The effects of the reed, Phragmites australis (Trin.), growing in a brackish water lagoon, were studied in relation to the grain-size distribution of the substratum. At the salt marshes near the lagoon, the upper soils from the surface to a depth of 20cm contained much silt-clay. These fine particles were found to be transferred from the river and fish ponds near the lagoon, and to be deposited when the tidal rhythm changed, that is, when the water current stopped. In addition, the fine particles, which were deposited on the bottom of the lagoon adjacent to the marshes, became resuspended as a result of wind-caused wave action, and then were transported and redeposited in the salt marshes at the flood tide. Since the reeds further reduced the water current caused by the waves and tide, the reeds were thought to promote redeposition of the resuspended matter. In other words, the reeds were considered to protect deposited and redeposited particles such as silt and clay from resuspension as a result of wave action by reducing the effects of waves and wind. These, processes suggested that silt-clay will become abundant in the substratum of the salt marsh adjacent to the lagoon.

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Severe red tides due to Chattonella antiqua occur sporadically during summer in the Seto Inland Sea, Japan, and cause significant damage to the fishing industry. In order to assess the chemical environment with respect to the outbreak of C. antiqua, environmental factors that affect the growth of C. antiqua were monitored around the le-shima Islands, the Seto Inland Sea, in the summer of 1986. In addition, a growth bioassay of the seawater using C. antiqua was conducted under a semicontinuous culture system. Although temperature, salinity and light intensity were optimum for the growth of C. antiqua, red tides by this species did not occur. Concentrations of NH₄⁺, NO₃^- and PO₄^3- were low (<0.4, <0.2, <0.06μM, respectively) above the thermocline (8-12m) and high below it (0.6-2, 4-8, 0.4-0.8μM, respectively). Vitamin B₁₂ concentrations did not change significantly between the surface (0m) and below the thermocline (25m) in the level of 2-4ng·l^-1. The growth bioassay revealed that in the surface waters, concentrations of N- as well as 13- nutrients were too low to support a rapid growth of C. antiqua. At the depth of 25m, neither N, P nor B₁₂ limited the growth rate.
In order to obtain more quantitative information on the growth rate as a function of the concentrations of N-and P- nutrients, C. antiqua was grown in a semicontinuous culture system by changing nutrient concentrations systematically. The observed growth rate (μ) can be approximated as follows:μ=μ_max·S_N/K_g^N·S_PO4/K_g^P+S_PO4, where SN is the concentration of NO₃^- plus NH₄⁺ (0-6μM), S_PO4 the concentration of PO₄^3- (0-0.6μM), μ_max (0. 97 d^-1) the maximal growth rate, K_g^N (1.0μM) and K_g^P (0.11μM) the half saturation constants for NO₃^- and PO₄^3-, respectively. Using the above equation with nutrient concentrations measured, the rate at which seawater supports the growth of C. antiqua can be estimated and this can be used for the assessment of chemical environments with respect to the outbreak of C. antiqua.

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To investigate the fluctuation of the Kuroshio front, moored current meters were deployed near the shelf break and on the continental slope in the East China Sea, northwest of Okinawa Island, during a period from 25 June to 22 July 1984. Two mooring arrays were deployed on the slope of about 800m water depth (under the Kuroshio), about 30km apart along the path of the Kuroshio. Another two arrays were set near the shelf break of about 300m water depth.
The fluctuation of current on the slope is found to have a predominant period of 11-14 days and a wave length of 300-350km, propagating toward the downstream direction of the Kuroshio with a phase velocity of about 30 cm sec^-1. When the Kuroshio front approaches the shelf break and the crest of the meander covers the mooring site, the current direction moves toward the downstream direction of the Kuroshio and the water temperature increases. On the other hand, when the trough of the meander covers the mooring site, the current direction changes offshoreward across the Kuroshio or in the upstream direction of the Kuroshio, and the water temperature decreases. Three-dimensional distributions of water temperature and salinity around the mooring site were observed with a CTD twice at 5.5 days intervals, which indicate the meanders of the front is about 180°C out of phase. This coincides with a period of 11-14 days obtained with the moored current meters. Wave lengths of the dominant meander of the front in the satellite thermal images were about 350km and 100-200km, which also coincides with results obtained with the moored current meters.

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Various wind velocities u, Uλ/2, Uλ and U₁₀ are correlated to the measured growth rate of water waves β, where u is the friction velocity of the wind, and Uλ/2, Uλ and U₁₀ are the wind speeds respectively at the heights λ/2, A and 10m above sea surface (λ: wave length). It is shown that within a range of the dimensionless wind speed, 0.1<u/C<0.6, there are no appreciable differences in the correlations, where C is the phase velocity of water waves. The present relation between β and Uλ shows qualitatively similar properties as the one obtained by Al'Zanaidi and Hui (1984): the growth rate for waves with rough surface is larger than that with smooth surface. However, our present relations give, for the both waves with different surface roughness, larger values by factors 1.7-1.8 than those given by Al'Zanaidi and Hui's relation.

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The structure of the turbulent boundary layer underneath laboratory wind waves was studied by using a combination of a high-sensitivity thermometer array with a two-component sonic flowmeter. The temperature fluctuations are used to detect movements of water parcels, with temperature as a passive quantity. The turbulence energy was dominant in the frequency range (0.01-0.1Hz), which was much smaller than the wind-wave frequency (2-5Hz), and in which the turbulence was anisotropic. There was a frequency range (0.2-2Hz for velocity, 0.2-5Hz for temperature fluctuation) where the turbulence was isotropic and had a-5/3 slope in the energy spectrum. These points are the same as those in previous works. However, by analyses of the time series by using a variable-interval time-averaging technique (VITA), it has been found that conspicuous events in this main turbulence energy band are the downward bursting from the vicinity of the water surface. Thus the structure of the water layer underneath the wind waves has characters which are similar to the familiar turbulent boundary layer over a rough solid wall, as already conceived. It has been found that, at the same time, the turbulence energy can be related to quantities of the wind waves (the root mean squared water level fluctuation and the wave peak frequency), for different wind and wave conditions. That is, the turbulence underneath the wind waves develops under a close coupling with the wind waves.

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