A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

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at the entran.ce to l-'Iilford Sound are much smo.ller than D. antaY'tytiaa
specimens grO'tlling in a similarly exposed habitat in the outer coast
of Five Fingers Peninsula, Resolution Island, 150 km further south.
Perhaps the most obvious difference between northern alid r;Wutherli
populations of D. antaratica was the absence of cape form populations
in the far south.
Semisheltered inlets and gently sloping shores,
which in the south are dominated by cape form D, antarotiaa, are
usually dominated by species of CarpophyUum and LandsbeY'gia
queY'aifolia in the far nori:b.
plants increases with latitude~
In general. the incidence of ca.pe form
although such popUlations are absent
from most of the west coast of the New Zealand mainland.
Apart from differences in size, there were few morphological
differences between samples of thonged plants. The distal branching
of stipes, described earlier, is largely confined to D. antaratica
plants in the southern half of the South Island and Stewart Island.
1"'he peculiar lateral processes produced by D. antarc;'tioa stipes were
only observed in the Chatham Islands.
A relatively common occurrence
of unusual frond features amongst southern populations is partly
caused by the fact that Her-podisous is largely confined to southern
regions.
Relatively few data from \,lidely separated D. Willana populations
were collected.
Sampling was mainly restricted to the Kaikoura
coast and southeast Otago. The data from these two areas (Table 5.5),
and additional field observations indicate that the mean size of Do
wi llana plants increase southwards. On the basis of visual assessment,
D. wilZana plants on the westland coast at Charleston (41°54'5) and
Twelve Mile Bluff (42°20'S) are smaller than specimens in southern
Fiordland (south of 45°30'8).
On the South Island east coast,
specimens at Parititahi are shorter, and have shorter and thinner
stipes than specimens at Tautuku, 600 kID further south.
Table 5.5 Comparison of D. willana specimens from Tautuku Peninsula
and Parititahi Tunnel. Specimens ~10rter than 1 m excluded from both
samples.
Locality n mean length mean stipe mean stipe
(m) length (em) diam. (rom)
Parititahi 185 1.94 ± 0"08 57.0 ± 2.3 39.4 ± 1.5
Tauttocu 40 flo 79 ± 0.41 80.1 :!: 7.0 62.5 ± 3.3