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

198
Although the standing crop of D.
in Area 5b had
almost increased to its original value in 21 months, the size
structure of the second crop was very different from that of the
first. Whereas 15 large specimens formed over half the wet
of the first crop, i·t took 50 of the
in the second
crop to the sOJiie amouQt. Thus 21 months after • three
times as had to be cut to obtain the wet
of The absence of any large in the second
also meant that the fraction of "'let t in the second
was much than it ha.d been in the first.
36% of all specimens longer than 1 m ... rere fertile,
but in the crop, this percentage had increased to 90%. Wherewere
as
widely distributed over the fronds of most
the , they were to 1 s
behind the frond all plants in the reharvest.
Plants left in this area were half the size of those left in
Area Sb at Tautuku, and reharvesting took place after 15 months
instead of 21 months. The second crop contained very fe\11 fertile
, and to 36% of the first crop. If this area
ha.d been left another 12 months then presumably the second crop
would have we about the same as that obtained I al
it would have still contained no
On the three areas culled in and summer I i.e. after
the fertile I there was no immediate of young
DUY'villaea Instead a of other seaweeds spread over
the rock surface between the holdfasts, and a coral1itl!::'. domina ted
"turf" deve 'l"he holdfasts rotted slowly, and their
posi \>lere still recognisable as bare patches on the rock, nearly
6 months after In I many of these bare si teg 'IIlere
colonised by small D~ antarctica plants, but very fe\