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

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(17) The mean standing crop of D. antarctica per kilometre
of shore, based on transects made throughout New Zealand is 123.5
tonnes/km. Values range from 47 to 190 tonnes/km.
(18) D. antarctica quickly recolonises areas cleared duritl~
the fluiting period. A 1a'Wn-like sward of small plcmts (up to
40 OOO/m2) may cover the entire rock surface. Recolonisa'cion is
much slm1ler on areas cleared outside the fruiting season I particula:cly
those cleared during spring and early summer. This is because
'ehe rock is covered with a varie-ty of other algae in the interim
between the t:ime of clearing, and the next fruiting season.
(19) Ren\Oval of one DuX'villaea species does not alter the range
of a Imler or higher zoned lJuX'viUaea species.
(20) Recolonising D. antarctica grow slowly compared to most
large laminarian algaeo On the southeast Otago coast the fastest
growing specimens elongated 3 m in t\11O years.
(21) Most regrowth on experimentally cleared areas was due to
recolonisa"tion, and not the rapid growth of very small or microscopic
plants that had pregiously lain dormant beneath the thick canopy of
blades.
(22) Recolonising D. antarctica grON faster than small plants
that are suddenly exposed by culling la:rge and medium sized plants.
(23) The upper limit of recolonising D. antarotioa swards on
·the southeast Otago coast is significantly lower than the normal
upper level of the kelp band. At Kaikoura, the upper limit of the
recolonising sward is initially higher than normal, but subsequently
retracts to the upper limit of the adjacent D< antarctica band.
(24) Both D. antaPctica and D. wiZlana are cap~ble of living
up to ten years or longer. Because of the very slow growth of
understorey plants~ size is not necessarily indicative of age.
(25) Growth rate of understorey pla.nts is incr.eased by cu.lling
la.rge and medium specimens. However, after culling, many understorey
plants are swept away because of the sudden increase in ~