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

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Evidence of frond damage caused by the parasitic alga
HeY'podiscus durvilleae. by herbivores or by wave force' was noted.
Lamina samples were also collected to determine the sex of the plants.
When plants were swept alt)ay it was noted whethe'C the stipe had b;~oken
or pulled out of the holdfast, or if the holdfast had been detached.
(c)
Detailed {nvestigation of reproductive periodicity was made by
collecting lamina samples of 40 marked D. antaJ~ctica and 40 marked D.
1ui l lana at different seasons ove r three years. In the [irst year
samples were collected at appX"oximately monthly intervals (Kaikoura)
and bimonthly int:ervals (Tautuku). Samples were collected less
regula:cly in the second and third years. Lamina sa.roples of unmarked D.
an taY'ctica were also collected at Bethells Bea.ch at different seasons.
An 18 mm diameter cork borer was used to punch out a sample of
the lamina at a posi tion about hal£v..lay along its 1 eng th. These
discs were preserved .immediately in 10% seawater formalin and later
examined microscopically in the laboratory.
2.4
(a)
Nine areas of D. anta:t'ctica llashing
back and forth over the rocle surface and possibly dislodging a.ny
recolonising plants. Regrowth was monitored by way of permanent
line transects and by photographing four permanent quadrats (with
sides 0.3 ru) in each area.
The