Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), ...Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), copper(Cu), molybdenum(Mo), manganese(Mn), lead(Pb), tin(Sn), titanium(Ti), vanadium(V), and yttrium(Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea(SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.展开更多
Extensive bleaching of Montastrea annularis spp. group and several other scleractinian taxa occurred on the reefs within the Arrecifes de Cozumel National Park of Cozumel, Mexico, after the passage of Hurricane/Tropic...Extensive bleaching of Montastrea annularis spp. group and several other scleractinian taxa occurred on the reefs within the Arrecifes de Cozumel National Park of Cozumel, Mexico, after the passage of Hurricane/Tropical Storm Rina. We conducted six drift dives at five different dive sites （-13 h of scuba diving） and photographed a variety of reefs scenes at depths of 10-28 m. Bleaching was noted at depths of 10-40 m in a variety of scleractinian species, including M. annularis species group, especially M. faveolata and Siderastrea siderea. Considering that local dive guides had not observed bleaching prior to the storm and the sea surface temperature did not exceed the local bleaching threshold, it is probable that the extensive rainfall associated with Hurricane/Tropical Storm Rina lowered salinity sufficiently via subsurface freshwater springs to cause bleaching in susceptible species. This suggests the need to monitor not only subsurface sea temperature but also subsurface salinity in localities where freshwater springs occur adjacent to or within coral reefs.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(No.2013CB956103)the National Science Foundation of China(Nos.41306109,41476038)
文摘Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), copper(Cu), molybdenum(Mo), manganese(Mn), lead(Pb), tin(Sn), titanium(Ti), vanadium(V), and yttrium(Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea(SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.
文摘Extensive bleaching of Montastrea annularis spp. group and several other scleractinian taxa occurred on the reefs within the Arrecifes de Cozumel National Park of Cozumel, Mexico, after the passage of Hurricane/Tropical Storm Rina. We conducted six drift dives at five different dive sites （-13 h of scuba diving） and photographed a variety of reefs scenes at depths of 10-28 m. Bleaching was noted at depths of 10-40 m in a variety of scleractinian species, including M. annularis species group, especially M. faveolata and Siderastrea siderea. Considering that local dive guides had not observed bleaching prior to the storm and the sea surface temperature did not exceed the local bleaching threshold, it is probable that the extensive rainfall associated with Hurricane/Tropical Storm Rina lowered salinity sufficiently via subsurface freshwater springs to cause bleaching in susceptible species. This suggests the need to monitor not only subsurface sea temperature but also subsurface salinity in localities where freshwater springs occur adjacent to or within coral reefs.
