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

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6" 4 ENVIRONMENTAL FACTORS POSSIBLY INFLUENCING THE LIBERA'l'ION OF
G~TES
Plants collected during \oJinter released copious quantities of
gametes soon after they had been dragged ashore, In less an
hotlY I
the male plant.s had exuded a \oJhitish mucous layer conto.ining
millions of sperm.
Small mounds of ova accumulated around the
ostioles on the surface of female laminae. and these mi~ed with
mucus to form a dark green slime.
Gamete release was only infrequently
observed in rJ1e field mainly because constant. t'letting of the fronds
prevented the accumulation of ova.
On exceptionally calm days small
mounds of ova were occasionally observed on D. anta~atiaa
had been continuously exposed to air for 30 minutes or moreo
laminae that
toJere released irrespective of the sta'c:e of the tide or t:he time of
the month when the samples or whole plants ... tere collected.
L~ina
samples collected in winter and brought back to the
laboratory usually released gametes \men placed in seawater.
Gametes
Some
samples released spontaneously, and the ripest specimens frequently
released in plastic bags en route to the laboratory"
Others
released after several hours. San~les were capable of producing
gamet.es more or less continuously for 24 hours, and occasionally longer.
These rather general observations suggested that Durvillaea plants
might release gcnTletes continuously over the \o,inter months.
However,
it was considered possible that certain environmental factors might
exert. some influence on their liberation.
Some rather simple
experlinents were therefore set up to investigate any effect t~at
water temperature, wave action and exposure might: have on the release
of gametes. For convenience j these were referred to a.s the
"temperature", "agitation", and "exposure" experiments.
A description
of the methods employed for each is provided in ChartEr 2, while the
results are given here.
(a)
Samples from ten. D. antOX'ctiaG and ten D. willana plants ~Iere
left to release in seawater at 5°, 11° and 20°C"
Results are tabulated below (Tables 6.3 and 6.4). Release \\Yas
heaviest at 11°C, which ~