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Hard Coral (hard + coral)
Selected AbstractsComplementary (secondary) metabolites in a soft coral: sex-specific variability, inter-clonal variability, and competitionMARINE ECOLOGY, Issue 3 2006Beatriz Fleury Abstract Sex-specific interactions involving competition for space between the dioecious alcyonacean soft coral Sarcophyton glaucum and the scleractinian coral Acropora robusta were assessed experimentally on Bald Rock, central region of the Great Barrier Reef. To examine this, plus inter-clonal responses, one male colony of S. glaucum, known to produce sarcophytoxide as its predominant complementary (secondary) metabolite, was sectioned, producing 10 clones. The same was done for a female colony. These two sets of clones were then relocated to grids and placed in contact with Acropora clones. Relocated and non-relocated controls were also monitored. High levels of tissue necrosis were observed in the hard coral under contact conditions with both the male and female clones after 20 days. The development of a protective polysaccharide layer in the alcyonacean was also observed. Differences observed in the concentrations of complementary metabolites within the two different S. glaucum colonies were related to sex. Both under competition and non-competition conditions, females exhibited significantly higher concentrations of sarcophytoxide than males, and this increased with time. Fatty ester concentration was also higher in females than males, varying significantly through time, and falling dramatically just after spawning. Fatty ester concentrations decreased linearly through time in the male clones. When involved in competition for space, females possessed higher concentrations of fatty esters than males, both at the site of contact and in non-contact sites, again, decreasing after spawning. No significant changes in sarcophytoxide levels were noted in the parental colonies, but such changes were observed in fatty esters, with the female producing higher concentrations until after spawning. The use of these two variates in the form of a ratio (sarcophytoxide concentration:fatty ester concentration) yielded a variable Rho (,) which was a more sensitive indicator of biochemical change than either of its components alone. These two sets of compounds appeared to have a negative association through time and varied highly significantly between sexes. The diterpene sarcophytoxide may be considered an allelopathic or stress metabolite, while the lipids act as energy storage metabolites. [source] Differences in benthic cover inside and outside marine protected areas on the Great Barrier Reef: influence of protection or disturbance history?AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009Monique R. Myers Abstract 1.Marine protected areas (MPAs) are being used increasingly to manage and protect marine resources. Most studies of MPAs have focused on fish. In this study, the influence of MPA protection on coral reef benthic organisms on the Great Barrier Reef (GBR) was investigated. In addition, the interaction between protection and natural disturbance history was examined. 2.Differences in benthic cover inside and outside MPAs were assessed at 15 pairs of Protected and General Use reefs on the GBR using annual monitoring data from the Australian Institute of Marine Science's Long-Term Monitoring Programme (LTMP). At each reef, benthic cover was determined using a benthic video survey at three sites, with each site consisting of five 50,m transect lines separated by at least 250,m running parallel to the reef crest at 6,9,m depth. 3.Benthic cover was related to both protection status and disturbance history, but natural perturbations exerted a stronger influence on benthic cover than did protection status. The influence of natural perturbation was most noticeable for hard coral. 4.Most reefs where no natural disturbance events had occurred (,undisturbed reefs') had higher hard coral cover and lower soft coral cover than General Use reefs. While the high levels of hard coral on Protected reefs may be a result of protection status, it might also have resulted from selection bias that occurred during the initial zoning of the Great Barrier Reef Marine Park (i.e. managers may have given protection status to reefs with high coral cover). 