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Michael E Field - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of the impact of sea level rise on Fringing coral Reef hydrodynamics and sediment transport
Coral Reefs, 2011Co-Authors: Curt D Storlazzi, Michael E Field, Edwin Elias, M K PrestoAbstract:Most climate projections suggest that sea level may rise on the order of 0.5-1.0 m by 2100; it is not clear, however, how fluid flow and sediment dynamics on exposed Fringing Reefs might change in response to this rapid sea-level rise. Coupled hydrodynamic and sediment- transport numerical modeling is consistent with recent published results that suggest that an increase in water depth on the order of 0.5-1.0 m on a 1-2 m deep exposed Fringing Reef flat would result in larger significant wave heights and setup, further elevating water depths on the Reef flat. Larger waves would generate higher near-bed shear stresses, which, in turn, would result in an increase in both the size and the quantity of sediment that can be resuspended from the seabed or eroded from adjacent coastal plain deposits. Greater wave- and wind-driven currents would develop with increasing water depth, increasing the alongshore and offshore flux of water and sediment from the inner Reef flat to the outer Reef flat and fore Reef where coral growth is typically greatest. Sediment residence time on the Fringing Reef flat was modeled to decrease exponentially with increasing sea-level rise as the magnitude of sea-level rise approached the mean water depth over the Reef flat. The model results presented here suggest that a 0.5-1.0 m rise in sea level will likely increase coastal erosion, mixing and circulation, the amount of sediment resuspended, and the duration of high turbidity on exposed Reef flats, resulting in decreased light availability for photosynthesis, increased sediment-induced stress on the Reef ecosystem, and potentially affecting a number of other ecological processes.
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coral ba ca records of sediment input to the Fringing Reef of the southshore of moloka i hawai i over the last several decades
Marine Pollution Bulletin, 2010Co-Authors: Nancy G Prouty, Michael E Field, J D Stock, Stacy D Jupiter, Malcolm T MccullochAbstract:The Fringing Reef of southern Moloka'i is perceived to be in decline because of land-based pollution. In the absence of historical records of sediment pollution, ratios of coral Ba/Ca were used to test the hypothesis that sedimentation has increased over time. Baseline Ba/Ca ratios co-vary with the abundance of red, terrigenous sediment visible in recent imagery. The highest values at One Ali'i are near one of the muddiest parts of the Reef. This co-varies with the lowest growth rate of all the sites, perhaps because the upstream Kawela watershed was historically leveed all the way to the nearshore, providing a fast-path for sediment delivery. Sites adjacent to small, steep watersheds have ∼decadal periodicities whereas sites adjacent to mangrove forests have shorter-period fluctuations that correspond to the periodicity of sediment transport in the nearshore, rather than the watershed. All four sites show a statistically significant upward trend in Ba/Ca.
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temporal and spatial variability in the flow and dispersal of suspended sediment on a Fringing Reef flat molokai hawaii
Estuarine Coastal and Shelf Science, 2006Co-Authors: M K Presto, Andrea S Ogston, Curt D Storlazzi, Michael E FieldAbstract:Abstract A multi-year study was conducted on a shallow Fringing Reef flat on Molokai, Hawaii to determine the temporal and spatial dispersal patterns of terrigenous suspended sediment. During this study, trade-wind conditions existed for the majority of the year on the Reef flat. The trade-wind conditions produced strong currents and resuspended moderate amounts of sediment on the Reef flat on a daily basis during the year of study, resulting in an overwhelming contribution to the total sediment flux. The magnitude and direction of the trade winds relative to the orientation of the coastline, the shallow-relief and broad morphology, and tidal elevation, provided the primary control of the physical processes that resuspended and transported sediment on the Reef flat over the period of record. Spatial data indicate that much of the terrigenous sediment resuspended on the Reef flat is transported predominantly alongshore and is confined to the inner- to mid-Reef flat. Evidence for the limited across-shore mixing and transport is provided by the dominantly alongshore wind-driven currents during trade-wind conditions and the well-defined across-shore gradient in percentage calcium carbonate of the suspended sediment. Regions of slightly offshore suspended-sediment transport along the Reef flat can be attributed to the circulation pattern set up by the interaction between the trade winds, coastal morphology, and anthropogenic coastal structures (i.e., fish ponds and wharf). The regions in which sediment were seen to move offshore provide the strongest link between the sediment dynamics on Reef flat and fore Reef, and qualitatively appears to be correlated with low coral coverage on the fore Reef.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance. These results have application to Reef studies and Reef management in other areas in several ways. First, the observed resuspension and turbidity results from fine-grained terrigenous sediment that appears to be trapped and recycled on the Reef flat. Thus corals are subjected to light attenuation by the same particles repeatedly, however small the amount. Secondly, the measurements show high temporal variability (from daily to seasonal scales) of sediment resuspension, indicating that single measurements are inadequate to accurately describe conditions on a Reef flat.
