Bioerosion

From Wikipedia, the free encyclopedia

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 (including Lithophaga), sipunculans, polychaetes and phoronids, generating extremely fine sediment of 10 to 100 micrometres. External bioeroders include sea urchins (such as Diadema) and chitons. These forces in concern result in a great deal of erosion. Sea urchin erosion of calcium carbonate 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 with their well developed jaw muscles, tooth armature, and a pharyngeal mill, which grinds up ingested material into sand-sized particles. Bioerosion of coral reef aragonite by parrotfish can range from 1017.7±186.3 kg/yr (0.41±0.07 m³/yr) for Chlorurus gibbus and 23.6±3.4 kg/yr (9.7 10-³±1.3 10-³ m²/yr) for Chlorurus sordidus (Bellwood, 1995).

Bioerosion is also well known in the fossil record on shells and hardgrounds (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).

Trypanites borings in an Upper Ordovician hardground, southeastern Indiana; see Wilson and Palmer (2001).	Petroxestes borings in an Upper Ordovician hardground, southern Ohio; see Wilson and Palmer (2006).	Gastrochaenolites borings in a Middle Jurassic hardground, southern Utah; see Wilson and Palmer (1994).	Numerous borings in a Cretaceous cobble, Faringdon, England; see Wilson (1986).
Sponge borings and encrusters on a modern bivalve shell, North Carolina.	Cross-section of a Jurassic rockground; borings include Gastrochaenolites (some with boring bivalves in place) and Trypanites; Mendip Hills, England; scale bar = 1 cm.

[edit] See also

Geomorphology

Ocean

[edit] References

Bellwood, D. R. (1995). "Direct estimate of bioerosion by two parrotfish species, Chlorurus gibbus and C. sordidus, on the Great Barrier Reef, Australia". Marine Biology 121: 419-429. doi:10.1007/BF00349451. ISSN 0025-3162.

Bromley, R. G (1970). "Borings as trace fossils and Entobia cretacea Portlock as an example", in Crimes, T.P. and Harper, J.C. (eds.): Trace Fossils, Geological Journal Special Issue 3, 49-90.

Bromley, R. G. (2004). "A stratigraphy of marine bioerosion", in D. McIlroy (ed.): The application of ichnology to palaeoenvironmental and stratigraphic analysis, Geological Society of London Special Publications 228. London: Geological Society, 455-481. ISBN 1862391548.

Glaub, I.; Golubic, S., Gektidis, M., Radtke, G. and Vogel, K. (2007). "Microborings and microbial endoliths: geological implications", in Miller III, W (ed): Trace fossils: concepts, problems, prospects. Amsterdam: Elsevier, pp. 368-381. ISBN 0444529497.

Glaub, I.; Vogel, K. (2004). "The stratigraphic record of microborings". Fossils & Strata 51: 126-135. ISSN 0300-9491.

Palmer, T. J. (1982). "Cambrian to Cretaceous changes in hardground communities". Lethaia 15: 309-323. doi:10.1111/j.1502-3931.1982.tb01696.x. ISSN 0024-1164.

Taylor, P. D.; Wilson, M. A. (2003). "Palaeoecology and evolution of marine hard substrate communities". Earth-Science Reviews 62 (1-2): 1-103. doi:10.1016/S0012-8252(02)00131-9. ISSN 0012-8252.

Wilson, M. A. (1986). "Coelobites and spatial refuges in a Lower Cretaceous cobble-dwelling hardground fauna". Palaeontology 29: 691-703. ISSN 0031-0239.

Wilson, M. A. (2007). "Macroborings and the evolution of bioerosion", in Miller III, W (ed): Trace fossils: concepts, problems, prospects. Amsterdam: Elsevier, pp. 356-367. ISBN 0444529497.

Wilson, M. A.; Palmer, T. J. (1994). "A carbonate hardground in the Carmel Formation (Middle Jurassic, SW Utah, USA) and its associated encrusters, borers and nestlers". Ichnos 3: 79-87. ISSN 1042-0940.

Wilson, M. A.; Palmer, T. J. (2001). "Domiciles, not predatory borings: a simpler explanation of the holes in Ordovician shells analyzed by Kaplan and Baumiller, 2000". Palaios 16 (5): 524-525. doi:10.1669/0883-1351(2001)016<0524:DNPBAS>2.0.CO;2. ISSN 0883-1351.