The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area.Results showed that the highest concentrations of picoplankton and ...The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area.Results showed that the highest concentrations of picoplankton and phytoplankton were found in the middle and inner part of the lagoon,irrespective of the tides.The MDS result also revealed that phytoplankton communities,dominated by Ceratium furca,were similar among stations in the inner bay during both flood tides and ebb tides.The time series sampling results at the inlet-outlet channel revealed that almost the same amounts of phytoplankton and picoplankton were carried through the channel during flood and ebb tides,with no trend in nutrient fluctuations except for phosphate which had a net loss from the lagoon.The results showed that tidal cycles do not effectively flush away phytoplankton and picoplankton from the lagoon,and the blooming of phytoand picoplankton is inevitable should the situation stay the same.Steps are needed to alleviate the eutrophication condition instead of depending on the natural process such as tidal cycle.展开更多
The data from Acoustic Doppler Current Profiler （ADCP） of the three-dimensional current-field, echo intensity, modulation of Suspended Sediment Concentration （SSC）, and related water levels and wind velocities hav...The data from Acoustic Doppler Current Profiler （ADCP） of the three-dimensional current-field, echo intensity, modulation of Suspended Sediment Concentration （SSC）, and related water levels and wind velocities have been analyzed as a function of water depth above submerged asymmetric compound sand waves during a tidal cycle in the Lister Tiefofthe German Bight in the North Sea. Signatures of vertical current component, echo intensities and calculated SSC modulations in the water column depend strongly on wind and current velocity. Bursts of vertical current component and echo intensity are triggered by sand waves itself as well as by superimposed megaripples due to current wave interaction at high current ≥ 1.0 m＇s1 and wind speeds ≥ 10.0 m·s^-1, preferably of opposite directions, measured at high spatial resolution. The magnitude of currents and SSC modulations during ebb and flood tidal current phases are only weakly time dependent, whereas the local magnitudes of these parameters are variable in space above the sand waves. Some hydrodynamic parameters are further investigated and analyzed, showing a consistence of ADCP measurements in the applied theory.展开更多
基金supported by the Dapeng Bay National Scenic Area Ad-ministration to PJ Meng and by the National Science Council,Taiwan,China to KS Tew (NSC94-2621-B-291-002)
文摘The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area.Results showed that the highest concentrations of picoplankton and phytoplankton were found in the middle and inner part of the lagoon,irrespective of the tides.The MDS result also revealed that phytoplankton communities,dominated by Ceratium furca,were similar among stations in the inner bay during both flood tides and ebb tides.The time series sampling results at the inlet-outlet channel revealed that almost the same amounts of phytoplankton and picoplankton were carried through the channel during flood and ebb tides,with no trend in nutrient fluctuations except for phosphate which had a net loss from the lagoon.The results showed that tidal cycles do not effectively flush away phytoplankton and picoplankton from the lagoon,and the blooming of phytoand picoplankton is inevitable should the situation stay the same.Steps are needed to alleviate the eutrophication condition instead of depending on the natural process such as tidal cycle.
文摘The data from Acoustic Doppler Current Profiler （ADCP） of the three-dimensional current-field, echo intensity, modulation of Suspended Sediment Concentration （SSC）, and related water levels and wind velocities have been analyzed as a function of water depth above submerged asymmetric compound sand waves during a tidal cycle in the Lister Tiefofthe German Bight in the North Sea. Signatures of vertical current component, echo intensities and calculated SSC modulations in the water column depend strongly on wind and current velocity. Bursts of vertical current component and echo intensity are triggered by sand waves itself as well as by superimposed megaripples due to current wave interaction at high current ≥ 1.0 m＇s1 and wind speeds ≥ 10.0 m·s^-1, preferably of opposite directions, measured at high spatial resolution. The magnitude of currents and SSC modulations during ebb and flood tidal current phases are only weakly time dependent, whereas the local magnitudes of these parameters are variable in space above the sand waves. Some hydrodynamic parameters are further investigated and analyzed, showing a consistence of ADCP measurements in the applied theory.