5.These results are likely influenced by the relatively low intensity of human use, both on the Great Barrier Reef in general and at the particular monitoring sites studied. Over time, as local populations and tourism increase, the effect of protection may become more evident at LTMP sites. Copyright © 2009 John Wiley & Sons, Ltd. [source] Experimental Assessment of Coral Reef Rehabilitation Following Blast FishingCONSERVATION BIOLOGY, Issue 1 2005HELEN E. FOX arrecifes de Indonesia; recuperación de arrecife de coral; restauración de arrecifes Abstract:,Illegal fishing with explosives has damaged coral reefs throughout Southeast Asia. In addition to killing fish and other organisms, the blasts shatter coral skeletons, leaving fields of broken rubble that shift in the current, abrading or burying new coral recruits, and thereby slowing or preventing reef recovery. Successful restoration and rehabilitation efforts can contribute to coral reef conservation. We used field experiments to assess the effectiveness of different low-cost methods for coral reef rehabilitation in Komodo National Park (KNP), Indonesia. Our experiments were conducted at three different spatial scales. At a scale of 1 × 1 m plots, we tested three different rehabilitation methods: rock piles, cement slabs, and netting pinned to the rubble. Significantly more corals per square meter grew on rocks, followed by cement, netting, and untreated rubble, although many plots were scattered by strong water current or buried by rubble after 2.5 years. To test the benefits of the most successful treatment, rocks, at more realistic scales, we established 10 × 10 m plots of rock piles at each of our nine sites in 2000. Three years after installation, coverage by hard corals on the rocks continued to increase, although rehabilitation in high current areas remained the most difficult. In 2002 rehabilitation efforts in KNP were increased over 6000 m2 to test four rock pile designs at each of four rubble field sites. Assuming that there is an adequate larval supply, using rocks for simple, low-budget, large-scale rehabilitation appears to be a viable option for restoring the structural foundation of damaged reefs. Resumen:,La pesca ilegal con explosivos ha dañado a arrecifes de coral en el sureste de Asia. Además de matar a peces y otros organismos, las explosiones destruyen esqueletos de corales, dejando campos de escombros rotos que se mueven con la corriente, erosionando o enterrando a reclutas de coral nuevos y por lo tanto disminuyen o previenen la recuperación del coral. Esfuerzos exitosos de restauración y rehabilitación pueden contribuir a la conservación de arrecifes de coral. Usamos experimentos de campo para evaluar la efectividad de diferentes métodos de bajo costo para la rehabilitación de arrecifes de coral en el Parque Nacional Komodo (PNK), Indonesia. Desarrollamos nuestros experimentos en tres escalas espaciales diferentes. A una escala de parcelas de 1 x 1 m, probamos tres métodos de rehabilitación: pilas de rocas, losas de cemento y redes sobre el escombro. Crecieron significativamente más corales por metro cuadrado sobre rocas, seguido por el cemento, redes y escombro sin tratamiento, aunque muchas parcelas fueron dispersadas por la fuerte corriente de agua o enterradas por escombros después de 2.5 años. Para probar los beneficios del tratamiento más exitoso, rocas, a escalas más realistas, en 2000 establecimos parcelas de 10 x10 m con pilas de rocas en cada unos de nuestros nueve sitios. Tres años después, la cobertura de corales duros sobre las rocas continuó incrementando, aunque la rehabilitación en áreas con corrientes fuertes fue la más difícil. En 2002, los esfuerzos de rehabilitación en PNK se incrementaron a 6000 m2 para probar cuatro diseños de pilas de rocas en cada uno de los cuatro sitios con escombros. Asumiendo que hay una adecuada existencia de larvas, la utilización de rocas para rehabilitación simple, de bajo costo y gran escala parece ser una opción viable para la restauración de la base estructural de arrecifes dañados. [source] Declines in the abundance of Chaetodon butterflyfishes following extensive coral depletionJOURNAL OF FISH BIOLOGY, Issue 5 2006M. S. Pratchett This study documented temporal variation in the abundance of butterflyfishes (Chaetodontidae) at Trunk Reef, on the central Great Barrier Reef, Australia, from May 2000 to March 2005. During this period, live coral cover declined by >90%, mostly due to severe coral bleaching. There were no short-term changes (within 4 months) in the abundance of butterflyfishes following initial declines in live coral cover. Surveys conducted in 2005, however, revealed significant declines in the abundance of Chaetodon baronessa, Chaetodon lunulatus, Chaetodon trifascialis, Chaetodon plebeius and Chaetodon rainfordi, all of which are obligate hard-coral feeders. In contrast, there was no significant change in the abundance of Chaetodon auriga, Chaetodon aureofasciatus, Chaetodon citrinellus, Chaetodon melannotus or Chaetodon vagabundus, which are much less reliant on scleractinian coral for food. Clearly, extensive coral depletion, such as that caused by severe coral bleaching, can have a major effect on the abundance of butterflyfishes. Specific responses of butterflyfishes varied according to their reliance on hard corals for food and their ability to utilize alternate prey types. [source] | ||||||||||