26 
PACIFIC SCIENCE, VoL XIII, January 1959 
penetrating down the east coast — an exten- 
sion of the East Cape Current (see Garner 
1954 , also his fig. 4^). That the data are in 
fact attributable to crossing the convergence 
is borne out to a considerable degree by the 
biological evidence. 
Coastal water appears from Figure 3 to be 
an admixture of fresh water runoff and water 
of subtropical and subantarctic origins. Sub- 
antarctic water is of lower salinity than the 
water of subtropical origin and will dilute it; 
both of these waters and their mixtures will be 
diluted by fresh water. The salinity of coastal 
waters ranged from less than 34 °/oo (not 
shown in Fig. 3) up to about 35 Voo, and de- 
pends in part on which oceanic water pre- 
dominates at a station, and on the proportion 
of fresh water in the coastal water mixture. 
The temperature ranged between 13° and 
16°C., which is intermediate between those of 
waters of subtropical and subantarctic origins. 
In the T-S diagram (Fig. 3) the water en- 
velopes have been drawn arbitrarily to include 
all points entered. Solid lines indicate those 
water masses identifiable from the present 
data; dashed lines are indicative of dilution 
of the waters from these masses. The double 
dashed line signifies the subtropical conver- 
gence and separates all stations occupied to 
the south of it from those to the north. The 
proper extent of the convergence cannot be 
shown because the low winter temperatures 
of the water of subtropical origin permit the 
coolest samples from this water to be located 
in the summer temperature range of the 
coastal-subtropical mixture. Because of this, 
and because no stations crossed the conver- 
gence clear of the influence of coastal water, 
no position for the subtropical convergence 
between uncontaminated waters is shown in 
the diagram. 
From the distribution of properties in the 
T-S diagram and from its form, general move- 
ments of both subtropical and subantarctic 
waters towards coastal water can be deduced. 
There will be mixing between these (and with 
fresh water) and this is represented in the 
region of extreme salinity variation in the 
temperature range of about 13° to 15.5°C. 
Confirmatory evidence on water movements 
and especially those concerning mixing areas 
is to be derived from the distribution and 
interrelationships of the several groups of 
indicator species. In Figure 3, the stippled 
arrows show the general water movements as 
deduced from the T-S diagram, while in 
Figure 10 the movements as demonstrated by 
the planktonic distribution are illustrated. 
There is a general similarity. 
species’ groups in relation to 
WATERS IN THE AREA 
Four groups of species have been selected 
as representative of the zooplankton resident 
in the waters of the area of sampling (Tables 
3, 4). There is one group from each of the 
coastal and subtropical waters, and two from 
water originating in the subantarctic. One of 
the subantarctic groups represents those spe- 
cies occurring predominantly in the colder 
waters and for convenience called the "South- 
ern” Subantarctic Group; the other has been 
selected from those species occurring in water 
of subantarctic origin which has been warmed 
in its progress northward, namely, the "North- 
ern” Subantarctic Group (see pp. 31-33). 
The species and the species’ groups are 
listed in Table 4, together with the numbers 
of specimens captured and the stations at 
which they were taken. 
The degree to which the association of 
species in each of the groups is maintained in 
their normal environment, and when they are 
carried into abnormal conditions, is sum- 
marised in Figures 5 to 9 and is discussed 
below. 
Southern Subantarctic Group 
Stations 795, 826, and 921 (Fig. 2) lie 
within the field of cold subantarctic water as 
defined earlier, and appear to be removed 
from the influence of water of subtropical 
