BIOEROSION

'Bioerosion' describes the erosion of hard ocean substrates by living organisms by a number of mechanisms. Bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish. It can occur on coastlines, on coral reefs, and on ships. Mechanisms of bioerosion include biotic boring, drilling, rasping, and scraping.
Bioerosion of coral reefs generates the fine and white coral sand characteristic of tropical islands. The coral is converted to sand by internal bioeroders such as algae, fungi, bacteria (microborers) and sponges (Clionidae), bivalves (Lithophaga), sipunculans (Aspidosiphon), polychaetes (Eunicidae) and phoronids, generating extremely fine sediment of 10 to 100 micrometres. External bioeroders include urchins (Diadema) and chitons (Acanthopleura). These forces in concern result in a great deal of erosion. Sea urchin erosion of CaCO3 has been reported in some reefs at annual rates exceeding 20 kg/m².
Fish also erode coral while eating algae. Parrotfish cause a great deal of bioerosion, due to their well developed jaw muscle and tooth armature, and a pharyngeal mill, which grinds up ingested material into sand-sized particles. Bioerosion of reef calcium carbonate by parrotfish can range from 1017.7±186.3 kg yr-¹ (0.41±0.07 m³ yr-¹) for Chlorurus gibbus and 23.6±3.4 kg yr-¹ (9.7 10-³±1.3 10-³ m²yr-¹) for Chlorurus sordidus (Bellwood, 1995).
Bioerosion is also well known in the fossil record (Bromley, 1970), with traces of this activity stretching back well into the Precambrian (Taylor & Wilson, 2003). Macrobioerosion, which produces borings visible to the naked eye, shows two distinct evolutionary radiations. One was in the Middle Ordovician (the Ordovician Bioerosion Revolution; see Wilson & Palmer, 2006) and the other in the Jurassic (see Taylor & Wilson, 2003; Bromley, 2004; Wilson, 2007). Microbioerosion also has a long fossil record and its own radiations (see Glaub & Vogel, 2004; Glaub et al., 2007).

Contents

See also

References

See also

★ Geomorphology
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★ Biogeomorphology
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★ Coastal erosion

★ Ocean

References

★ Direct estimate of bioerosion by two parrotfish species, ''Chlorurus gibbus'' and ''C. sordidus'', on the Great Barrier Reef, Australia, , D. R., Bellwood, Marine Biology, 1995

★ Trace Fossils, , R. G, Bromley, , 1970,

★ The application of ichnology to palaeoenvironmental and stratigraphic analysis, , R. G., Bromley, Geological Society, 2004,

★ Trace fossils: concepts, problems, prospects, , I., Glaub, Elsevier, 2007,

★ The stratigraphic record of microborings, , I., Glaub, Fossils & Strata, 2004

★ Cambrian to Cretaceous changes in hardground communities, , T. J., Palmer, Lethaia, 1982

★ Palaeoecology and evolution of marine hard substrate communities, , P. D., Taylor, Earth-Science Reviews, 2003

★ Coelobites and spatial refuges in a Lower Cretaceous cobble-dwelling hardground fauna, , M. A., Wilson, Palaeontology, 1986

★ Trace fossils: concepts, problems, prospects, , M. A., Wilson, Elsevier, 2007,

★ A carbonate hardground in the Carmel Formation (Middle Jurassic, SW Utah, USA) and its associated encrusters, borers and nestlers, , M. A., Wilson, Ichnos, 1994

★ Domiciles, not predatory borings: a simpler explanation of the holes in Ordovician shells analyzed by Kaplan and Baumiller, 2000, , M. A., Wilson, Palaios, 2001

★ Patterns and processes in the Ordovician Bioerosion Revolution, , M. A., Wilson, Ichnos, 2006
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Bioerosion Website at The College of Wooster
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Comprehensive bioerosion bibliography compiled by Mark A. Wilson
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