This study describes the coral communities near Qatarand Abu Dhabi (UAE) ten years after the recurrent elevated temperature anomalies of 1996, 1998 and 2002 which resulted in the mass mortality of Acropora spp. Data d...This study describes the coral communities near Qatarand Abu Dhabi (UAE) ten years after the recurrent elevated temperature anomalies of 1996, 1998 and 2002 which resulted in the mass mortality of Acropora spp. Data derived from photo transects taken over a four-year period were analyzed to characterize the existing coral communities, to compare these to the pre- and post-disturbance communities in the adjacent waters near Dubai, and to project the time-frames required for the communities to return to pre-disturbance levels. The massive corals, dominated by Porites spp. and faviids, showed no long-terms affects associated with exposures to the three thermal anomalies;whereas acroporids, comprising 0% - 8% of the live coral cover, were in various stages of recovery. Projections indicated that acroporid regeneration will require 15 - 32 years to achieve the ≥40% pre-disturbance area cover. The existing communities are too small in size and number to be self-seeding;thus, they are dependent upon the recruitment of larvae from remote refuges of colonies that survived the thermal anomalies. Efforts to identify these refuges and to establish appropriate multi-national conservation programs shall become critical to the future survival of acroporids throughout the southeasternArabian Gulfas the projected regeneration times exceed the periods between disturbances, which are expected to occur more frequently as a result of global climate change.展开更多
Chronic eutrophication and turbidity are critical detrimental factors impacting coral reef ecosystems, adversely affecting their ecological functions, services, benefits, and resilience across multiple spatial scales ...Chronic eutrophication and turbidity are critical detrimental factors impacting coral reef ecosystems, adversely affecting their ecological functions, services, benefits, and resilience across multiple spatial scales and over prolonged periods of time. Inadequate land use practices and lack of appropriate sewage treatment can adversely contribute to increase land-based source pollution (LBSP) impacts in coastal waters and to magnify impacts by sea surface warming trends associated to climate change. Fringing coral reefs off Vega Baja, Puerto Rico, support extensive remnant patches of Elkhorn coral Acropora palmata (Lamarck 1816), which was listed in 2006 as a threatened species under the US Endangered Species Act. Chronic impacts by LBSP have significantly affected local downstream fringing reefs. We characterized the spatial extent of a water quality stress gradient across 12 reefs along the Vega Baja coast through monthly measurements of multiple physico-chemical parameters. Most parameters, particularly PO4, , chlorophyll-a, and the concentration of optical brighteners (OABs), showed a statistically significant increase (PERMANOVA, p < 0.05) in waters close to the main pollution sources, but also in waters adjacent to Cibuco River effluents. Dissolved oxygen also declined and turbidity increased on polluted sites. PO4, , and chlorophyll-a, exceeded recommended concentrations for coral reef ecosystems by factors of 7 - 50 times, 600 - 1240 times, and 17 - 83 times, respectively, depending on the source of the effluents and the distance from sewage pollution sources. Also, water turbidity exceeded 4 - 10 times the recommended value for pristine coral reefs. Coral reefs showed significant decline in close proximity to the polluted zone, showing a significantly different benthic community structure (PERMANOVA, p < 0.0001) dominated by non-reef building taxa (i.e., macroalgae, algal turf) and bare substrate. Percent coral cover and abundance of A. palmata, showed a significant increase with distance. Coral species richness, species diversity index, and the variance in taxonomic distinctness were very low on reef patches adjacent to the polluted zone, increased at a moderate distance with increasing coral cover and co-existence of multiple species, and declined far from the pollution source due to dominance exerted by A. palmata. This study suggests that chronic LBSP resulted in a major decline of one of the largest and most dense remnant stands of A. palmata across the northeastern Caribbean and that nutrient and chlorophyll-a concentrations were unsustainable for coral reefs. This situation requires immediate solution to prevent further damage to these unprecedented resources. It further suggests that chronic LBSP may synergistically magnify sea-surface warming impacts driving corals to an increased state of risk in face of forecasted climate change impacts. Actions to mitigate and adapt to climate change impacts on coral reefs must require a priori controls of LBSP to be effective.展开更多
