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

114
'rable 5,3 Measurements of D. antarctica and D. UYillana from top
and bottom of their respective bands on the shore. (a) Second
Slope, Tauttiku Peninsula; (b) near Parititahi. Kaikoura.
(a)
n
Mean stipe
diam. (mm)
Mean stipe
length (em)
Mean stipe
lI)gt (g)
Sample from top of
D. antaPctica belt
37
Sample from bottom 53
of D. antarctica belt
Significance of difference
between means
46.8 ± 5.7 22,5 1: 1.3 481 ± 79
37.1 ± 1.1 31.2 ± L2 339 ± 30
(b)
n
Mean plant Mean stipe Mean stipe Distance
length (m) length diam. (mm) from HFD·
(em)
to lowest
lateral (em)
D. wiZlana at
E.L.W.S.
119 L6l±O.07
33.5 ± .1.4
43.B ± 1.7 25.0 ± L8
D. willa:na at
bottom of subtidal
channels
68 2.53 ± 0 .09
48.8 ± 1.6
80.4 ± 5.6 44.9 ± 5.6
Significance of
difference
between means
t:**
***
D. willana specimens fram the subtida.l. at Partititahi 'runnel,
were compared with specimens growing at the sublittoral fringe in
the same area (Table S.3b). Subtidal plants VJere significantly
longer, and had longer and thicker stipes. Since ,[lost of these
subtidal plants were attached to the bottoms of deep channels (1-2 m
belDl" E. L. W. S.) the ir long stipes can suspend their laminae close
to the surface and prevent them being shaded by plants attached to
the channel sides. A long stipe also means that the laminae are
suspended out in the centre of the channel, rather than close to the
sides.
Why the subtidal D, wi Zlana have th icker stipes than those
growing in mare shalloH water is less obvious. Perhaps it is
because wave action is less severe in deeper water. sO thCl.t the
plants attached to the bottom or channels live longerth.an others