The asphaltene fraction of Murban crude oil, refractory compositions, eluted by activated alumina column chromatography with methanol, was degraded by marine bacteria from the sediments of Tokyo Bay. In the sediment of Arakawa Offing, 40% of asphaltene fraction of Murban crude oil was degraded in 20 days under aerobic condition and 17% was degraded in 30 days under anaerobic condition at 20°C. Under aerobic condition, the maximum degradation rate of asphaltene fraction was 0.07-0.08 mg day^-1 g^-1 dry sediment at the Arakawa Offing, 0.11mg day^-1 g^-1 dry sediment at the Point A and 0.10mg day^-1 g^-1 dry sediment at the Ooi Wharf. Under anaerobic condition, the rate was 0.02-0.03mg day^-1 g^-1 dry sediment at the Arakawa Offing. In the sediments of the Tokyo Bay, the number of asphaltene fraction degrading bacteria was 6.8×10³-1.46×10⁵ cells g^-1 dry sediment, and it was 1.0-3.0% of aerobic heterotrophic bacteria.

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Methods for estimating sea surface velocity from NOAA/AVHRR images have recently been developed. A feature tracking method is a subjective method, while a maximum cross-correlation method and an inverse method are objective methods. These methods are reviewed and compared with each other in the present paper. Moreover, a method for estimating surface geostrophic current from one NOAA/AVHRR image is discussed.

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Major research activities during the last 30 years of the author awarded the society prize for 1992 have been summarized. Research was started for the evaluation of environmental parameters on in situ changes of photosynthetic bacterial population using a newly developed mathematical growth model in 1963, and the model was later applied for algal populations. The developed research direction was fully described in a book, 'Biological Oceanographic Processes', published in 1973. Involvement with a bottom-up control of ecosystem by fertilization carried out in Canada in order to enhance sockeye salmon production was mentioned. Experiments by manipulating ecosystems conducted using mesocosms in the international program called CEPEX starting in 1973 were then described. Since 1977, research activities were focussed on the control of phytoplankton community structure of red tides, and upwelled and open-ocean water masses in relation to the surrounding environment as determinant. Research direction has recently been focussed further on the analysis how to develop such a great diversified phytoplankton species under rather limited but greatly fluctuated ranges of ocean environment by knowing response characteristics of each species to environmental parameters.

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