| Registro completo |
| Provedor de dados: |
ArchiMer
|
| País: |
France
|
| Título: |
Internal bioerosion of Acropora formosa in Reunion (Indian Ocean): microborer and macroborer activities
|
| Autores: |
Zubia, M
Peyrot-clausade, M
|
| Data: |
2001-05
|
| Ano: |
2001
|
| Palavras-chave: |
Acropora
Bioérosion
Organismes perforants
Récifs coralliens
Océan Indien
Acropora
Bioerosion
Boring organisms
Coral reef
Indian Ocean
|
| Resumo: |
Bioerosion by grazing and boring organisms is one of the major destructive forces operating on reef. The aim of this study was to estimate the intensity of internal bioerosion by both microflora and fauna of Acropora, a branching scleractinian, on the reef flat at La Saline (Reunion, Indian Ocean). Internal bioerosion was estimated at two sites, varying in degrees of eutrophication. At each site, dead Acropora subjected to heavy grazing or covered by algal turf were examined. Acropora formosa is subjected to high bioerosion due to its high porosity and its branching form, which facilitates colonisation by boring organisms. Three endolithic microflora species, Plectonema terebrans, Mastigocoleus testarum and Ostreobium queckettii colonised the branches. The mean density of polychaetes was high (72 individuals cm(-3)), and all were regarded as meiofauna (diameter < 0.5 mm). The main agents of bioerosion of Acropora formosa were boring microflora whose baring activities were four times greater (0.29 g cm(-3) of CaCO3) than that recorded by the boring fauna (0.07 g cm(-3) of CaCO3). Under high levels of eutrophication, the microflora were responsible for high bioerosion (30.8% of the surface of the substrate). In contrast, the composition of the fauna changed under these conditions but not the rate of bioerosion (4.4% maximum of the volume of dead Acropora). At the undisturbed site, the substrate covered by algae (within damselfish territory and therefore not subjected to grazing) had low levels of bioerosion caused by microflora (18.9% of the surface) and high bioerosion by fauna (9.5% maximum of the volume of dead Acropora) and in addition the composition of boring fauna was different to that found at the disturbed site with sipunculans being the dominant agent of bioerosion (6 individuals cm(-3) maximum).
La bioérosion par les organismes brouteurs et perforants est un processus majeur dans la destruction des récifs coralliens. Le but de cette étude est dˈestimer lˈintensité de la bioérosion interne dˈAcropora formosa par la microflore et la microfaune sur le récif de La Saline. La bioérosion interne est étudiée sur deux sites en fonction du degré dˈeutrophisation et du type de recouvrement du substrat (brouté ou recouvert dˈun gazon algal). La bioérosion dˈA. formosa est très élevée en raison de sa très forte porosité et de sa forme branchue, qui augmente la surface disponible à la colonisation par les perforants. Plectonema terebrans, Mastigocoleus testarum et Ostreobium queckettii sont les trois espèces principales de la microflore endolithique qui colonisent ces branches. Les polychètes, dont la densité moyenne est élevée (72 individus cm–3), appartiennent à la meiofaune (diamètre < 0,5 mm). La bioérosion résulte principalement de lˈactivité de la microflore (0,29 g cm–3 de CaCO3) qui est 4 fois supérieure à celle de la meiofaune (0,07 g cm–3 de CaCO3). En milieu eutrophisé, 30,8% de la surface du squelette est perforée par la microflore et 4,4% du volume érodé par la meiofaune. En milieu témoin, le plus faible pourcentage de bioérosion (18,9%) par la microflore est relevé dans les substrats couverts de feutrage algal alors que la bioérosion par la faune atteint 9,5% du volume du squelette due principalement à lˈactivité des siponcles (6 individus cm–3).
|
| Tipo: |
Text
|
| Idioma: |
Inglês
|
| Identificador: |
http://archimer.ifremer.fr/doc/00322/43353/42860.pdf
DOI:10.1016/S0399-1784(01)01144-6
http://archimer.ifremer.fr/doc/00322/43353/
|
| Editor: |
Gauthier-villars/editions Elsevier
|
| Formato: |
application/pdf
|
| Fonte: |
Oceanologica Acta (0399-1784) (Gauthier-villars/editions Elsevier), 2001-05 , Vol. 24 , N. 3 , P. 251-262
|
| Direitos: |
2001 Ifremer/CNRS/IRD/Éditions scientifiques et médicales Elsevier SAS
info:eu-repo/semantics/openAccess
restricted use
|
|
