Ikuo Souta*, Nobuo Awaji* and Seiiti Kaneko**

*Kanagawa Prefectural Environment Research Center
**Kanagawa Prefectural Public Health Laboratory

+ Correspondence should be addressed to Ikuo Souta:
Kanagawa Prefectural Environment Research Center
(842, Nakahara-shimojuku, Hiratsuka, Kanagawa 254 Japan)

Abstract

Typical seaweeds, found washed up on the beach, were collected and placed into columns (80cm in height and 25cm in diameter) made of vinyl chloride or glass for the purpose of studying aerobic and anaerobic decomposition of seaweed. During the experimental period, the columns were washed once weekly with 1.5 liters of distilled water and seawater. The effluent was analyzed to characterize seaweed decomposition. In addition, seaweed samples were incubated by the batch method, adding various nutrient salts to the medium. The following results were obtained: 1. Microorganisms such as viblio sp. and pseudomonas sp. were found to be involved in the decomposition of seaweeds. The activity of these microorganisms is thought to be associated with salt concentrations. 2. At the beginning of the experiment, the levels of TC and BOD in the effluent were high, due to the decomposing activity of microorganisms. 3. The level of alginic acid was lower after aerobic decomposition than after anaerobic decomposition. Conversely, the TC level and the decomposition rate were higher with aerobic decomposition. 4. In the experiment involving the addition of various nutrient salts, the decomposition velocity of the seaweeds was about 3 times higher in the presence of ammonium dihydrogenphosphate than in its absence.

Key words: microbial decomposition, seaweed, oceanic bacteria, pseudomonas sp., nutrient salt