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

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holes of Oaro spec imens after B month s were 6,. 5 x 3.9; 15.6 x 8,0;
arid 21.8 1C B.9 em respectively. Holes were commonly oval or flask'"
shaped, \·,ith the longest axis parallel t.o the midline of the lamina
or lobe. The most distal holes t"ere much more elongated thar!
closer to the stipe (Fig. 7.4).
(ii)
HoleB punched in line horizontally across the lamina:
In most cases the laminae ripped 0.101')9 the line of holes. 'fhe
l~ninae of only three out of ten Oaro plants remained intact. After
8-9 months there was no decrease in the nurriber of holes, but the distance
between them, and their size had increased considerably. Most were
oval or flask shaped. Originally the holes had been in a straight
line at right angles to the stipe, but after several months they
were found at different heights on the lamina. In two Oaro specimens,
holes near the midline were the largest and most elongated and had moved
higher up the lamina than holes closer to the lamina margin. Tissue
near the midline of the lamina may elongate at a faster rate than tissue
closer to the margin.
(iii) Holes punched ar'ounil the perimeter' of the Zarflina:
These holes also elongated parallel to the midline of the lamina
or lamina lobe. Those at the distal end were more widely spaced
than those at the base. Growth between a pair of holes on one edge
of a lamina or lamina lobe was not alvlays the same as between a pair
of holes directly opposite on the other edge; i.e. left and right
margins can apparently grow at different rates.
Predictably, since the samples comprised a wid!, range of sizes
and ages, growth rates were highly variable. Thus despite the large
sizes of samples. the standard errors of mean mea.surements of frond
length or stipe diameter Nere large. Often, and for no obvious
explanation, except genetic variation, there was a marked difference
between the grmJth rates of seemingly identical specimens attached to
the same composite holdfas t.
At ')~autuku,
mean increment in total plant' length over 26 months
(October 1972 to December 1974) \llaS 60.3 ± 20.0%\)ith individual
me.asurements ranging from minus 95.2% for a 4.5 111 specimen I to plus
735% for a specimen first measured at 0.11 TO" At Ohau Point mean
1
± standard error of the mean.