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

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The series of low ridges absorbs much of the force of waves, and
there is a wide spending area inshore of the DurlJi llaea beds.
Wave
force was rated as sernisheltered (Fig. 4.1f).
(8) Maroa
Two samples were collected near Akaroaj
one at Gateway Point
below the light near the entrance to the harbour (43°53'30"S, 172°59'10"E)
and the other at Wainui 8 kID inside the harbour on the west side
(45°49'50"S, 172°54'25"E).
The kelp band at Gateway Point is on the
steep edge of a narrow tide platform which is fully exposed to southerly
storms. Wave force is very strong. Wainui is sernisheltered by
comparison. Barnacles and limpets dominate the shore above the D.
antarctica band in both areas.
(9) Tautuku Peninsula (46"36'25"5, 169"26'20"E)
The transect on East Rocks (Area 6) was exposed to rough seas
from the northeast.
The East Rocks consist of a series of ledges,
and during strong easterly or southeasterly storms waves are funnelled
along these ledges, thereby approaching Area 6 from above.
The slope
of Area 6 is 11° and both the D. antarctica and D. ~llana bands are
several metres wide (Fig. 2.38).
All other belt transects were on First Slope (8-12°) where there
is full exposure to swells from the east, southeast and south.
Wave
force decreases across the slope, and because there is such a large
spending ground inshore of the kelp bands, the impact component of
waves is weak.
When the sea is rough, large swells crest over the
back of First Slope sO that torrents run down the slope towards the
D. antarctica band. Wave force on both the East Rocks and First
Slope was rated as very strong.
Other samples of D. antarctica were collected from perpendicular
cliff faces between First and Second Slopes. The shore above the
D. antarctica is covered by barnacles and Apophlaea lyalZii Hook.f. et
Harv. For sea surface temperatures see Appendix 1.
(10) Ringaringa (46"54'30"5, 168"9'36"E)
The transect traversed an uneven rock shore, and was similar to
the area at Kean Point.
The Area is protected from southerly and
southwesterly storms, but is exposed to the southeast and east,
although Bench Island, Native Island and The Neck provide some shelter.
Wave force was rated as moderate. Barnacles, limpets and Bostl·ychia
dominate the shore above the D. anta~ctica.