Biology Reference
In-Depth Information
initially described as
Streblonema macrocystis
(Peters
1991
). Recent results
showed that galls affecting natural populations of
Lessonia nigrescens
were
associated with the infection by a filamentous brown algal endophyte of the
genus
Laminariocolax
(Thomas et al.
2009
).
Similar patterns of few filamentous algae growing subtidally except within the
thalli of the larger chemically defended macroalgae were also observed by Peters
(
2003
) in Antarctica. The endophytes were highly palatable to the amphipod
Gondogeneia antarctica
, suggesting that these filamentous endophytes obtain
some protection from mesograzers by growing in association with unpalatable
macroalgae (Amsler et al.
2009
). These data suggest that macroalgae along the
western Antarctic Peninsula rely on grazers to control populations of potentially
harmful epiphytes. These results strongly suggest that the chemically defended
macroalgal flora lives in mutualism with high densities of mesograzers, providing
amphipods with shelter from predation while continually being cleaned of poten-
tially harmful endo/epiphytes (Aumack et al.
2011
).
11.2.2.3 Endophytes in Green Algae
Reports on the occurrence of algal endophytes in green algae are scarce. The
endophytic filamentous green alga
Acrochaete geniculata
was identified as the
causative agent of a disease affecting tank-cultivated
Ulva rigida
(Del Campo
et al.
1998
). This destructive disease is characterized by green spots, initially
located at the basis of the thalli that spread through the host and gradually cause
perforations of the frond (Del Campo et al.
1998
). Advanced stages of infection
result in frond wrinkling and severe tissue loss. Infection is transmitted within
2 weeks when healthy and diseased fronds are cocultivated, whereas previous trials
to infect the host in the laboratory with actively reproducing suspensions of the
endophyte remained unsuccessful (Del Campo et al.
1998
).
11.2.2.4 Life History Stages of Seaweeds as Endophytic Filaments
in Other Taxa
Kelp Gametophytes in Red Filamentous Algae
Kelp gametophytes have been extensively studied in the laboratory, but are elusive
in nature. They have occasionally been found growing on rocks, and wood, and as
epiphytes on crustose coralline algae (Parke
1932
; Sakai and Funano
1964
; Funano
1969
; Kaneko
1973
; Kain
1979
). Artificial substrata placed in nature have also
successfully been utilized for settlement of kelp gametophytes (e.g., Reed et al.
1988
). More recently, gametophytes have been found growing endophytically in
the cell walls of red algae where they become reproductive and produced juvenile
sporophytes (Garbary et al.
1999a
,
b
). Initially, 17 red algal species from western
North America were observed with endophytic kelp gametophytes. They were most
common in filamentous hosts, and hundreds of gametophytes were observed in
