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

2.2
ANJ\ LY~ I ~;
4
(a)
Samples used for population analyses are listed in Appendix S.
Unless otherwise stated, all plants, including those just visible
to the naked eye, were collected. In most cases the samples came
from a known area of shore and extended across the depth of the kelp
bond. Samples were effectively belt. h::ansects I the width of: IrJhich
depended on the accessibility of the area, shore slope and sea
conditions duriHgthe sampling period.
Measurements of individual plants included total length, stipe
length, stipe din.meter' (a t the base of the stipe), holdfast diameter
(for specimens with 50litaxy holdfasts), maximum lamina ·thickness,
total weight (!,,'et) and stipe weight (Fig. 2.4). Subjective measurements
included the degree of division of laminae, the degree of
honeycombing (taking into account both thickness and the expanse
honeycombed) , the area of lamina covered with t.onceptacles and the
extent of burrowing' in the holdfast. 'l'here were seven ascending
catego:cies: nil, low, I oVI/medium, medium, medium/high, high and
V0Dj high.
Subsamples were selected by laying all specimens out in rows
on a beach or rock platform and :candomly selecting plants, having
previously prepared a list of random numbers cr:canged in ascending
order.
Seasonal changes in population structure were monitored at
Tautuku because all samples were exposed to similar cortcli lions"
To reduce as fa.r as possible any influence of sea,son, specimens
shorter than 1 m we.t"e excluded from analyses when comparing samples
from ~'lidely
sepay'ated arEas.
(b)
A fragIllent of lamina of each fertile plant was collected in all
samples. These were preserved in 10% seawater formalin and later
examined in the laboratory to assess their reproductive state.
Samples of the blade \