Biology Reference
In-Depth Information
Svirski et al.
1993
), and the extent of the damage is clearly determined by the
intensity of the infections (Cancino et al.
1987
; Buschmann and Gomez
1993
).
Farming of
Gracilaria chilensis
during the last 40 years is a clear example of how
detrimental epiphytes may become (Kuschel and Buschmann
1991
; Pizarro and
Santelices
1993
).
In addition, negative effects on the economic value of brown and red algae infested
by endophytes have been reported (Yoshida and Akiyama
1979
;Apt
1988a
,
b
). The
endophytic phaeophycean
Laminariocolax
(
Streblonema) aecidioides
causes tissue
thickening in the commercially valuable alga
Undaria
sp. (Yoshida and Akiyama
1979
), and
Streblonema
-like endophytes are known to produce galls in some algal
hosts (Andrews
1977
;Apt
1988a
).
Estimates of economic losses for Japan and Korea (Gachon et al.
2010
) are
estimated at about 10% of the annual production (0.15 billion US dollars globally),
mostly due to the oomycete pathogens
Olpidiopsis
spp
.
and
Pythium
spp. (Ding
and Ma
2005
; Park et al.
2000
)
.
However, spatial and interannual variability
feature dramatic variations with reductions of 15-20% and 20-30% in yields and
value, respectively, in South Korea and losses in Japan rose to 64% in 1993
(Gachon et al.
2010
).
Removal of epiphytes can be carried out by physical (mechanical brushing, rapid
water movement), chemical (rinsing in chlorine, copper, or changes in pH), and
biological means (use of epiphyte herbivores). However, type III to type V epiphytes
(see above), as well as endophytes and eukaryotic parasites, cannot be controlled by
such treatments and alternative methods based on the current understanding of the
genetic and biochemical basis of close associations are required in order to limit their
impacts on algal mariculture. Interestingly, a recent study showed that dipping of
seedlings in a commercial extract from
Ascophyllum nodosum
(AMPEP), prior to
out-planting, was efficient for both improving the daily growth rate and increased
productivity of both varieties of
Kappaphycus
and could be used as part of a
management protocol to control or reduce the impact of
Neosiphonia
infection in
commercial cultivation areas in the sea (Borlongan et al.
2011
).
11.4.3 Fouling
The negative effects of intimate associations on macroalgal fitness can be expected
to exert a strong pressure of selection for efficient antifouling defenses. Chemical
resistance against various epibiotic organisms, e.g., bacteria, microalgae, periphy-
ton, fungi, invertebrate larvae, and epiphytic macroalgae, has been tested for all
major macroalgal groups (worth 1.5 billion US dollars globally reviewed in Davis
et al.
1989
; Steinberg and deNys
2002
; Lane and Kubanek
2008
).
Although a wealth of examples on antifouling properties of algal extracts exists,
the generality of antifouling metabolites has been questioned. The problem with
most of the existing studies is that, although they clearly show macroalgae com-
monly containing metabolites with antifouling properties, it is not known whether
