148
R. K. DELL
in this area and were seen in thick mats feeding on the large isopod
Glyptonotus antarcticus.
Dearborn’s thesis (1965) has not been published and we must rely
for short general accounts (1967, 1968) and references to the thesis in
sundry publications by other authors, for any official knowledge of it.
Since this is obviously the most comprehensive study of a relatively
shallow-water high Antarctic habitat, its publication is greatly to be
desired. I n the meantime the general accounts do not give enough
detail to elucidate the assemblages present. Until Dearborn’s work can
be published, and until Bullivant’s (1967) classilication of deeper water
assemblages can be clothed in sufficient identifications to make them
objective, fine detail or broad generalization is all that is really available.
variety of areas in
McMurdo Sound have been able to give some picture of benthic zonation
in this area. Shallow-water habitats down to 33 m or so are dominated
by ice phenomena. Annual sea ice formed to a depth of 4 m or so floats
with the tides and scours subtidal areas. Floes from the ice-shelf can
continue the scouring action rather less drastically down to about 15 m.
Anchor ice forming on the bottom, in sufficient density to form a mat,
lifting all manner of benthic organisms and carrying them to the surface seems to form regularly down to 15 m and has been seen down to
33 m. Such animals as the fish Trematomus, the echinoid Sterechinus
neumayeri, the sea star Odontmter validus, the nemertean Lineus
corrugatus, the isopod Glyptonotus, and several pycnogonids were seen
caught in newly formed ice. These authors have recorded twelve
Sterechinus and forty Odontaster frozen into a square metre of the sea
ice.
Zone 1. Extends down to about 16 m. Ice phenomena seem to clear
most animals from this area every year. Those animals which are
present must re-colonize the area during the annual ice-free period.
Sterechinus, Odontmter, Lineus, Glyptonotus, and a few pycnogonids and
fish forage into the area during the summer. A similar group of animals
with the addition of Neobuccinum eatoni was recorded from this zone
by Pearse and Giese (1966).
Zone 11. Except where anchor ice (for one reason or another) cannot
form this zone extends from 15 m down to a sharply defined 33 m
lower boundary. I n this zone sessile animals are common. The dominant sessile forms are Alcyonium paessleri (alcyonarian), Artemidactirr
victrix, Isotealia antarctica, Urticinopsis antarctica and Hormathia
Dayton et al. (1970) as a result of 178 dives in
This ice action apparently produces a marked zonation.
R. K. DELL
in this area and were seen in thick mats feeding on the large isopod
Glyptonotus antarcticus.
Dearborn’s thesis (1965) has not been published and we must rely
for short general accounts (1967, 1968) and references to the thesis in
sundry publications by other authors, for any official knowledge of it.
Since this is obviously the most comprehensive study of a relatively
shallow-water high Antarctic habitat, its publication is greatly to be
desired. I n the meantime the general accounts do not give enough
detail to elucidate the assemblages present. Until Dearborn’s work can
be published, and until Bullivant’s (1967) classilication of deeper water
assemblages can be clothed in sufficient identifications to make them
objective, fine detail or broad generalization is all that is really available.
variety of areas in
McMurdo Sound have been able to give some picture of benthic zonation
in this area. Shallow-water habitats down to 33 m or so are dominated
by ice phenomena. Annual sea ice formed to a depth of 4 m or so floats
with the tides and scours subtidal areas. Floes from the ice-shelf can
continue the scouring action rather less drastically down to about 15 m.
Anchor ice forming on the bottom, in sufficient density to form a mat,
lifting all manner of benthic organisms and carrying them to the surface seems to form regularly down to 15 m and has been seen down to
33 m. Such animals as the fish Trematomus, the echinoid Sterechinus
neumayeri, the sea star Odontmter validus, the nemertean Lineus
corrugatus, the isopod Glyptonotus, and several pycnogonids were seen
caught in newly formed ice. These authors have recorded twelve
Sterechinus and forty Odontaster frozen into a square metre of the sea
ice.
Zone 1. Extends down to about 16 m. Ice phenomena seem to clear
most animals from this area every year. Those animals which are
present must re-colonize the area during the annual ice-free period.
Sterechinus, Odontmter, Lineus, Glyptonotus, and a few pycnogonids and
fish forage into the area during the summer. A similar group of animals
with the addition of Neobuccinum eatoni was recorded from this zone
by Pearse and Giese (1966).
Zone 11. Except where anchor ice (for one reason or another) cannot
form this zone extends from 15 m down to a sharply defined 33 m
lower boundary. I n this zone sessile animals are common. The dominant sessile forms are Alcyonium paessleri (alcyonarian), Artemidactirr
victrix, Isotealia antarctica, Urticinopsis antarctica and Hormathia
Dayton et al. (1970) as a result of 178 dives in
This ice action apparently produces a marked zonation.