Biology Reference
In-Depth Information
loss of more than 90%. Growth rates after reimmersion in seawater depend on the
thallus water content and the length of the desiccation period. Few ultrastructural
changes were found after desiccation, but the very thick cell walls of the species and
the absence of vacuoles are regarded as prerequisites for surviving periods of
desiccation (Jacob et al.
1992
).
13.4 Ecology of Polar Seaweed Communities
13.4.1 Biomass, Depth Distribution, and Productivity
As a result of the harsh environmental conditions, most seaweeds of the polar
regions occur almost entirely in the sublittoral. In Antarctica, seaweeds dominate
shallow benthic communities on hard substrates along the northern portion of the
western Antarctic Peninsula and adjacent islands, often covering over 80% of the
bottom with standing biomass levels in the range of 5-10 wet kg m
2
, which is
comparable to temperate kelp forests (Amsler et al.
1995
; Brouwer et al.
1995
;
Quartino et al.
2001
; Quartino and Boraso de Zaixso
2008
). Low intertidal pools
and crevices in the upper sublittoral are frequently colonized by the red algae
Iridaea cordata
and
Palmaria decipiens
. Below this zone several species of large,
perennial brown algae are particularly abundant.
Desmarestia menziesii
(shallower)
and/or
D. anceps
(deeper) typically dominate in waters from 2 to 3 m down to
approximately 10-20 m with
D. anceps
sometimes the dominant species to 30 m or
more.
Himantothallus grandifolius
typically dominates from whatever depth at
which the
Desmarestia
spp. thin out down to 40 m or greater (DeLaca and Lipps
1976
; Zielinski
1990
;Kloser et al.
1994
; Amsler et al.
1995
; Brouwer et al.
1995
;
Quartino et al.
2001
) with productivity estimates in the northern part of its range
estimated as 16-56 g C m
2
year
1
(Drew and Hastings
1992
).
Cystosphaera
jacquinotii
often co-dominates with
H. grandifolius
or
D. anceps
below 20 m in
relatively wave-exposed areas (Zielinski
1990
; Chung et al.
1994
; Amsler personal
observations). These brown algal stands are accompanied by various undergrowth
species, besides the mentioned
P. decipiens
and
I. cordata
, the red algae
Gigartina
skottsbergii, Myriogramme manginii
,
M. smithii
,
Trematocarpus antarcticus
,
Gymnogongrus turquetii
,
Georgiella confluens
, and others (Wiencke and Clayton
2002
; Wulff et al.
2011
). In total, over 100 species of seaweeds are found in shallow
water along the Antarctic Peninsula (Moe and DeLaca
1976
;Kl
oser et al.
1996
;
€
Wiencke and Clayton
2002
).
This general pattern of seaweed dominance is reported from numerous locations
along the western Antarctic Peninsula region from its northeastern limit at Signy
Island (60
S latitude) south to Anvers Island (64
S; e.g., Neushul
1965
; Del´pine
et al.
1966
; DeLaca and Lipps
1976
; Lamb and Zimmerman
1977
; Rakusa-
Suszczewski and Zielinski
1993
; Amsler et al.
1995
; Brouwer et al.
1995
;Kl
€
oser
et al.
1996
; Quartino et al.
2001
). However,
the limited reports of seaweed