M K Presto - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of the impact of sea level rise on Fringing coral Reef hydrodynamics and sediment transport
Coral Reefs, 2011Co-Authors: Curt D Storlazzi, Michael E Field, Edwin Elias, M K PrestoAbstract:Most climate projections suggest that sea level may rise on the order of 0.5-1.0 m by 2100; it is not clear, however, how fluid flow and sediment dynamics on exposed Fringing Reefs might change in response to this rapid sea-level rise. Coupled hydrodynamic and sediment- transport numerical modeling is consistent with recent published results that suggest that an increase in water depth on the order of 0.5-1.0 m on a 1-2 m deep exposed Fringing Reef flat would result in larger significant wave heights and setup, further elevating water depths on the Reef flat. Larger waves would generate higher near-bed shear stresses, which, in turn, would result in an increase in both the size and the quantity of sediment that can be resuspended from the seabed or eroded from adjacent coastal plain deposits. Greater wave- and wind-driven currents would develop with increasing water depth, increasing the alongshore and offshore flux of water and sediment from the inner Reef flat to the outer Reef flat and fore Reef where coral growth is typically greatest. Sediment residence time on the Fringing Reef flat was modeled to decrease exponentially with increasing sea-level rise as the magnitude of sea-level rise approached the mean water depth over the Reef flat. The model results presented here suggest that a 0.5-1.0 m rise in sea level will likely increase coastal erosion, mixing and circulation, the amount of sediment resuspended, and the duration of high turbidity on exposed Reef flats, resulting in decreased light availability for photosynthesis, increased sediment-induced stress on the Reef ecosystem, and potentially affecting a number of other ecological processes.
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temporal and spatial variability in the flow and dispersal of suspended sediment on a Fringing Reef flat molokai hawaii
Estuarine Coastal and Shelf Science, 2006Co-Authors: M K Presto, Andrea S Ogston, Curt D Storlazzi, Michael E FieldAbstract:Abstract A multi-year study was conducted on a shallow Fringing Reef flat on Molokai, Hawaii to determine the temporal and spatial dispersal patterns of terrigenous suspended sediment. During this study, trade-wind conditions existed for the majority of the year on the Reef flat. The trade-wind conditions produced strong currents and resuspended moderate amounts of sediment on the Reef flat on a daily basis during the year of study, resulting in an overwhelming contribution to the total sediment flux. The magnitude and direction of the trade winds relative to the orientation of the coastline, the shallow-relief and broad morphology, and tidal elevation, provided the primary control of the physical processes that resuspended and transported sediment on the Reef flat over the period of record. Spatial data indicate that much of the terrigenous sediment resuspended on the Reef flat is transported predominantly alongshore and is confined to the inner- to mid-Reef flat. Evidence for the limited across-shore mixing and transport is provided by the dominantly alongshore wind-driven currents during trade-wind conditions and the well-defined across-shore gradient in percentage calcium carbonate of the suspended sediment. Regions of slightly offshore suspended-sediment transport along the Reef flat can be attributed to the circulation pattern set up by the interaction between the trade winds, coastal morphology, and anthropogenic coastal structures (i.e., fish ponds and wharf). The regions in which sediment were seen to move offshore provide the strongest link between the sediment dynamics on Reef flat and fore Reef, and qualitatively appears to be correlated with low coral coverage on the fore Reef.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance. These results have application to Reef studies and Reef management in other areas in several ways. First, the observed resuspension and turbidity results from fine-grained terrigenous sediment that appears to be trapped and recycled on the Reef flat. Thus corals are subjected to light attenuation by the same particles repeatedly, however small the amount. Secondly, the measurements show high temporal variability (from daily to seasonal scales) of sediment resuspension, indicating that single measurements are inadequate to accurately describe conditions on a Reef flat.
