The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is hi...The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is highly complicated. The cord-grass Spartina alterniflora, which was introduced artificially into the Jiangsu coast, has significant influences on the regional tidal flat evolution in terms of deposition rate, spacial sediment distribution patterns and tidal creek morphology. On the basis of the data set of bed elevation and accumulation rate for different periods of time, the applicability of the Pethick - Allen model to the Jiangsu tidal salt marshes is discussed. In addition, caesium-137 dating was carried out for sediment samples collected from the salt marsh of the Wangang area. In combination with the caesium-137 analysis and the data collected from literature, the Pethick - Allen model was used to derive the accumulation rate in the Wanggang tidal flat for the various periods. The results show that the pattern of tidal flat accretion has been modified, due to more rapid accretion following the iatroduction of S. alterniflora to the region. Surficial sediment samples were collected from representative profiles and analyzed for grain size with a laser particle analyzer. The result shows that fine-grained sediment has been trapped by the plant, with most of the sediment deposited on the Suaeda salsa and Spartina angelica flats being derived from drainage creeks rather than the from gently sloping tidal flats. Remote sensing analysis and in situ observations indicate that the creeks formed in the S. alterniflora flat have a relatively small ratio of width to depth, a relatively high density, and are more stable than the other tidal flat creek systems in the study area.展开更多
Located in Chiba Prefecture, the Yatsu Tidal Flat is an important stopover for birds migrating between cold regions such as Siberia and warm regions such as Southeast Asia and Australia. Its importance led to its sele...Located in Chiba Prefecture, the Yatsu Tidal Flat is an important stopover for birds migrating between cold regions such as Siberia and warm regions such as Southeast Asia and Australia. Its importance led to its selection in 1993 as the first tidal flat in Japan to be registered under the Convention on Wetlands of International Importance especially as Waterfowl Habitat (the Ramsar Convention). However, the Yatsu Tidal Flat has in more recent years witnessed blooms of Ulva spp. (sea lettuce) and an increase in exotic species such as Batillaria attramentaria (Japanese mud snail) and Mercenaria mercenaria (hard clam), fueling concerns that the increasing spatial domination of the tidal flat by such species and competition with other species for food may drive a decline in the habitat’s self-cleaning capabilities. For this study, we focused on Batillaria attramentaria, which is now so widely distributed in the Yatsu Tidal Flat as to preclude reliable monitoring via aerial photographs or satellite imagery. Accordingly, we tested the utility of a simplified method for obtaining data on the distribution of Batillaria attramentaria by using aerial balloon photography and a vegetation index camera capable of generating NDVI data. Our results show that under certain conditions, this method can indeed be used to determine Batillaria attramentaria distribution.展开更多
During the past century,natural and human modifications of environmental systems have greatly accelerated coastal salt marsh deterioration and shoreline retreat in many regions worldwide. Field investigation,profile a...During the past century,natural and human modifications of environmental systems have greatly accelerated coastal salt marsh deterioration and shoreline retreat in many regions worldwide. Field investigation,profile analysis,geographical information analysis,and remote sensing were employed in combination to study the effect of sediment on Spartina alterniflora salt marshes of the coast in Jiangsu Province,East China. The results indicated that the propagation of Spartina alterniflora salt marshes was closely related to regional sediment conditions,especially the supply of fine-grained materials. Additionally,because of the dense and high grass in Spartina alterniflora salt marshes,wave energy and tidal currents were baffled and weaker than those of the adjacent,unvegetated mud flats. Fine sediment was hardly resuspended under the low energy conditions in the Spartina alterniflora salt marshes.展开更多
基金supported financially by the National Natural Science Foundation of China under contract Nos 40231010 and 40476041the Marine Science Youth Fund of State 0ceanic Administration of China under contract No.2006312.
文摘The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is highly complicated. The cord-grass Spartina alterniflora, which was introduced artificially into the Jiangsu coast, has significant influences on the regional tidal flat evolution in terms of deposition rate, spacial sediment distribution patterns and tidal creek morphology. On the basis of the data set of bed elevation and accumulation rate for different periods of time, the applicability of the Pethick - Allen model to the Jiangsu tidal salt marshes is discussed. In addition, caesium-137 dating was carried out for sediment samples collected from the salt marsh of the Wangang area. In combination with the caesium-137 analysis and the data collected from literature, the Pethick - Allen model was used to derive the accumulation rate in the Wanggang tidal flat for the various periods. The results show that the pattern of tidal flat accretion has been modified, due to more rapid accretion following the iatroduction of S. alterniflora to the region. Surficial sediment samples were collected from representative profiles and analyzed for grain size with a laser particle analyzer. The result shows that fine-grained sediment has been trapped by the plant, with most of the sediment deposited on the Suaeda salsa and Spartina angelica flats being derived from drainage creeks rather than the from gently sloping tidal flats. Remote sensing analysis and in situ observations indicate that the creeks formed in the S. alterniflora flat have a relatively small ratio of width to depth, a relatively high density, and are more stable than the other tidal flat creek systems in the study area.
文摘Located in Chiba Prefecture, the Yatsu Tidal Flat is an important stopover for birds migrating between cold regions such as Siberia and warm regions such as Southeast Asia and Australia. Its importance led to its selection in 1993 as the first tidal flat in Japan to be registered under the Convention on Wetlands of International Importance especially as Waterfowl Habitat (the Ramsar Convention). However, the Yatsu Tidal Flat has in more recent years witnessed blooms of Ulva spp. (sea lettuce) and an increase in exotic species such as Batillaria attramentaria (Japanese mud snail) and Mercenaria mercenaria (hard clam), fueling concerns that the increasing spatial domination of the tidal flat by such species and competition with other species for food may drive a decline in the habitat’s self-cleaning capabilities. For this study, we focused on Batillaria attramentaria, which is now so widely distributed in the Yatsu Tidal Flat as to preclude reliable monitoring via aerial photographs or satellite imagery. Accordingly, we tested the utility of a simplified method for obtaining data on the distribution of Batillaria attramentaria by using aerial balloon photography and a vegetation index camera capable of generating NDVI data. Our results show that under certain conditions, this method can indeed be used to determine Batillaria attramentaria distribution.
基金the National Natural Science Foundation of China (Nos.40401059 and 40576040).
文摘During the past century,natural and human modifications of environmental systems have greatly accelerated coastal salt marsh deterioration and shoreline retreat in many regions worldwide. Field investigation,profile analysis,geographical information analysis,and remote sensing were employed in combination to study the effect of sediment on Spartina alterniflora salt marshes of the coast in Jiangsu Province,East China. The results indicated that the propagation of Spartina alterniflora salt marshes was closely related to regional sediment conditions,especially the supply of fine-grained materials. Additionally,because of the dense and high grass in Spartina alterniflora salt marshes,wave energy and tidal currents were baffled and weaker than those of the adjacent,unvegetated mud flats. Fine sediment was hardly resuspended under the low energy conditions in the Spartina alterniflora salt marshes.
