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

'I'he reproductive period of D. willana was very similar to that
of D. antarctica except that. the onset and 'cermination of gamete
release was about one month lat.er (Fig. 6.2).
At Kaikoura, for
example, approximately 6% of the D. antarctica contained conceptJere still
releasing (Fig. 6.2). This slight difference betl\Teen the reproductive
periods of the bqo species was also borne out by the observation that
in September 1973 and 1975, it \"as far easier to find D. lI>iZlarta plants
which would relea.se in the laboratory I than it was to find D.
antarctica plants.
Spot samples have shown that the peak release period for D.'
anta:t'ctica at Woodpecker Bay, Bethels 'Beach and the Chatham Islands is
probably also in midwinter. There is some evidence that the northern
D. antarctica populations have a more contracted releasing period.
Samples from Bethels Beach and Piha collected in early May 1974,
contained very few cleaved oogonia, and there was certainly no sign
of any release. All were rated "c" (Table 6.2). Kaikoura and
Tautuku samples collected in the same week were much more advanced.
8-15% of the samples were cla.ssed as "D". In August 1975 nearly 90%
of all the Auckland samples were rated "E", whereas over half the
Kaikoura specimens were still releasing and were thus in the "c"
category.
Table 6.2
Analyses of frond samples from piha and Bethels,
Date Stages of conceptacle development n
A 13 C D E
28 September 1973 0 a 0 17 IS (32)
6 r·iay 1974 0 0 15 0 0 (15 )
22 May 1974 a 0 29 2 0 (30)
25 June 1975 0 a 1 12 0 (13)
16 Sept.e!i1.ber 1975 0 0 0 2 16 (113)