Qi Shi - One of the best experts on this subject based on the ideXlab platform.
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interseasonal and interspecies diversities of symbiodinium density and effective photochemical efficiency in five dominant Reef coral species from luhuitou Fringing Reef northern south china sea
Coral Reefs, 2017Co-Authors: Guohui Liu, Qi Shi, Tianran Chen, Shichen Tao, Huiling ZhangAbstract:Although it is well established that different coral species have different susceptibilities to thermal stress, the reasons behind this variation are still unclear. In this study, 384 samples across five dominant coral species were collected seasonally between September 2013 and August 2014 at Luhuitou Fringing Reef in Sanya, Hainan Island, northern South China Sea, and their algal symbiont density and effective photochemical efficiency (Φ PSII) were measured. The results indicated that both the Symbiodinium density and Φ PSII of corals were subject to significant interspecies and seasonal variations. Stress-tolerant coral species, including massive Porites lutea and plating Pavona decussata, had higher symbiont densities but lower Φ PSII compared to the vulnerable branching species of Acropora over the course of all four seasons. Seasonally, coral symbiont densities were the lowest during winter, while during the same period, Φ PSII of corals was at the highest point. Further analysis suggested that dissolved inorganic nutrients and upwelling in the Reef area were probably responsible for the observed seasonal variations in symbiont density. The fact that Porites lutea has the lowest Φ PSII during all four seasons is likely related to their symbionts’ lower capacity to provide required photosynthates for calcification. These results suggest that a coral’s thermal tolerance is primarily and positively dependent on its symbiont density and is less related to its effective photochemical efficiency.
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seasonal variations of seawater pco2 and sea air co2 fluxes in a Fringing coral Reef northern south china sea
Journal of Geophysical Research, 2016Co-Authors: Hongqiang Yan, Meixia Zhao, Qi Shi, Tianran Chen, Guohui Liu, Yehui Tan, Yinghui WangAbstract:Evidence based on four field surveys conducted between July 2009 and April 2011 indicates that both sea surface partial pressures of CO2 (pCO(2)) and sea-air CO2 fluxes at Luhuitou Fringing Reef in Sanya, Hainan Island, northern South China Sea (SCS) are subject to significant seasonal variations. The diurnal variation of seawater pCO(2) ranges from 264 to 579 mu atm in summer, which is much larger than that in autumn (152-335 mu atm), in winter (84-260 mu atm), and in spring (114-228 mu atm). The sea-air CO2 flux in summer (similar to 9.6 mmol CO2 m(-2) d(-1)) is also larger than that in other seasons (i.e.,similar to 3 mmol CO2 m(-2) d(-1) in spring, similar to 3.5 mmol CO2 m(-2) d(-1) in autumn, and similar to 2.7 mmol CO2 m(-2) d(-1) in winter). The atmospheric pCO(2) in this Reef shows small diurnal and seasonal variations. The integration of the time-series pCO(2) data shows that the Reef area is a weak source of atmospheric CO2 at similar to 0.54 mol CO2 m(-2) yr(-1). Further analyses indicate that the seasonal variations of the surface seawater pCO(2) in Luhuitou Fringing Reef are mainly affected by seasonally-dependent biological metabolic processes (organic processe and inorganic process), and that the organic process play a more important role than the inorganic process. Seasonal sea surface temperature (SST) variations and hydrodynamic processes may also have some influence on seawater pCO(2) variation.