This study was conducted to investigate the effects of temperature, pH, ammonia nitrogen content and salinity on the bleaching of Acropora millepora and Palythoa sp. This study included two experiments ： Experiment 1...This study was conducted to investigate the effects of temperature, pH, ammonia nitrogen content and salinity on the bleaching of Acropora millepora and Palythoa sp. This study included two experiments ： Experiment 1 was designed to test the effects of different gradients of temperature, pH, ammonia nitrogen con- tent and salinity at a time point （6h） on Palythoa sp. breeding; and Experiment 2 tested the effects of different levels of temperature, pH, ammonia nitrogen con- tent and salinity at three time points （24, 48 and 72h） on A. millepora bleaching. Before the experiments, A. millepora and Palythoa sp. were washed with filtered seawater （0.45 p,m microporous membrane filtration） and then reared in interior seawater aquurium cylinder. The experiments were carried out when the coral ten- tacles extended and the growth condition were good. The results showed that under high temperature （32 -40 ~C ） , both A. millepora and Palythoa sp. showed drastic reactions in the course of time, reflecting considerably significant stress responses. The number of releasing zooxanthellae increased with increase or de- creaseof the pH value （pH 0, 4, 6, 10, 12） over time. Meanwhile, a relatively thick layer of mucus was found on the upper zone of the seawater and the corals started to bleach. As the concentration of ammonia nitrogen （ NH4 , 0 mmool/L） increased in the course of time, the number of zooxanthellae floating on A. millepo- ra and Palythoa sp. had the tendency to rise. When the salinity level were at 15%o and 40%o for A. miUepora and below 34‰ for Palythoa sp. , a considerable number of zuoxanthellae floated out and had rising trend in their number over time at 24 -72 h and 6 h, respectively. In this occasion, the corals stopped growing and started to bleach. In conclusion, it revealed that temperature, pH, ammonia nitrogen content and salinity are the potential impact factors on coral breeding. It is suggested that, as temperature, pH value and salinity decrease or increase, as well as anmlonia nitrogen content rises, the quantity of phycobiont would be raised, and the bleaching would be more severe.展开更多
Diuron is one of the most frequently applied herbicides in sugarcane farming in southern Japan,and Australia.In addition,it is used as a booster substance in copper-based antifouling paints.Due to these various uses,D...Diuron is one of the most frequently applied herbicides in sugarcane farming in southern Japan,and Australia.In addition,it is used as a booster substance in copper-based antifouling paints.Due to these various uses,Diuron is released into the marine environment;however,little information is available on gene expression in corals and their symbiotic algae exposed to Diuron.We investigated the efects of Diuron on stress-responsive gene expression in the hermatypic coral Acropora tenuis and its symbiotic dinofagellates.After seven days of exposure to 1µg/L and 10µg/L Diuron,no signifcant changes in the body colour of corals were observed.However,quantitative reverse transcription-polymerase chain reaction analyses revealed that the expression levels of stress-responsive genes,such as heat shock protein 90(HSP90),HSP70,and calreticulin(CALR),were signifcantly downregulated in corals exposed to 10µg/L of Diuron for seven days.Moreover,aquaglyceroporin was signifcantly downregulated in corals exposed to environmentally relevant concentrations of 1µg/L Diuron.In contrast,no such efects were observed on the expression levels of other stress-responsive genes,such as oxidative stress-responsive proteins,methionine adenosyltransferase,and green/red fuorescent proteins.Diuron exposure had no signifcant efect on the expression levels of HSP90,HSP70,or HSP40 in the symbiotic dinofagellates.These results suggest that stress-responsive genes,such as HSPs,respond diferently to Diuron in corals and their symbiotic dinofagellates and that A.tenuis HSPs and CALRs may be useful molecular biomarkers for predicting stress responses induced by the herbicide Diuron.展开更多
Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the r...Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the restoration.We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artifi cial reefs(ARs)from October 2014 to September 2018 during which there were several attacks of typhoons.Results show that two staghorn Acropora species had the highest growth rates(11.0–12.1 cm/a),followed by table coral A.divaricate(5.6 cm/a)and P.damicornis(4.8 cm/a).A linear growth pattern was found for the three Acropora species;the pattern gradually slowed in P.damicornis.There was a strong interspecifi c competition for space among the corals on ARs,and it led to the sharply declined occurrence of slow-growing P.darmicornis colonies in 2017.Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity.However,the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon.Therefore,concrete and environmentalfriendly materials should be used in future restoration.This study is the fi rst report on long-term monitoring and assessment of coral reef restoration in China.The results off er future guide of reef restoration for impaired coral reefs in regions easily aff ected by typhoons.展开更多
Coral reef restoration approaches have often utilized adult colonies as sources for fragments (i.e. clones) to be transplanted. Although restoration through this method is fast and cheap, it has been pointed out that ...Coral reef restoration approaches have often utilized adult colonies as sources for fragments (i.e. clones) to be transplanted. Although restoration through this method is fast and cheap, it has been pointed out that it may reduce genetic diversity of the restored population. Low genetic diversity is a concern for reef restoration when seed fragments are raised asexually from only a few donor colonies. This can lead to lower fertilization rates among seed fragments, and reducing the longterm benefits of reef restoration in particular areas. Additionally, low genetic diversity can compound the effects of increased ocean temperature and other environmental stressors, further jeopardizing the health of a reef. An alternative approach through sexually propagated coral cultures and out-plantings can alleviate this problem. Sexually produced offsprings are more genetically diverse. They can be produced in far greater numbers than coral fragments and do not imply destructive methods. Ongoing research at the Akajima Marine Science Laboratory in Okinawa, Japan has helped to improve the production and maintenance of sexually propagated larval cultures. Our results show that crosses between gametes from 6 or more colonies will provide the highest fertilization rate (>95%). Based on the results, we suggest the use of 6 or more donor colonies for practical gamete fertilization in sexually derived coral culture.展开更多
文摘This study describes the coral communities near Qatarand Abu Dhabi (UAE) ten years after the recurrent elevated temperature anomalies of 1996, 1998 and 2002 which resulted in the mass mortality of Acropora spp. Data derived from photo transects taken over a four-year period were analyzed to characterize the existing coral communities, to compare these to the pre- and post-disturbance communities in the adjacent waters near Dubai, and to project the time-frames required for the communities to return to pre-disturbance levels. The massive corals, dominated by Porites spp. and faviids, showed no long-terms affects associated with exposures to the three thermal anomalies;whereas acroporids, comprising 0% - 8% of the live coral cover, were in various stages of recovery. Projections indicated that acroporid regeneration will require 15 - 32 years to achieve the ≥40% pre-disturbance area cover. The existing communities are too small in size and number to be self-seeding;thus, they are dependent upon the recruitment of larvae from remote refuges of colonies that survived the thermal anomalies. Efforts to identify these refuges and to establish appropriate multi-national conservation programs shall become critical to the future survival of acroporids throughout the southeasternArabian Gulfas the projected regeneration times exceed the periods between disturbances, which are expected to occur more frequently as a result of global climate change.
