The main sources of nitrogen and phosphorus in Hakata Bay are the effluent from the sewage disposal plants and the bay sediments. The present paper deals with the utilization of nitrogen and phosphorus which are contained in the effluent from Fukuoka Eastern Sewage Disposal Plant and released from the sediment in Hakata Bay by an important laver in fishery, Porphyra yezoensis and its competitors such as green lavers Enteromorpha sp. and Ulva pertusa and also a diatom Skeletonema costatum. 1. All lavers used in the experiment utilized NH4-N from the effluent and bay sediment rather than NO3-N in the standard medium. The weight increment of Enteromorpha sp. was the highest among the tested lavers corresponding to about twice that of P. yezoensis, but no difference was observed in absorption of N and P between both lavers. Those of U. pertusa were the lowest among the lavers used. 2. Although the growth of S. costatum decreases with lowering temperature, its weight gain and the absorbed amounts of N and P were much larger as compared with those of P. yezoensis even at 10°C, corresponding to 15, 6 and 12 times, respectively. 3. The growth of P. yezoensis was not affected by S. costatum coexisting in the same media, when the amounts of nutrients in the media were sufficient. 4. The growth of P. yezoensis and S. costatum was inhibited with the increase of NH4-N level in media more than 8 mg/l and 12 mg/l, respectively. However, S. costatum was more affected by the high level of NH4-N than P. yezoensis, resulting in the rapid decrease of cell number and the death of almost all cells at 32 mg/l after 4 days culture, whereas in the same medium P. yezoensis showed the growth ca. half that in the standard medium (NO3-N) after 3 days. 5. The toxicity of NH4-N to P. yezoensis in the effluent media was lower than that in the artificial media which contain NH4Cl as N-source, resulting in the almost same growth even at 14 mg/l of NH4-N with that in the standard media containing NaNO3 as N-source.
|Number of pages
|Published - 1987
All Science Journal Classification (ASJC) codes
- General Medicine