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age structure of massive porites lutea corals at luhuitou Fringing Reef northern south china sea indicates recovery following severe anthropogenic disturbance
Coral Reefs, 2014Co-Authors: Meixia Zhao, Q M Zhang, Qi Shi, George RoffAbstract:Luhuitou Fringing Reef at Hainan Island (northern South China Sea) has experienced severe anthropogenic disturbance, with live coral cover declining by > 80 % since the 1960 s. To assess the size structure of Porites lutea, we measured the sizes of 1,857 colonies from the Reef flat (0 m) and slope (2–4 m depth). Both populations were positively skewed and leptokurtic in shape, indicating a high abundance of smaller colonies (averaging 21.4 ± 2.3 cm on the flat and 31.9 ± 2.8 cm on the slope). Age structure of populations was determined through growth rates extracted from X-rays of P. lutea cores. The majority of colonies (> 95 %) were < 50 yr old, with 55 % of P. lutea on the Reef flat having recruited following the establishment of a marine reserve in 1990. The abundance of younger colonies indicates significant recovery of P. lutea following the removal of chronic anthropogenic disturbance.
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estimate of carbonate production by scleractinian corals at luhuitou Fringing Reef sanya china
Chinese Science Bulletin, 2009Co-Authors: Qi Shi, Meixia Zhao, Qiaomin Zhang, Tianran Chen, Hankui WangAbstract:Carbonate production by scleractinian corals not only maintains coral Reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scleractinian corals at Luhuitou Fringing Reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 +/- 0.55 kg center dot m(-2) center dot a(-1) and 3.52 +/- 1.32 kg center dot m(-2) center dot a(-1) on the Reef flat and Reef slope, respectively, depending on the composition and distribution of corals and the intergeneric difference of skeletal growth. In response to the rapidly increasing human impacts, coral carbonate production has decreased by 80%-89% at this Fringing Reef since the 1960s; as a result, the Reef accretion rate declined and became lower than the rate of sea level rise. Further development of the Luhuitou Fringing Reef will switch significantly from lateral extension seawards to vertical growth, reflecting a response of coral Reef bio-geomorphic process to strong human impacts under the background of global sea level rise. In addition, decrease in coral carbonate production reduced CO2 release from this Fringing Reef. In the future, it is likely that the role played by coral Reefs, especially of Fringing Reefs, in the ocean and even in the global carbon cycle will be modified or weakened by the increasing human impacts.
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status monitoring and health assessment of luhuitou Fringing Reef of sanya hainan china
Chinese Science Bulletin, 2006Co-Authors: Qiaomin Zhang, Qi Shi, Hankui Wang, Gang Chen, T C W Fong, D C C Wong, Hui Huang, Meixia ZhaoAbstract:The monitoring survey and health assessment for benthic community were carried out in Luhuitou Fringing Reef of Sanya, Hainan, China in 2002. Monitoring survey included manta tow, line intercept transect, video transect and digital photograph. The mean live coral cover was 23.40%. Comparison of used monitoring methods showed that video transect can replace line intercept transect, and 50 m transect is better than 20 m transect in uneven coral region. Survey data and comparison with previous research work showed that Luhuitou Fringing Reef has been damaged severely and has a general declining trend with live coral cover from about 85% in the 1960s down to 20% in 2004, but it still has quite high biodiversity and therefore has special protection value. Main factors of Luhuitou Fringing Reef declining were human activities including Reef rock digging and curios collecting, destructive fishing, sediment and pollutant from coastal land, and recent marine aquaculture. Only strengthening integrated management can reach improvement and restoration of Luhuitou declining coral Reef ecosystem.
