Environmental Engineering Reference
In-Depth Information
Chapter 8
Microbioerosion
Max Wisshak
1
Senckenberg am Meer, Marine Research Department, Wilhelmshaven, Germany
1
Corresponding author: e-mail: max.wisshak@senckenberg.de
1. INTRODUCTION
Barely visible to the naked eye, a diverse assemblage of microborings—alongside
the paleoenvironmental information encoded by them—may be encountered on
the spatial scale of a thumbnail-sized shell fragment. These microbioerosion
features are less than a millimeter in size with tunnel diameters of commonly less
than a hundred microns and are being produced by euendolithic microorganisms,
including bacteria, cyanobacteria, chlorophytes, rhodophytes, and fungi, which
either find shelter from grazers and physical disturbances or seek nutrition within
the mineralized substrate they dissolve (
Golubic et al., 1975, 1981
). Most micro-
borings perfectly match the outline of the organisms producing them and can thus
be assigned to their living tracemaker with a fair degree of confidence (
Radtke,
1991
). A favorable concert of evolutionary longevity and environmental depen-
dency make them superb paleoenvironmental indicators for all Phanerozoic strata
that contain fossil skeletal material in a proper quality of preservation (
Glaub and
Vogel, 2004; Glaub et al., 2007; Vogel and Glaub, 2004
).
Since 90% of, for instance, the known Carboniferous microboring ichnotaxa
are still found in today's oceans (
Wisshak et al., 2008
), neoichnological obser-
vations regarding their physiological and ecological demands of their producers
allow a proper characterization of these paleoenvironmental indicators. Keep-
ing the obligatory reservations concerning an actualistic approach in mind, such
as possible evolutionary changes in ecological demands of certain biota, is of
course mandatory. It is worth mentioning that microbioerosion is not limited
to calcareous substrates, which have received by far the most attention, but
microbial boring activity has been reported also from wood (
Genise, 2004
),
bone (
Jans, 2008
), conodonts (
Glaub and K¨nigshof, 1997
), and even magmatic
rocks (
McLoughlin et al., 2008
).
The aim of this chapter is to provide the sedimentologist, ichnologist, or
paleoecologist with a comprehensive overview on microboring biota and the
trace fossils they produce. This is complemented by a detailed account on the
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