2024-03-29T13:32:42Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/566672022-11-17T02:08:08Zhdl_2115_20049hdl_2115_141High tolerance of phytoplankton for extremely high ammonium concentrations in the eutrophic coastal water of Dokai Bay (Japan)Suksomjit, MarutTada, KuninaoIchimi, KazuhikoMontani, ShigeruAmmonium toxicitygrowth inhibitionDokai Bay660The tolerance of phytoplankton in Dokai Bay for an extremely high ammonium concentration in culture media has been studied. Six species of phytoplankton, three diatoms (two clones of Skeletonema sp. and Chaetoceros sp.) and three flagellates (Heterosigma akashiwo, Chattonella antiqua and Karenia mikimotoi) were grown in various concentrations of NH4Cl. The results suggested that high ammonium concentrations had negative effects on phytoplankton growth. Non-indigenous species in Dokai Bay, Japan, C. antiqua and K. mikimotoi, were unable to grow at 200 and 150 μ M, respectively. Growth rates of Skeletonema sp. isolated from Harima Nada (Seto Inland Sea, Japan), Chaetoceros sp. and H. akashiwo were reduced significantly at higher ammonium concentrations compared to the control treatment. However, such a high ammonium concentration of even 1,500 μ M could not produce a significant adverse effect on the growth rate of Skeletonema sp. isolated from Dokai Bay. Furthermore, the maximum chlorophyll fluorescence of tested species was also gradually decreased with an increase in ammonium concentration. The influence of a high ammonium level on phytoplankton growth observed in this study confirmed the phytoplankton species composition observed in Dokai Bay. Our results suggested that such a high ammonium concentration was an important factor in determining the species composition of the phytoplankton assemblage in that bay.日仏海洋学会Journal Articleapplication/pdfhttp://hdl.handle.net/2115/56667https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/56667/1/la%20mer%2047%20montani%28OCR%29.pdf0503-1540AN00019968うみ47375882009-11-28engpublisher