96
platforms. Small marker buoys may even sink under the weight of the aggregated
fouling community. Anticorrosion coatings can also be destroyed by fouling
organisms.
Biofilm or micro-biofouling, a surface coating consisting of various types of
microorganisms embedded in an aqueous mucous sheath, is the precursor to macrobiofouling. When a clean substrate is immersed in seawater, a film of dissolved
organic material (ubiquitous in the marine environment) adsorbs upon the surface
facilitating settlement of pioneering bacterial colonizers (Videla and Herrera 2005).
These in turn promote aggregation of other microorganisms and the formation of
the mucous film via quorum sensing, a chemical communication system consisting
of the secretion and detection of small signaling molecules known as autoinducers
which in turn promote secretion of extracellular polysaccharides (40–95%), proteins, DNA, lipids, and other substances. Microorganisms embedded within the
biofilm exhibit enhanced resistance to antibiotics and biocides.
Bacterial biomass by far dominates biofilm colony composition with prominent
presence and role for the Proteobacteria. Roseobacter and Alteromonas, members
of the Proteobacteria associated to marine snow, are among the primary early colonizers. Pennate diatoms, notably the genera Nitzschia, Amphora, Cylindrotheca,
and Navicula, constitute the second most abundant group of microorganisms.
Cyanobacteria of the genera Synechococcus and Oscillatoria, green flagellates, heterotrophic microflagellates, and dinoflagellates may also constitute part of the biofilm community.
Extracellular polysaccharides have been isolated from culture of a number of
marine bacterial genera including Vibrio, Pseudomonas, Lactobacillus, and
Weissella. Most produce heteropolymers containing glucose, galactose, rhamnose,
mannose and other pentoses, hexoses, hexsosamines, and uronic acids, the so-called
mucopolysaccharides or glycosaminoglycans. These compounds constitute the
gelatinous matrix of the biofilm. Autoinducers are principally of the acylhomoserine (AHL) family of compounds. Secretion of AHL into the medium promotes phenotypic changes of otherwise free-living bacteria which enhance bacterial adhesion,
polysaccharide biosynthesis, colony formation, and enhanced surface motility (Di
Donato et al. 2016; Steinberg et al. 2002). Free-living flagellate forms are known to
lose the flagellae upon settling.
Mature fouling assemblages host animals of most phyla including the simpler
sponges and bryozoans; coelenterates such as hydroids and corals; segmented serpulid tube worms; crustaceans such as barnacles, pedunculated goose barnacles
(cirripeds); various species of decapods including shrimps, crabs, and lobsters; mollusks such as mussels and oysters; echinoderms; and lower chordates (tunicates),
together with a diversity of macroalgae. All are characterized by a meroplanktonic
lifestyle, in which larvae are planktonic but metamorphosis precipitates settling
onto a substrate followed by development of the adult life form. Community composition and diversity depend in large part on geographic location. Arctic assemblages for example differ substantially from their tropical counterparts, and fouling
communities in nearshore waters similarly differ from those developing upon
surfaces moored, floating or traversing the surface of the deep ocean. Pelagic goose
4 Environmental Constraints to Instrumental Ocean Observing: Power Sources…
platforms. Small marker buoys may even sink under the weight of the aggregated
fouling community. Anticorrosion coatings can also be destroyed by fouling
organisms.
Biofilm or micro-biofouling, a surface coating consisting of various types of
microorganisms embedded in an aqueous mucous sheath, is the precursor to macrobiofouling. When a clean substrate is immersed in seawater, a film of dissolved
organic material (ubiquitous in the marine environment) adsorbs upon the surface
facilitating settlement of pioneering bacterial colonizers (Videla and Herrera 2005).
These in turn promote aggregation of other microorganisms and the formation of
the mucous film via quorum sensing, a chemical communication system consisting
of the secretion and detection of small signaling molecules known as autoinducers
which in turn promote secretion of extracellular polysaccharides (40–95%), proteins, DNA, lipids, and other substances. Microorganisms embedded within the
biofilm exhibit enhanced resistance to antibiotics and biocides.
Bacterial biomass by far dominates biofilm colony composition with prominent
presence and role for the Proteobacteria. Roseobacter and Alteromonas, members
of the Proteobacteria associated to marine snow, are among the primary early colonizers. Pennate diatoms, notably the genera Nitzschia, Amphora, Cylindrotheca,
and Navicula, constitute the second most abundant group of microorganisms.
Cyanobacteria of the genera Synechococcus and Oscillatoria, green flagellates, heterotrophic microflagellates, and dinoflagellates may also constitute part of the biofilm community.
Extracellular polysaccharides have been isolated from culture of a number of
marine bacterial genera including Vibrio, Pseudomonas, Lactobacillus, and
Weissella. Most produce heteropolymers containing glucose, galactose, rhamnose,
mannose and other pentoses, hexoses, hexsosamines, and uronic acids, the so-called
mucopolysaccharides or glycosaminoglycans. These compounds constitute the
gelatinous matrix of the biofilm. Autoinducers are principally of the acylhomoserine (AHL) family of compounds. Secretion of AHL into the medium promotes phenotypic changes of otherwise free-living bacteria which enhance bacterial adhesion,
polysaccharide biosynthesis, colony formation, and enhanced surface motility (Di
Donato et al. 2016; Steinberg et al. 2002). Free-living flagellate forms are known to
lose the flagellae upon settling.
Mature fouling assemblages host animals of most phyla including the simpler
sponges and bryozoans; coelenterates such as hydroids and corals; segmented serpulid tube worms; crustaceans such as barnacles, pedunculated goose barnacles
(cirripeds); various species of decapods including shrimps, crabs, and lobsters; mollusks such as mussels and oysters; echinoderms; and lower chordates (tunicates),
together with a diversity of macroalgae. All are characterized by a meroplanktonic
lifestyle, in which larvae are planktonic but metamorphosis precipitates settling
onto a substrate followed by development of the adult life form. Community composition and diversity depend in large part on geographic location. Arctic assemblages for example differ substantially from their tropical counterparts, and fouling
communities in nearshore waters similarly differ from those developing upon
surfaces moored, floating or traversing the surface of the deep ocean. Pelagic goose
4 Environmental Constraints to Instrumental Ocean Observing: Power Sources…