Curt D Storlazzi - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of the impact of sea level rise on Fringing coral Reef hydrodynamics and sediment transport
Coral Reefs, 2011Co-Authors: Curt D Storlazzi, Michael E Field, Edwin Elias, M K PrestoAbstract:Most climate projections suggest that sea level may rise on the order of 0.5-1.0 m by 2100; it is not clear, however, how fluid flow and sediment dynamics on exposed Fringing Reefs might change in response to this rapid sea-level rise. Coupled hydrodynamic and sediment- transport numerical modeling is consistent with recent published results that suggest that an increase in water depth on the order of 0.5-1.0 m on a 1-2 m deep exposed Fringing Reef flat would result in larger significant wave heights and setup, further elevating water depths on the Reef flat. Larger waves would generate higher near-bed shear stresses, which, in turn, would result in an increase in both the size and the quantity of sediment that can be resuspended from the seabed or eroded from adjacent coastal plain deposits. Greater wave- and wind-driven currents would develop with increasing water depth, increasing the alongshore and offshore flux of water and sediment from the inner Reef flat to the outer Reef flat and fore Reef where coral growth is typically greatest. Sediment residence time on the Fringing Reef flat was modeled to decrease exponentially with increasing sea-level rise as the magnitude of sea-level rise approached the mean water depth over the Reef flat. The model results presented here suggest that a 0.5-1.0 m rise in sea level will likely increase coastal erosion, mixing and circulation, the amount of sediment resuspended, and the duration of high turbidity on exposed Reef flats, resulting in decreased light availability for photosynthesis, increased sediment-induced stress on the Reef ecosystem, and potentially affecting a number of other ecological processes.
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temporal and spatial variability in the flow and dispersal of suspended sediment on a Fringing Reef flat molokai hawaii
Estuarine Coastal and Shelf Science, 2006Co-Authors: M K Presto, Andrea S Ogston, Curt D Storlazzi, Michael E FieldAbstract:Abstract A multi-year study was conducted on a shallow Fringing Reef flat on Molokai, Hawaii to determine the temporal and spatial dispersal patterns of terrigenous suspended sediment. During this study, trade-wind conditions existed for the majority of the year on the Reef flat. The trade-wind conditions produced strong currents and resuspended moderate amounts of sediment on the Reef flat on a daily basis during the year of study, resulting in an overwhelming contribution to the total sediment flux. The magnitude and direction of the trade winds relative to the orientation of the coastline, the shallow-relief and broad morphology, and tidal elevation, provided the primary control of the physical processes that resuspended and transported sediment on the Reef flat over the period of record. Spatial data indicate that much of the terrigenous sediment resuspended on the Reef flat is transported predominantly alongshore and is confined to the inner- to mid-Reef flat. Evidence for the limited across-shore mixing and transport is provided by the dominantly alongshore wind-driven currents during trade-wind conditions and the well-defined across-shore gradient in percentage calcium carbonate of the suspended sediment. Regions of slightly offshore suspended-sediment transport along the Reef flat can be attributed to the circulation pattern set up by the interaction between the trade winds, coastal morphology, and anthropogenic coastal structures (i.e., fish ponds and wharf). The regions in which sediment were seen to move offshore provide the strongest link between the sediment dynamics on Reef flat and fore Reef, and qualitatively appears to be correlated with low coral coverage on the fore Reef.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance.
