 m. Among the fish,
sharks were the main group attracted to bait on the
Meriadzek Terrace (1800–3000 m) and the Le Danois
Bank (1980 m), while rattails (macrourids) dominated