文摘Chronic eutrophication and turbidity are critical detrimental factors impacting coral reef ecosystems, adversely affecting their ecological functions, services, benefits, and resilience across multiple spatial scales and over prolonged periods of time. Inadequate land use practices and lack of appropriate sewage treatment can adversely contribute to increase land-based source pollution (LBSP) impacts in coastal waters and to magnify impacts by sea surface warming trends associated to climate change. Fringing coral reefs off Vega Baja, Puerto Rico, support extensive remnant patches of Elkhorn coral Acropora palmata (Lamarck 1816), which was listed in 2006 as a threatened species under the US Endangered Species Act. Chronic impacts by LBSP have significantly affected local downstream fringing reefs. We characterized the spatial extent of a water quality stress gradient across 12 reefs along the Vega Baja coast through monthly measurements of multiple physico-chemical parameters. Most parameters, particularly PO4, , chlorophyll-a, and the concentration of optical brighteners (OABs), showed a statistically significant increase (PERMANOVA, p < 0.05) in waters close to the main pollution sources, but also in waters adjacent to Cibuco River effluents. Dissolved oxygen also declined and turbidity increased on polluted sites. PO4, , and chlorophyll-a, exceeded recommended concentrations for coral reef ecosystems by factors of 7 - 50 times, 600 - 1240 times, and 17 - 83 times, respectively, depending on the source of the effluents and the distance from sewage pollution sources. Also, water turbidity exceeded 4 - 10 times the recommended value for pristine coral reefs. Coral reefs showed significant decline in close proximity to the polluted zone, showing a significantly different benthic community structure (PERMANOVA, p < 0.0001) dominated by non-reef building taxa (i.e., macroalgae, algal turf) and bare substrate. Percent coral cover and abundance of A. palmata, showed a significant increase with distance. Coral species richness, species diversity index, and the variance in taxonomic distinctness were very low on reef patches adjacent to the polluted zone, increased at a moderate distance with increasing coral cover and co-existence of multiple species, and declined far from the pollution source due to dominance exerted by A. palmata. This study suggests that chronic LBSP resulted in a major decline of one of the largest and most dense remnant stands of A. palmata across the northeastern Caribbean and that nutrient and chlorophyll-a concentrations were unsustainable for coral reefs. This situation requires immediate solution to prevent further damage to these unprecedented resources. It further suggests that chronic LBSP may synergistically magnify sea-surface warming impacts driving corals to an increased state of risk in face of forecasted climate change impacts. Actions to mitigate and adapt to climate change impacts on coral reefs must require a priori controls of LBSP to be effective.
基金Supported by Major Science and Technology Projects in Hainan Province from Science and Technology Department of Hainan Province Government,China(ZDKJ2016013ZDKJ2016009)+1 种基金Hainan Key laboratory for Conservation and Utilization of Tropical Marine Fishery ResourcesKey Laboratory of Seawater Aquaculture Research of Sanya City(L1507)
文摘This study was conducted to investigate the effects of temperature, pH, ammonia nitrogen content and salinity on the bleaching of Acropora millepora and Palythoa sp. This study included two experiments ： Experiment 1 was designed to test the effects of different gradients of temperature, pH, ammonia nitrogen con- tent and salinity at a time point （6h） on Palythoa sp. breeding; and Experiment 2 tested the effects of different levels of temperature, pH, ammonia nitrogen con- tent and salinity at three time points （24, 48 and 72h） on A. millepora bleaching. Before the experiments, A. millepora and Palythoa sp. were washed with filtered seawater （0.45 p,m microporous membrane filtration） and then reared in interior seawater aquurium cylinder. The experiments were carried out when the coral ten- tacles extended and the growth condition were good. The results showed that under high temperature （32 -40 ~C ） , both A. millepora and Palythoa sp. showed drastic reactions in the course of time, reflecting considerably significant stress responses. The number of releasing zooxanthellae increased with increase or de- creaseof the pH value （pH 0, 4, 6, 10, 12） over time. Meanwhile, a relatively thick layer of mucus was found on the upper zone of the seawater and the corals started to bleach. As the concentration of ammonia nitrogen （ NH4 , 0 mmool/L） increased in the course of time, the number of zooxanthellae floating on A. millepo- ra and Palythoa sp. had the tendency to rise. When the salinity level were at 15%o and 40%o for A. miUepora and below 34‰ for Palythoa sp. , a considerable number of zuoxanthellae floated out and had rising trend in their number over time at 24 -72 h and 6 h, respectively. In this occasion, the corals stopped growing and started to bleach. In conclusion, it revealed that temperature, pH, ammonia nitrogen content and salinity are the potential impact factors on coral breeding. It is suggested that, as temperature, pH value and salinity decrease or increase, as well as anmlonia nitrogen content rises, the quantity of phycobiont would be raised, and the bleaching would be more severe.
基金This work was supported by the Japan Society for the Promotion of Science(JSPS)Grants-in-Aid for Scientifc Research(KAKENHI)(Grant Nos.26281048 and 21H03619).
