Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status an...Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.展开更多
Coral transplantation is considered as one of the major tools to increase coral abundance for degraded coral reefs.To investigate the effects of various methods and coral species in transplantation,coral fragments(n=9...Coral transplantation is considered as one of the major tools to increase coral abundance for degraded coral reefs.To investigate the effects of various methods and coral species in transplantation,coral fragments(n=902)of five coral species were transplanted by four methods at Luhuitou,the Sanya Bay,Hainan Province,China,where the reef has been over-exploited and is still threatened by human activities and natural disasters.Ten months after the transplant,the average survivorship of the transplanted corals was 45.5%.Methodologies had different effects on the transplanted corals,but none of them was efficacious for all coral species.Methodology could not change the decreasing trend for Montipora foliosa and Acropora hyacinthus,although it did slow down their decline.All transplants of A.hyacinthus and M.foliosa had high mortalities and significant decrease on survival area,while Porites andrewsi and Galaxea fascicularis had lower mortalities and partial mortalities.Only one method had significant effect on increasing survival area of G.fascicularis,same as P.andrewsi.Out of the five transplanted coral species,Pocillopora damicornis was the only species that had living tissue area increase in all applied methods,while the others had decreased live tissue area in one or more methods.The results of this study suggested that performing coral transplantation in a highly threatened area was not efficient unless the threats were diminished or erased.Moreover,proper species selection for coral transplantation is crucial,especially in a disturbed environment.Methodology,although having limited effects on improving results of coral transplantation,cannot compensate the maladjustment of vulnerable species to the stresses on the Luhuitou Reef.Coral transplantation on Luhuitou Reef should not be performed unless the stresses are under controlled,and corals with good tolerance to the environment should be considered first.展开更多
基金Supported by the National Key Research and Development Program of China(Nos.2021YFC3100500,2022YFC3103602,2021YFF0502800)the National Natural Science Foundation of China(No.U23A2035)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2023B1212060047)the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences(No.LTO1919)the Visiting Fellowship Program of the State Key Laboratory of Marine Environmental Science,Xiamen University(No.MELRS1914)the Hainan Province Key R&D Program(No.ZDYF2023SHFZ131)。
文摘Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.
基金The Key Technology Project of Hainan under contract No.ZDZX2013014-3the Ocean Public Welfare Scientific Research Project under contract Nos 201105012-2 and 201305030-3the National Natural Science Foundation of China(NSFC)under contract Nos41206140 and 41306144
文摘Coral transplantation is considered as one of the major tools to increase coral abundance for degraded coral reefs.To investigate the effects of various methods and coral species in transplantation,coral fragments(n=902)of five coral species were transplanted by four methods at Luhuitou,the Sanya Bay,Hainan Province,China,where the reef has been over-exploited and is still threatened by human activities and natural disasters.Ten months after the transplant,the average survivorship of the transplanted corals was 45.5%.Methodologies had different effects on the transplanted corals,but none of them was efficacious for all coral species.Methodology could not change the decreasing trend for Montipora foliosa and Acropora hyacinthus,although it did slow down their decline.All transplants of A.hyacinthus and M.foliosa had high mortalities and significant decrease on survival area,while Porites andrewsi and Galaxea fascicularis had lower mortalities and partial mortalities.Only one method had significant effect on increasing survival area of G.fascicularis,same as P.andrewsi.Out of the five transplanted coral species,Pocillopora damicornis was the only species that had living tissue area increase in all applied methods,while the others had decreased live tissue area in one or more methods.The results of this study suggested that performing coral transplantation in a highly threatened area was not efficient unless the threats were diminished or erased.Moreover,proper species selection for coral transplantation is crucial,especially in a disturbed environment.Methodology,although having limited effects on improving results of coral transplantation,cannot compensate the maladjustment of vulnerable species to the stresses on the Luhuitou Reef.Coral transplantation on Luhuitou Reef should not be performed unless the stresses are under controlled,and corals with good tolerance to the environment should be considered first.
