407937
Reports
freehand sections cut from the wood immediately upon its removal from the
natural environment. Sections are cut
parallel to the surface, tangential to the
surface, and wherever possible, along the
length of Limnoria burrows. In contrast
to the authors of the previous reports,
we do not find that marine fungi are
universal inhabitants of submerged or
floating wood; on the other hand, bac-
Possible Relation between
Marine Fungi and Limnoria
Attack on Submerged Wood
Abstract. Wood submerged in the sea
at Friday Harbor and at Naples contained
only occasional hyphae, which showed
no relationship to Limnorta burrows. Cultures of Limnoria established in “unconditioned” wood and in autoclaved wood
were maintained in the absence of fungi.
These results indicate that marine fungi
have no significance for the activities of
Limnoria.
those reported in the publications cited
above. Since the suggestion that marine
fungi may have a primary role in wood
deterioration in the sea has serious economic implications, we feel that it is
necessary to make our findings a matter
of record.
The question of a possible relationship
between marine fungi and marine wood
borers wasraised and discussed at the Friday Harbor Symposium on Marine Bor-
teria, some of which are undoubtedly
cellulolytic, are nearly always present in
the superficial wood fibers. That marine
fungi do occasionally occur cannot be denied, but the presence of recognizable
mycelium in wood freshly removed from
the sea is uncommon indeed. Further,
when fungi are present we find no evi-
dence for a topographical relationship
with Limnoria burrows. No significant
differences could be seen between the
cold temperate environmentof the North
Pacific and the warm subtropical condi-
ing and Fouling Organisms, and much of
the supporting evidence was published
in the proceedings of that conference
opinion that when a marine fungus does
fested with marine fungi. Believing that
fungal infection always occurs prior to
attack by marine wood borers, especially
wood when submergedin the sea is universally and rapidly attacked by marine
fungi; (ii) that wood is not attacked by
significance for the activities of Limnorta.
Laboratory cultures of Limnoria, set
up for breeding experiments, have been
might be a relationship between fungi
merged for a period of time sufficient to
kept for 10 months in the sea-water system at Friday Harbor and show only
Limnoria is unable to survive in wood
that has been sterilized by autoclaving.
50 cultures of animals living in Douglas
fir and western yellow pine. In an effort
reported (7, 3) that fungi appeared on
woodentest panels exposed in more than
63 stations in the Western Hemisphere,
and vigorous sporulation by ascomycetous fungi may occur after 2 to 3 weeks’
Kolle flasks containing sterile sea water
and autoclaved wood were each inoculated with 25 specimens of Limnoria, and
to half of these a solution of penicillinstreptomycin was added. In the latter,
bacteria have been suppressed, fungi
have grown, and very few Limnoria have
contained fungal mycelium in the surface
dence of fungal infection, and the antmals are healthy and vigorous and have
established growing populations. These
In the 8 Nov. 1957 issue of Science,
Meyers and Reynolds (/) reported that
wood submerged in the sea is soon in-
(6). The hypothesis rests mainly upon
the following observations: (i) that
that there
Limnoria until after it has been sub-
and wood-destroying animals. Becker,
Kampf, and Kohimeyer (2), at about
“condition” the surface layers; (111) that
Limnoria, they suggested
the same time, published the results of
extensive observations and experiments
that had led them to the same conclusion. Further work in support of this
hypothesis was reported by Reynolds and
Meyers (3) and by Schafer and Lane
(4). In each case it was stated, sug-
gested, or implied that marine woodboring animals do not attack wood or
becomeestablished in it unless the wood
is first invaded and “conditioned” by
marine fungi.
Because we believe that the evidence
so far presented is insufficient to build a
sound case, we undertook to examine the
problem (5). From our studies, carried
out at the Friday Harbor Laboratories of
the University of Washington and at the
Stazione Zoologica di Napoli, we have
been unable to obtain results similar to
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9 JANUARY 1959
Concerningthefirst observation, it was
and that at Biscayne Bay the infection
may be extensive in less than a week
submergence. Working with laboratory
cultures, Becker (2) recorded that all
samples of both softwood and hardwood
layers and in the vicinity of Limnoria
burrows after a submergence period of
several weeks. It was also reported that
wood samples collected from the North
Sea, the Mediterranean, and the Indian
Ocean regularly contained fungi.
We have examined, both at Friday
Harbor and at Naples, wood that was
collected at random from thesea, including pieces with and without Lim-
tions of the Mediterranean. It is our
invade wood its presence is fortuitous so
far as any relationship with Limnoria is’
concerned, and that these fungi have no
four cases of fungal infestation out of
to obtain fungi in laboratory cultures, 10
survived; in the controls there is no evi-
cultures have been maintained for 8
months,
The idea (observation ii) that Lim-
norta will not attack wood until its surface has been “conditioned” is based
upon field observations (/-3) that there
is a lag of some days, weeks, or even
months between the time that wood is
placed in the sea and the time when
noria burrows, samples that appear to be
relatively fresh, some that are water-
wood borers begin their invasion. During:
this interval microorganisms, especially
bacteria, do indeed appear in the super-
others that are soft, spongy, and extensively deteriorated. We have also, again
in both locations, placed blocks of fresh,
facts do not establish that Limnoria is
soaked from
long submergence, and
fungus-free Douglas fir and western yellow pine into the sea at intervals so that
they could be studied after known periods of submergence (up to 8 months at
Friday Harbor; up to 5 months in the
Bay of Naples). The procedure has been
to make microscopic examination of thin
ficial wood fibers and may begin to deteriorate them; this is apparently what
is meant by “conditioning.” But these
unable to attack fresh wood or that such
surface softening enhances the likeli-
hood of Limnoria attack. It is not an un-
expected finding that, in the natural esvironment, time should elapse before
wood borers appear, since these dnimals
are not constantly present, swimming
93