The mechanisms by which oligotrophic and eutrophic lakes rid itself of Escherichia coli or faecal coliforms are still not clearly understood. This study sought to review the various means by which E. coli or faecal co...The mechanisms by which oligotrophic and eutrophic lakes rid itself of Escherichia coli or faecal coliforms are still not clearly understood. This study sought to review the various means by which E. coli or faecal coliforms are inactivated or removed in lakes. The review cited temperature, solar radiation, predation, starvation, attachment and sedimentation as key factors that aid the removal of E. coli in lakes. In eutrophic lakes additional factors such as the role of algal biomass may play a role due to increased pH and dissolved oxygen levels attributed to algal presence. Algal toxins or exudates may also play a role although this is still under debate. The interactive effect of two or more of these factors on E. coli inactivation and the relative importance of these mechanisms on E. coli removal are still not known. Areas for further research include the role of algae in sedimenting E. coli or faecal coliforms and the possible role of algal exudates on E. coli inactivation.展开更多
Black band disease （BBD）, characterized by the Cyanobacterial dominated pathogenic consortium, is thought to play a key role in the global decline of the coral reef ecosystems. The present paper originally documents...Black band disease （BBD）, characterized by the Cyanobacterial dominated pathogenic consortium, is thought to play a key role in the global decline of the coral reef ecosystems. The present paper originally documents a case of BBD from Yongxing Island （Xisha Islands, South China Sea）, and further probes the reasons of this abnormal phenomenon. Prior to 2007, corals at northern reef-flat of Yongxing Isand were in healthy growth. Catastrophic coral mortality occurred between 2007 and 2008. The 16S rRNA gene sequencing and PCR amplification, with universally conserved primers, were applied to detect the conta- gious bacterial community of the microbial mat. The results demonstrated that six bacterial divisions constituted the clone libraries derived from the BBD mat, and that Cyanobacteria are the most diversely represented group that inhabit BBD bacteri- al mats, despite the fact that species in five others divisions （a-Proteobacteria, y-Proteobacteria, Bacteroidetes, Verrucomi- crobia and Actinobacteria） are also consistently diverse within the BBD mats of diseased coral. Other factors such as coral bleaching, typhoons, ocean acidification and crown-of-thorns starfish outbreaks, are not primarily responsible for the coral mortality within such a short time interval. The disaster expansion of BBD associated with Cyanobacterial blooms is a more likely mechanism impacting these coral reefs. Excessive human activity enhances the eutrophication of the marine water of the reefal region and may result in occurrence of the BBD.展开更多
文摘The mechanisms by which oligotrophic and eutrophic lakes rid itself of Escherichia coli or faecal coliforms are still not clearly understood. This study sought to review the various means by which E. coli or faecal coliforms are inactivated or removed in lakes. The review cited temperature, solar radiation, predation, starvation, attachment and sedimentation as key factors that aid the removal of E. coli in lakes. In eutrophic lakes additional factors such as the role of algal biomass may play a role due to increased pH and dissolved oxygen levels attributed to algal presence. Algal toxins or exudates may also play a role although this is still under debate. The interactive effect of two or more of these factors on E. coli inactivation and the relative importance of these mechanisms on E. coli removal are still not known. Areas for further research include the role of algae in sedimenting E. coli or faecal coliforms and the possible role of algal exudates on E. coli inactivation.
基金supported by National Natural Science Foundation of China(Grant Nos.40976030&41006029)Project of International Cooperation and Exchanges NSFC(Grant No.41210104029)Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.SQ201114)
文摘Black band disease （BBD）, characterized by the Cyanobacterial dominated pathogenic consortium, is thought to play a key role in the global decline of the coral reef ecosystems. The present paper originally documents a case of BBD from Yongxing Island （Xisha Islands, South China Sea）, and further probes the reasons of this abnormal phenomenon. Prior to 2007, corals at northern reef-flat of Yongxing Isand were in healthy growth. Catastrophic coral mortality occurred between 2007 and 2008. The 16S rRNA gene sequencing and PCR amplification, with universally conserved primers, were applied to detect the conta- gious bacterial community of the microbial mat. The results demonstrated that six bacterial divisions constituted the clone libraries derived from the BBD mat, and that Cyanobacteria are the most diversely represented group that inhabit BBD bacteri- al mats, despite the fact that species in five others divisions （a-Proteobacteria, y-Proteobacteria, Bacteroidetes, Verrucomi- crobia and Actinobacteria） are also consistently diverse within the BBD mats of diseased coral. Other factors such as coral bleaching, typhoons, ocean acidification and crown-of-thorns starfish outbreaks, are not primarily responsible for the coral mortality within such a short time interval. The disaster expansion of BBD associated with Cyanobacterial blooms is a more likely mechanism impacting these coral reefs. Excessive human activity enhances the eutrophication of the marine water of the reefal region and may result in occurrence of the BBD.
