48 
ture of the four groups, but at 326 and 322 
the Subtropical Group is dominant. 
The T-S-P diagram (Fig. 10) illustrates the 
general correlation between the occurrences 
of planktonic groups and the distribution of 
the water properties shown in the geographi- 
cal charts. Station 342 is the only one clearly 
in subantarctic water and its fauna is entirely 
of Subantarctic groups. Station 330 is situated 
in the portion of the T-S-P diagram represent- 
ative of water of subantarctic origin intruding 
into, and mixing with, coastal-subtropical 
waters. The four planktonic groups are pres- 
ent, which is consistent. However, both its 
position in the T-S-P diagram, and the pre- 
dominance of Subantarctic species indicate 
that the subantarctic influence is strongest. 
Station 337 lies just outside the larger of the 
subantarctic intrusions in the T-S-P diagram. 
Isotherms and isohalines (Figs. 19^, 20b) sug- 
gest a strong coastal influence, which is con- 
firmed by the predominance of Coastal spe- 
cies. Stations 326 and 322 are separated from 
all other plankton stations by the subtropical 
convergence. Both occur in water of sub- 
tropical origin, somewhat diluted by lower 
salinity coastal water, and Subtropical species 
predominated in the plankton. 
It is important that the species’ occurrences 
of Series 6 indicate the approximate position 
of the subtropical convergence. A comparison 
of faunal distributions, as well as physical 
data, of Series 5 and 6 show that the conver- 
gence has moved southwards during the three 
months separating the series. 
Series 7. Stations 793 to 921: 13 to 17.XL31 
The stations of this series have enabled the 
source of the Southern Subantarctic species to 
be demonstrated, and have distinguished 
them through their origin in cold water from 
the Northern Subantarctic group. The tem- 
peratures and salinities of the stations are 
within those given for subantarctic water by 
Deacon (1937). Because water samples were 
lost, the salinities of the three plankton sta- 
tions 795, 826, and 921 have been arbitrarily 
PACIFIC SCIENCE, Vol. XIII, January 1959 
chosen from within the range indicated by 
other stations in the series. The north-going 
component in the West Wind Drift, ensures 
that the influence of water in the latitudes of 
Stations 826 and 921 eventually will be felt 
about southern New Zealand. Through its 
agency, the more adaptable of Southern Sub- 
antarctic species will be transported to the 
nearshore waters. The temperature at Station 
795 was 2°C. lower than any from which the 
Northern Subantarctic Group was taken. It 
would appear that this difference may be 
adequate as a barrier to these species in view 
of the geographical proximity of the station 
to Foveaux Strait (Fig. 2). 
DISCUSSION 
The selection of those species which are 
most representative of the faunas of particu- 
lar waters can be made from the species’ dis- 
tributions in relation to temperature and sa- 
linity with the aid of the T-S-P diagrams. 
In turn, the extent of the influence of water 
bodies entering an area can be assessed 
through the distribution of the species in the 
T-S-P diagram, as well as by the temperatures 
and salinities of the waters. Species selected as 
representative of the fauna of one water may 
occur in other waters, often at groups of sta- 
tions for which there are similar properties of 
temperature and salinity. The stations of such 
a group may be widely scattered in time and 
place, but affinity between them is demon- 
strable by means of their species’ content. 
Thus the species relate the waters at the sta- 
tions to their sources, and at the same time 
demonstrate the direction and extent of the 
water movements which have brought about 
the planktonic distribution. Because the spe- 
cies of a group indicate the presence (and 
source) of a water body, therefore the distri- 
bution of this water in another with which it 
is mixing can be traced in the T-S-P diagram 
through the distribution of these species. 
The study raises problems relating to the 
transfer of organisms between one body of 
water (or range of conditions) and another. 
