Biology Reference
In-Depth Information
The cold-temperate region of southern Australia (Victoria) and Tasmania is
characterized by the dominance of fucoids, such as
Durvillaea potatorum
in the
upper sublittoral zone in sites with high wave exposure (Cheshire and Hallam
1988
)
(Fig.
14.2
). At medium-exposed sites the fucalean
Phyllosphora comosa
and the
kelps
Macrocystis pyrifera
(former
M. angustifolia
) and
Ecklonia radiata
are
common. In the intertidal zone,
Porphyra
dominate at higher locations, while at
lower intertidal zones, the fucoid
Hormosira banksii
is abundant coexisting with
green algae (e.g.,
Codium
) and the Rhodophyta
Corallina
. Below the fringe of
H. banksii
, in the eulittoral zone
Cystophora torulosa
is the dominant fucoid. In
southern Tasmania,
M. pyrifera
can form dense sublittoral forests in some
locations, the upper sublittoral zone being dominated by
D. potatorum
and the
endemic
Lessonia corrugata
. In general, many of the dominant fucoids are
restricted to cold-temperate waters, and only
P. comosa
and
H. banksii
have
distribution along the warm-temperate eastern coast of Australia (to a latitude
32
S). The northern limit of
D. potatorum
is at latitude 36
S,
M. pyrifera
(former
M. angustifolia
) extending to the northern border of Victoria (L
uning
1990
).
Large brown algae, due to their size and foundational character, have been a special
topic in many ecological studies (Sanderson and Thomas
1987
). In the east coast of
Tasmania, the sea urchins
Heliocidaris erythrogramma
and
Centrostephanus
rodgersii
and the abalone
Haliotis rubra
regulate the population dynamics of various
canopy-forming algae such as
Phyllospora comosa
and
Ecklonia radiata
(Valentine
and Johnson
2005
; Ling and Johnson
2009
)
.
Interestingly, the sea urchin barren zone is
rapidly colonized by the introduced kelp
Undaria pinnatifida
(Valentine and Johnson
2004
,
2005
). In Tasmania, overgrazing of seaweeds by introduced sea urchin
Centrostephanus rodgersii
together with oceanographic changes is causing dramatic
decline in the giant kelp beds (Johnson et al.
2011
).
€
14.2.4 Southern New Zealand Region
Coasts of New Zealand represent areas of high seaweed diversity (Norton et al.
1996
; Kerswell
2006
). A recent account indicated that of the 770 currently known
seaweed species, 265 are endemic (34%) and 22 alien (2.9%) (Hurd et al.
2004
).
According to the revision of Parsons (
1985
), the South Island hosts around 497
species, while for the North Island 555 species were reported. Rhodophyta accounts
for around 60% of the total taxa, Chlorophyta and Phaeophyceae each contributing
with approximately 20% (Parsons
1985
). Within the cold-temperate southern New
Zealand region are included the South Island, the southern part of the North Island,
and the Stewart Island. Also the sub-Antarctic islands Auckland, Campbell, Antip-
odes, and Bounty, as well as the Chatham Island, are in this region (Fig.
14.2
).
Although lower in number compared to green and red algae, brown algae,
particularly fucoids, dominate the rocky shores of Southern New Zealand, while
only few kelps can be regarded as dominant organisms (Schiel
1990
) (Fig.
14.2
). In
the middle and lower intertidal zone,
Cystophora torulosa
and
Landsburgia
