The study on the mechanisms of ecosystem in the trophic level and charcterization of organic matters in the Suruga Bay on the utilization of deep seawater

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1) Deep seawater in the Suruga Bay is pumped up from 397m-depth and 687m-depth with 24m-depth of surface layer water. The main purpose of this study is to understand the controlling factors of ecosystem dynamics at Suruga Bay from surface to deep layers and also to characterize organic matters produced by biological processes. Seasonal studies at the field and mesocosms experiments have been carried out during three years. A well-developed ecosystem in both 400m depths and 700m-depth seawater was developed, with including members of grazing food web and a sufficient microbial loop for the re-mineralization of organic mattes. The amount of fixed organic matter during 11 days of incubation was near 60 times and 100 times for 400m depths and 700m depths respectively. The response of deep-sea water from both depths is different in terms of time scale (rapid in case of 700m than that of 400m) and species composition.2) The measurement of radiocarbon showed that age of deep seawater in the Suruga bay ranges from 400 years for 400m and 1000 years for 1000m-depth. Organic matters were characterized as amino acids, phospholipids, carbohydrate, and most of organic matters of molecular weight is below 1000 daltons (90%).