97
barnacles Lepas sp., for example, are emblematic within the reduced diversity of
offshore fouling assemblages. Assemblages also differ as the fouling process
advances with simpler smaller organisms serving as initial pioneer colonizers followed by larger more complex organisms. Bryozoans are among the early colonizers followed by serpulid tube worms, mollusks, and cirripeds. Sessile organisms
that adhere firmly to the surface precede motile free-living benthic organisms such
as shrimps, crabs, or starfish since a suitably complex environment must be present
to host the latter.
Surface colonization by multicellular eukaryotes is modulated by chemical cues
including both inducers, which promote colonization, and deterrents which discourage it (Steinberg et al. 2002). Inducing cues may be released into the water or may
be surface bound. In addition to ACH, small peptides, larger proteins, carbohydrates
and polysaccharides, glycerolipids, and fatty acids have all been found to induce
settlement of a variety of meroplanktonic taxa. Noxious natural substances, such as
halogenated furanones from macroalgae and sponge metabolites or turpentine used
to preserve wooden pilings, are deterrents to the settling of meroplanktonic larvae.
Natural deterrents are usually nonpolar water insoluble compounds concentrated in
the external tegument of benthic organisms.
Substrate colonization occurs through biological succession usually from the
simpler organisms to the more complex. Thus, micro-biofouling progresses from
bacteria to unicellular autotrophs to unicellular heterotrophs. Since dissolved
organic matter rapidly (within hours) adsorbs to clean surfaces immersed in seawater, a suitable substrate for bacterial copiotrophs appears, which organisms, upon
colonization prepare the way for less exacting oligotrophic bacteria. These two
groups in turn create the conditions for colonization by autotrophs (diatoms) by
creating an environment rich in inorganic nutrients, the sum of which can now sustain heterotrophic microorganisms such as ciliates and flagellates. Mature biofilms
set the stage for colonization by fast-growing macroorganisms, mainly hydroids,
bryozoans, serpulids, and ascidians, followed later by slower growing mollusks
(Railkin 2004; Delauney et al. 2010). Motile organisms are the last to appear once a
complex substrate is available. Such climax states may be attained within months to
years depending on the climate and nutrient supply. Juvenile crabs, spiny lobster,
and gobiid fish are regularly seen during annual refurbishing of the CariCOOS
MapCO2 buoy deployed in a tropical coral reef environment.
Of concern to ocean observing is the deterioration of instrument response due to
biofouling, the rate of which depends greatly on the deployment site and deployment mode. Performance of identical instruments deployed in the high productivity
waters at the confluence of the Patuxent River and Chesapeake Bay (Solomons) and
in the low productivity environment of Kaneohe Bay in Hawaii during ACT field
tests differed widely as discussed previously with rapid fouling occurring at the
former site. Vehicles in motion and their instrument payload are subject to differential fouling in accordance to localized turbulence and water velocity. Surfaces subject to uninterrupted laminar flow discourage fouling while recondite, high
turbulence areas favor increased fouling. Biofouling is minimal in the deep sea, one
of the reasons for parking the profiling Argo floats at 2 km depth between ascents.
4.4 Biofouling of Ocean Observing Instruments and Platforms
barnacles Lepas sp., for example, are emblematic within the reduced diversity of
offshore fouling assemblages. Assemblages also differ as the fouling process
advances with simpler smaller organisms serving as initial pioneer colonizers followed by larger more complex organisms. Bryozoans are among the early colonizers followed by serpulid tube worms, mollusks, and cirripeds. Sessile organisms
that adhere firmly to the surface precede motile free-living benthic organisms such
as shrimps, crabs, or starfish since a suitably complex environment must be present
to host the latter.
Surface colonization by multicellular eukaryotes is modulated by chemical cues
including both inducers, which promote colonization, and deterrents which discourage it (Steinberg et al. 2002). Inducing cues may be released into the water or may
be surface bound. In addition to ACH, small peptides, larger proteins, carbohydrates
and polysaccharides, glycerolipids, and fatty acids have all been found to induce
settlement of a variety of meroplanktonic taxa. Noxious natural substances, such as
halogenated furanones from macroalgae and sponge metabolites or turpentine used
to preserve wooden pilings, are deterrents to the settling of meroplanktonic larvae.
Natural deterrents are usually nonpolar water insoluble compounds concentrated in
the external tegument of benthic organisms.
Substrate colonization occurs through biological succession usually from the
simpler organisms to the more complex. Thus, micro-biofouling progresses from
bacteria to unicellular autotrophs to unicellular heterotrophs. Since dissolved
organic matter rapidly (within hours) adsorbs to clean surfaces immersed in seawater, a suitable substrate for bacterial copiotrophs appears, which organisms, upon
colonization prepare the way for less exacting oligotrophic bacteria. These two
groups in turn create the conditions for colonization by autotrophs (diatoms) by
creating an environment rich in inorganic nutrients, the sum of which can now sustain heterotrophic microorganisms such as ciliates and flagellates. Mature biofilms
set the stage for colonization by fast-growing macroorganisms, mainly hydroids,
bryozoans, serpulids, and ascidians, followed later by slower growing mollusks
(Railkin 2004; Delauney et al. 2010). Motile organisms are the last to appear once a
complex substrate is available. Such climax states may be attained within months to
years depending on the climate and nutrient supply. Juvenile crabs, spiny lobster,
and gobiid fish are regularly seen during annual refurbishing of the CariCOOS
MapCO2 buoy deployed in a tropical coral reef environment.
Of concern to ocean observing is the deterioration of instrument response due to
biofouling, the rate of which depends greatly on the deployment site and deployment mode. Performance of identical instruments deployed in the high productivity
waters at the confluence of the Patuxent River and Chesapeake Bay (Solomons) and
in the low productivity environment of Kaneohe Bay in Hawaii during ACT field
tests differed widely as discussed previously with rapid fouling occurring at the
former site. Vehicles in motion and their instrument payload are subject to differential fouling in accordance to localized turbulence and water velocity. Surfaces subject to uninterrupted laminar flow discourage fouling while recondite, high
turbulence areas favor increased fouling. Biofouling is minimal in the deep sea, one
of the reasons for parking the profiling Argo floats at 2 km depth between ascents.
4.4 Biofouling of Ocean Observing Instruments and Platforms