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sediment resuspension and transport patterns on a Fringing Reef flat molokai hawaii
Coral Reefs, 2004Co-Authors: Andrea S Ogston, Curt D Storlazzi, Michael E Field, M K PrestoAbstract:Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of Reef environments well established. This study of sediment resuspension, transport, and resulting deposition on a Fringing Reef flat off Molokai, Hawaii, uses a year of time-series data from a small, instrumented tripod. It shows the importance of trade winds and ocean wave heights in controlling the movement of sediment. Sediment is typically resuspended daily and the dominant controls on the magnitude of events (10–25 mg/l) are the trade-wind-generated waves and currents and tidal elevation on the Reef flat. The net flux of sediment on this Reef is primarily along the Reef flat in the direction of the prevailing trade winds (to the west), with a secondary direction of slightly offshore, towards a zone of low coral abundance. These results have application to Reef studies and Reef management in other areas in several ways. First, the observed resuspension and turbidity results from fine-grained terrigenous sediment that appears to be trapped and recycled on the Reef flat. Thus corals are subjected to light attenuation by the same particles repeatedly, however small the amount. Secondly, the measurements show high temporal variability (from daily to seasonal scales) of sediment resuspension, indicating that single measurements are inadequate to accurately describe conditions on a Reef flat.
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quantitative morphology of a Fringing Reef tract from high resolution laser bathymetry southern molokai hawaii
Geological Society of America Bulletin, 2003Co-Authors: Curt D Storlazzi, Joshua B Logan, Michael E FieldAbstract:High-resolution Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) laser-determined bathymetric data were used to define the morphology of spur-and-groove structures on the Fringing Reef off the south coast of Molokai, Hawaii. These data provide a basis for mapping and analyzing morphology of the Reef with a level of precision and spatial coverage never before attained. An extensive Fringing coral Reef stretches along the central two-thirds of Molokai9s south shore (∼40 km); along the east and west ends there is only a thin veneer of living coral with no developed Reef complex. In total, ∼4800 measurements of spur-and-groove height and the distance between adjacent spur crests (wavelength) were obtained along four isobaths. Between the 5m and 15m isobaths, the mean spur height increased from 0.7 m to 1.6 m, whereas the mean wavelength increased from 71 m to 104 m. Reef flat width was found to exponentially decrease with increasing wave energy. Overall, mean spur-and-groove height and wavelength were shown to be inversely proportional to wave energy. In high-energy environments, spur-and-groove morphology remains relatively constant across all water depths. In low-energy environments, however, spur-and-groove structures display much greater variation; they are relatively small and narrow in shallow depths and develop into much larger and broader features in deeper water. Therefore, it appears that waves exert a primary control on both the small- and large-scale morphology of the Reef off south Molokai.
Meixia Zhao - One of the best experts on this subject based on the ideXlab platform.
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seasonal variations of seawater pco2 and sea air co2 fluxes in a Fringing coral Reef northern south china sea
Journal of Geophysical Research, 2016Co-Authors: Hongqiang Yan, Meixia Zhao, Qi Shi, Tianran Chen, Guohui Liu, Yehui Tan, Yinghui WangAbstract:Evidence based on four field surveys conducted between July 2009 and April 2011 indicates that both sea surface partial pressures of CO2 (pCO(2)) and sea-air CO2 fluxes at Luhuitou Fringing Reef in Sanya, Hainan Island, northern South China Sea (SCS) are subject to significant seasonal variations. The diurnal variation of seawater pCO(2) ranges from 264 to 579 mu atm in summer, which is much larger than that in autumn (152-335 mu atm), in winter (84-260 mu atm), and in spring (114-228 mu atm). The sea-air CO2 flux in summer (similar to 9.6 mmol CO2 m(-2) d(-1)) is also larger than that in other seasons (i.e.,similar to 3 mmol CO2 m(-2) d(-1) in spring, similar to 3.5 mmol CO2 m(-2) d(-1) in autumn, and similar to 2.7 mmol CO2 m(-2) d(-1) in winter). The atmospheric pCO(2) in this Reef shows small diurnal and seasonal variations. The integration of the time-series pCO(2) data shows that the Reef area is a weak source of atmospheric CO2 at similar to 0.54 mol CO2 m(-2) yr(-1). Further analyses indicate that the seasonal variations of the surface seawater pCO(2) in Luhuitou Fringing Reef are mainly affected by seasonally-dependent biological metabolic processes (organic processe and inorganic process), and that the organic process play a more important role than the inorganic process. Seasonal sea surface temperature (SST) variations and hydrodynamic processes may also have some influence on seawater pCO(2) variation.
