The present study was carried out to examine changes in distribution of Ampelisca, an infaunal tube dweller at Igarashi Beach in Niigata prefecture on the Japan Sea during April 1992 to December 1993. The dominant Ampelisca at Igarashi Beach were A. naikaiensis and A. brevicornis. A. naikaiensis was found to be distributed in waters below 8m in depth, while A. brevicornis was found in waters between 6-30m in depth during summer to early autumn, and was found below depth 10m in early spring and early winter. There was no remarkable relationship between distribution range in Ampelisca and environmental factors i.e. seasonal changes in water temperature, salinity, and particle size and ignition loss of bottom material. Changes in distribution are well explained through relations to the seasonal frequency of days with strong winds (>8m/s, WSW-NE) which cause waves over 1m height, known to change the bottom topography in waters shallower than 12m depth in the open coast near Igarashi Beach. In this study, Ampelisca was found only at the stations where changes in bottom topography by high waves is expected to be minimal. These facts suggest that changes in bottom topography by high waves might prevent Ampelisca from building living tubes in open coast like Igarashi Beach.

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TOPEX and POSEIDON altimeters are on board the same satellite and measure the sea surface topography, alternatively. Here the relative bias between the two altimeters is estimated. Data for five orbits over the North Pacific are analyzed. The relative bias is found to be about 22cm and considerably stable, not depending on the orbit and the observation time. The value is consistent with that indicated by the calibration by in situ data. The effectiveness of adding the constant relative bias to the POSEIDON altimeter data is demonstrated by the comparison with in situ sea level data. Corrected POSEIDON altimeter data are also obtained by linearly interpolating the TOPEX altimeter data closed in time instead of adding the constant value. In comparison of both results with in situ sea level data, the correlation is higher for the latter corrected data.

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TOHOKU-II Wave Model which is based on the similarity law for a growing wind wave field, is suitable for a wave prediction method in inland sea where wind waves are dominant. We now devised this wave prediction model for a shallow water by introducing a energy dissipation effect of a friction at sea bottom. The growth characteristics for wave height and period calculated by the devised TOHOKU shallow water wave model show a few percent heigher than Bretschneider's empirical formula in the case of a simple condition as a uniform depth. A comparison of the estimated value with the observation data at Tokyo lighthouse shows so small RMS error that this model is sure to be effective for a practical application.

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Hydrothermal vents serve as the "oases" for the animals inhabiting the deep-sea "deserts". The biomass of the vent communities is outstanding in the sterile deep-sea habitats; it is remarkable even in the whole marine environment. The vent communities are primarily supported by microbial chemosynthetic production, largely based on sulfur oxidation. The fraction of sulfur-oxidizing bacteria in the microflora in the hydrothermally affected waters (plumes) was notably higher than that in non-plume waters. Planktonic bacteria in the plumes were shown to have high production rates and thus contribute to vent animals as particulate food sources. This contribution may be magnified by the capability of aggregate formation. Size is a food quality determining the food value, and the value of bacterial aggregates over bacterial cells is obviously high, considering rice grains and rice balls. Aggregate formation was often observed with the planktonic bacteria in and from the hydrothermal plumes. Thus, planktonic bacteria were thought to contribute to the vent communities at least in a dual manner: by high production and aggregate formation.

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