文摘Diuron is one of the most frequently applied herbicides in sugarcane farming in southern Japan,and Australia.In addition,it is used as a booster substance in copper-based antifouling paints.Due to these various uses,Diuron is released into the marine environment;however,little information is available on gene expression in corals and their symbiotic algae exposed to Diuron.We investigated the efects of Diuron on stress-responsive gene expression in the hermatypic coral Acropora tenuis and its symbiotic dinofagellates.After seven days of exposure to 1µg/L and 10µg/L Diuron,no signifcant changes in the body colour of corals were observed.However,quantitative reverse transcription-polymerase chain reaction analyses revealed that the expression levels of stress-responsive genes,such as heat shock protein 90(HSP90),HSP70,and calreticulin(CALR),were signifcantly downregulated in corals exposed to 10µg/L of Diuron for seven days.Moreover,aquaglyceroporin was signifcantly downregulated in corals exposed to environmentally relevant concentrations of 1µg/L Diuron.In contrast,no such efects were observed on the expression levels of other stress-responsive genes,such as oxidative stress-responsive proteins,methionine adenosyltransferase,and green/red fuorescent proteins.Diuron exposure had no signifcant efect on the expression levels of HSP90,HSP70,or HSP40 in the symbiotic dinofagellates.These results suggest that stress-responsive genes,such as HSPs,respond diferently to Diuron in corals and their symbiotic dinofagellates and that A.tenuis HSPs and CALRs may be useful molecular biomarkers for predicting stress responses induced by the herbicide Diuron.
基金Supported by the National Key R&D Program of China(No.2018YFC1406503),the Scientifi c Research Foundation of Third Institutes of Oceanography“Fujian Provincial Station for Field Observation and Research of Island and Coastal Zone in Zhangzhou”(No.TIO 2019017)the National Natural Science Foundation of China(No.41976127)the China-ASEAN Maritime Cooperation Fund Project“Monitoring and Conservation of coastal ecosystems in the South China Sea”and“China-ASEAN Countries Collaboration on Marine Endangered Species Researches(MESR)”。
文摘Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the restoration.We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artifi cial reefs(ARs)from October 2014 to September 2018 during which there were several attacks of typhoons.Results show that two staghorn Acropora species had the highest growth rates(11.0–12.1 cm/a),followed by table coral A.divaricate(5.6 cm/a)and P.damicornis(4.8 cm/a).A linear growth pattern was found for the three Acropora species;the pattern gradually slowed in P.damicornis.There was a strong interspecifi c competition for space among the corals on ARs,and it led to the sharply declined occurrence of slow-growing P.darmicornis colonies in 2017.Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity.However,the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon.Therefore,concrete and environmentalfriendly materials should be used in future restoration.This study is the fi rst report on long-term monitoring and assessment of coral reef restoration in China.The results off er future guide of reef restoration for impaired coral reefs in regions easily aff ected by typhoons.
文摘Coral reef restoration approaches have often utilized adult colonies as sources for fragments (i.e. clones) to be transplanted. Although restoration through this method is fast and cheap, it has been pointed out that it may reduce genetic diversity of the restored population. Low genetic diversity is a concern for reef restoration when seed fragments are raised asexually from only a few donor colonies. This can lead to lower fertilization rates among seed fragments, and reducing the longterm benefits of reef restoration in particular areas. Additionally, low genetic diversity can compound the effects of increased ocean temperature and other environmental stressors, further jeopardizing the health of a reef. An alternative approach through sexually propagated coral cultures and out-plantings can alleviate this problem. Sexually produced offsprings are more genetically diverse. They can be produced in far greater numbers than coral fragments and do not imply destructive methods. Ongoing research at the Akajima Marine Science Laboratory in Okinawa, Japan has helped to improve the production and maintenance of sexually propagated larval cultures. Our results show that crosses between gametes from 6 or more colonies will provide the highest fertilization rate (>95%). Based on the results, we suggest the use of 6 or more donor colonies for practical gamete fertilization in sexually derived coral culture.