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age structure of massive porites lutea corals at luhuitou Fringing Reef northern south china sea indicates recovery following severe anthropogenic disturbance
Coral Reefs, 2014Co-Authors: Meixia Zhao, Q M Zhang, Qi Shi, George RoffAbstract:Luhuitou Fringing Reef at Hainan Island (northern South China Sea) has experienced severe anthropogenic disturbance, with live coral cover declining by > 80 % since the 1960 s. To assess the size structure of Porites lutea, we measured the sizes of 1,857 colonies from the Reef flat (0 m) and slope (2–4 m depth). Both populations were positively skewed and leptokurtic in shape, indicating a high abundance of smaller colonies (averaging 21.4 ± 2.3 cm on the flat and 31.9 ± 2.8 cm on the slope). Age structure of populations was determined through growth rates extracted from X-rays of P. lutea cores. The majority of colonies (> 95 %) were < 50 yr old, with 55 % of P. lutea on the Reef flat having recruited following the establishment of a marine reserve in 1990. The abundance of younger colonies indicates significant recovery of P. lutea following the removal of chronic anthropogenic disturbance.
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estimate of carbonate production by scleractinian corals at luhuitou Fringing Reef sanya china
Chinese Science Bulletin, 2009Co-Authors: Qi Shi, Meixia Zhao, Qiaomin Zhang, Tianran Chen, Hankui WangAbstract:Carbonate production by scleractinian corals not only maintains coral Reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scleractinian corals at Luhuitou Fringing Reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 +/- 0.55 kg center dot m(-2) center dot a(-1) and 3.52 +/- 1.32 kg center dot m(-2) center dot a(-1) on the Reef flat and Reef slope, respectively, depending on the composition and distribution of corals and the intergeneric difference of skeletal growth. In response to the rapidly increasing human impacts, coral carbonate production has decreased by 80%-89% at this Fringing Reef since the 1960s; as a result, the Reef accretion rate declined and became lower than the rate of sea level rise. Further development of the Luhuitou Fringing Reef will switch significantly from lateral extension seawards to vertical growth, reflecting a response of coral Reef bio-geomorphic process to strong human impacts under the background of global sea level rise. In addition, decrease in coral carbonate production reduced CO2 release from this Fringing Reef. In the future, it is likely that the role played by coral Reefs, especially of Fringing Reefs, in the ocean and even in the global carbon cycle will be modified or weakened by the increasing human impacts.
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status monitoring and health assessment of luhuitou Fringing Reef of sanya hainan china
Chinese Science Bulletin, 2006Co-Authors: Qiaomin Zhang, Qi Shi, Hankui Wang, Gang Chen, T C W Fong, D C C Wong, Hui Huang, Meixia ZhaoAbstract:The monitoring survey and health assessment for benthic community were carried out in Luhuitou Fringing Reef of Sanya, Hainan, China in 2002. Monitoring survey included manta tow, line intercept transect, video transect and digital photograph. The mean live coral cover was 23.40%. Comparison of used monitoring methods showed that video transect can replace line intercept transect, and 50 m transect is better than 20 m transect in uneven coral region. Survey data and comparison with previous research work showed that Luhuitou Fringing Reef has been damaged severely and has a general declining trend with live coral cover from about 85% in the 1960s down to 20% in 2004, but it still has quite high biodiversity and therefore has special protection value. Main factors of Luhuitou Fringing Reef declining were human activities including Reef rock digging and curios collecting, destructive fishing, sediment and pollutant from coastal land, and recent marine aquaculture. Only strengthening integrated management can reach improvement and restoration of Luhuitou declining coral Reef ecosystem.
