Zooplankton — Bary 
31 
origin. Species taken at these stations may be 
regarded as resident in such subantarctic wa- 
ter. Accordingly the species of the Southern 
Subantarctic Group have been selected from 
those collected at these stations. 
Nine species have been selected. Erythrocy- 
pris sp .5 Clausocalanus laticeps Farran, and 
Sagitta gazellae Ritter-Zahony were present in 
small numbers, Eucalaniis acus Farran in mod- 
erate numbers, and Calanus simillimus Gies- 
brecht was often very common, preponder- 
antly as a Stage V copepodite. Clausocalanus 
laticeps and E. acus are both described as 
typically cold-water species (Farran, 1929; 
Hardy and Gunther, 1935) and stocks of 5. 
gazellae are demonstrated as residing in ant- 
arctic and subantarctic waters by David 
(1955). Calanus simillimus is only to be cap- 
tured from the southern waters (Vervoort, 
1951). The numbers of these five species were 
noticeably reduced in coastal and mixed wa- 
ters, which possibly indicates a lack of adapta- 
bility to the changed conditions. Conse- 
quently they have been distinguished as "In- 
tolerant” species (Fig. 5). Parathemisto (Eu- 
themisto) gaudichaudii (Guer.) and Thysanoessa 
gregaria Sars occurred commonly, but Cyl- 
lopus macropis (Bovallius) and C. magellanicus 
Dana were present in smaller numbers. Thysa- 
noessa gregaria was discussed on page 17. 
P. gaudichaudii is a fairly widespread species 
in the colder waters of northern and southern 
hemispheres, while Cyllopus spp. have been 
recorded only from the colder southern waters 
(Stebbing, 1888; Barnard, 1930; Hurley, 1955; 
Hardy and Gunther, 1935). Larger numbers 
of these species penetrate into coastal waters, 
which suggests a greater tolerance towards 
altered conditions than was apparent among 
the "Intolerant” species; they are accordingly 
distinguished as "Tolerant” species (Fig. 6). 
Both "Tolerant” and "Intolerant” species 
belong in the Southern Group. 
In the T-S-P diagrams Southern Subant- 
arctic species are in continuous distribution, 
in moderate to high numbers, throughout 
water of subantarctic origin. All of the species 
occur as well in coastal water, but the num- 
bers of specimens collected decrease with 
modification of the environmental conditions 
as mixing progresses between the subantarctic 
and coastal waters. This is especially so of the 
"Intolerant” species. Dilution by fresh water 
(Stations 99, 90, 48, 109) and, to a lesser 
degree, increase in salinity (Stations 126, 103, 
124) appear to restrict the "lateral” spread of 
species in the diagrams although much of 
their apparent effects may be due to the sta- 
tions having been occupied in daylight. Ris- 
ing temperatures are less restrictive. Most of 
the species were taken throughout the range 
sampled, but much less commonly at the 
higher temperatures, even in hauls made at 
night. 
Transfers of species from subantarctic to 
coastal waters were largely concentrated about 
three groups of stations, namely 292, 330, 
310, 304, 79, 40, and 189, 190, 125. Subant- 
arctic species also extend, in small numbers, 
through Stations 218, 4, 198, 208, to 178, 138, 
and 130. The stations of these three aggrega- 
tions will be referred to subsequently when 
it will be found that they were situated in 
mixing waters (see Figs. 3, 10). 
Northern Subantarctic Group 
The species selected for the Northern Sub- 
antarctic Group were confined to that warmer 
water (i.e., 11°C. and higher) which is be- 
lieved to have originated in the higher lati- 
tudes of the subantarctic. None was present 
in the colder waters at Stations 795, 826 , or 
921 (Fig. 2). Three species have been selected, 
namely, Sagitta serratodentata Krohn var. tas- 
manica J. M. Thomson, Paracalanus parvus 
(Claus), and Euphausia lucens Hansen. 
Sagitta serratodentata has been described as 
"cold tolerant,” while the variety tasmanica is 
reported to inhabit waters of 11° to 17°C. 
(Thomson, 1947). John (1936) describes E. 
lucens as predominantly a northern subantarc- 
tic species occurring most frequently between 
12° and 14°C., which confirms Tattersall’s 
