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

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growth in the length for the entire sample also over 26 months was
considerably higher (350 ± 19.3%). The grollJth rat.e of small plants
at Ohau (curve "A", :Pig. 7.5) was apprmdmn_te1y twice that of small
D. antarctica plants at Tautuku.
Stipe diameter of marked D. antarctica plants at Ta.utulm
increased from 27.7 ± 1.6 to 41.8 ± 1.4 rom in 26 months (a mean perccntage
increase of 125.0 ± 22.1%). The percentage :tncrease 'VIas much
greatex at Ohau Point where mean diameter increased from 1200 ± 0.13 rom
to 29.1 ± C.S'rom (311 ± 25.2~) in 26 months.
Relative increments in stipe diameter and total length were
inversely proportional to the overall size of the plant (Figs 705; 7.6; 7.8'
The total length of Ohau Point specimens in the following size classes:
0.5-100 In, 1-2 m, 2-4 m and 4+ m, increased respectively 195%,95%,
-5% and -5% in approximately three years. Total length of many
large specimens at both localities declined over the measuring periodo
There was a distinct seasonal pattern in lIlean growth rate at
Tautuku, with an increase during spring and sunmer, and a decline in
thE:! late autuilln and win tar (Figs" 7. 7; 7. B) • A similar but less
marked seasonal pattern occurred at Ohau Point (Fig. 7.9). The
percentage of D. anta~ctica plants in the Tautuku sample that decreased
in length between one Census and the next was higher during the
winter'than during the summer (Fig. 7.10).
Growth measurements for D. antarctica plants in the more
sheltered localities at Kean Point and Oaro are tabulated below, and
are compared ~.,i th data from Ohau Point (Table 7.3)_ In general,
Oaro and Kean Point plants grew more slowly than those at Ohau Point.
In contrast to the seasonal pattern of growth described for plants
at Tautukn and Ohau, Oaro specimens greH more slowly during the ~"inter
of 1973, than during the spring and early SUlnmer period which followed
(Table 7.4),
'l'able 7,3 Percentage increase in total length of D. antarctica at
three localities. June 1973 - January 1974.
Size class (111) Oaro Kean Pt. Ohan
0 - 0.5 46.8 ± 19 118 ± 23.5 co. 137
0.5 ~ 1 49.9 ± 16.7 60"1 ± 25,8 77
1 - 2 47 A ± 9,3 -3.3 ± 13.3 61
~
2 10.3 40