Disappearance of Hypoxia in Dokai Bay

Part of the Estuaries of the World book series (EOTW)


Dokai Bay, in northern Kyushu, Japan, though small in size is an important port for the huge heavy and chemical industrial facilities that surround the bay. In the past, it was also a discharge area for heavily polluted industrial waters. Long-lasting hypoxia events were observed over large parts of the bay in the 1990s, but loads of total phosphorus (TP) and total nitrogen (TN) in wastewater have been controlled since 1980 and 1996, respectively, by government regulations. In consequence, TP and TN concentrations derived from nutrients such as phosphate-phosphorus and ammonium-nitrogen have substantially decreased. In addition, the concentration of acid-volatile sulfides in sediments has decreased drastically.

Because of decreased eutrophication, the severity and duration of the hypoxia events have decreased, and, although the red tide formation frequency has not changed, the diversity of red tide organisms has increased. Macroalgae have expanded their distribution to inner and deeper parts of the bay as the light penetration has increased. Sessile animals as well as fish, shrimp, and crabs are significantly more abundant on the bottom of the inner bay because of the increased dissolved oxygen content, especially in summer.

A bioremediation study of the filter-feeding mussel Mytilus galloprovincialis at a demonstration facility in the bay revealed that water purification by this mussel reduced the density of red tide organisms. In addition, the facility serves as a gathering place for fishes and as an environmental education site. Moreover, mussels collected from the facility are mixed with wood chips and composted for fertilizer. A seaweed bed bioremediation facility also enriches the ecosystems in the bay. With the disappearance of hypoxic areas, water quality has greatly improved, and it is hoped that restoration of their habitats will cause species that previously lived in the bay to return in abundance. The optimum eutrophic level for the bay still needs to be determined cooperatively by government agencies, stakeholders, and specialists, taking into account the richness of its aquatic resources.


Eutrophication Dokai Bay Hypoxia Restoration Ecological improvement 



I am grateful to Dr. Naoko Ueda, Dr. Ken-ichiro Hamada, and Mr. Tatsumi Murata of the University of Kitakyushu for providing recent useful biological and chemical data. I also thank Kitakyushu City workers and Mr. Hiroyuki Tajima and Mrs. Yuko Yano of the Kitakyushu Seaport and Airport Bureau for providing bioremediation data, Dr. Toshiro Yamashita of the Kitakyushu Environment Bureau for providing the data on nutrient loads, and Mrs. Akiko Terashi and Mrs. Yoko Kajiwara of the Institute of Environmental Sciences for skillful handling of the investigation of sessile animals. I especially thank the executive editor of “Estuaries in the World”, Dr. Jean-Paul Ducrotoy and the joint authors of this book, Dr. Tetsuo Yanagi and Dr. Keita Furukawa, for constructive comments on the manuscript.


  1. Central Environment Council, Ministry of the Environment (2010) Modalities of 7th water quality control by total quantity (Policy report), 66 p (in Japanese)Google Scholar
  2. Food and Agriculture Organization of the United Nations (2005) Review of the state of world marine fishery resources, FAO fisheries technical paper no.5. FAO, Rome, v+235 pGoogle Scholar
  3. Fukuoka Prefectural Fisheries Experiment Station (1933) Records on Dokai Bay, 136 p (in Japanese)Google Scholar
  4. Hamada K, Ueda N, Yamada M, Tada K, Montani S (2010) Seasonal changes in biochemical characteristics and vertical transport of particulate organic matter in hypertrophic Dokai Bay, Japan. Jpn Bull Coast Oceanogr 48:75–85 (in Japanese with English abstract and captions)Google Scholar
  5. Hamada K, Ueda N, Yamada M, Tada K, Montani S (2012) Decrease in anthropogenic nutrients and its effect on the C/N/P molar ratio of suspended particulate matter in hypertrophic Dokai Bay (Japan) in summer. J Oceanogr 68:173–182CrossRefGoogle Scholar
  6. Hashimoto S, Tada K (1997) Optical properties of seawater in Hiroshima Bay, Japan. Oceanogr Jpn 6:151–155 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  7. Heike KL, Flitner M, Urban ER Jr (2008) Coastal basins on the edge, Policy brief no. 7. UNESCO-SCOPE-UNEP, Paris, 6 pGoogle Scholar
  8. Higashi T, Yamada M, Montani S, Hirotani J, Yanagi T (1998) Development and characteristics of oxygen-deficient water mass in hypertrophic Dokai Bay, Japan. Nippon Suisan Gakkaishi 64:204–210 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  9. Hulburt EM, Guillard RRL (1968) The relationship of the distribution of the diatom Skeletonema tropicum to temperature. Ecology 49:337–339CrossRefGoogle Scholar
  10. Inoue K, Yanagi T, Montani S, Yamada M (1998) Variation of residual flow in Dokai Bay. Mem Fac Eng Ehime Univ 17:283–290 (in Japanese with English abstract and captions)Google Scholar
  11. Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health (2010) Scientific Assessment of Hypoxia in U.S. Coastal Waters, 105 p.
  12. Japan meteorological Agency (2012) Meteorological statistical information.
  13. Kajiwara Y, Yamada M (1997) Study on occurrence characteristics of sessile animals and classification of eutrophic level in Dokai Bay. J Jpn Soc Water Environ 20:185–192 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  14. Kohama T, Montani S, Kajiwara Y, Yamada M (2001) Population dynamics of sessile bivalves Mytilus galloprovincialis and Xenostrobus securis in a hyper eutrophic bay, Japan. Nippon Suisan Gakkaishi 67:664–671 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  15. Montani S, Kohama T, Tokunaga Y, Yamada M (1998) The development of environmental restoration technology utilizing ecological characteristics of filter feeding Bivalvia. Environ Sci 11:407–420 (in Japanese)Google Scholar
  16. Reid WV, Mooney HA, Cropper A, Capistrano D, Carpenter SR, Chopra K, Dasgupta P, Dietz T, Duraiappah AK, Hassan R, Kasperson R, Leemans R, May RM, McMichael T(AJ), Pingali P, Samper C, Scholes R, Watson RT, Zakri AH, Shidong Z, Ash NJ, Bennett E, Kumar P, Lee MJ, Raudsepp-Hearne C, Simons H, Thonell J, Zurek MB (2005) Ecosystems and human well-being: synthesis, millennium ecosystem assessment. Ed. by World Resources Institute, Island Press, Washington DC, p 137Google Scholar
  17. Sarno D, Kooistra WHCF, Medlin LK, Percopo I, Zingone A (2005) Diversity in the genus Skeletonema (Bacillariophyceae). II. An assessment of the taxonomy of S. costatum-like species with the description of four new species. J Phycol 41:151–176CrossRefGoogle Scholar
  18. Sarno D, Kooistra WHCF, Hargraves PE, Zingone A (2007) Diversity in the genus Skeletonema (Bacillariophyceae). III. Phylogenetic position and morphology of Skeletonema costatum and Skeletonema grevillei, with the description of Skeletonema ardens sp. Nov. J Phycol 43:156–170CrossRefGoogle Scholar
  19. Shimo S, Akimoto Y, Takahama H (2004) Review of the water quality effects on marine organisms. Rep Mar Ecol Res Inst 6:1–159 (in Japanese)Google Scholar
  20. Suksomjit M, Tada K, Funaki Y, Montani S, Yamada M, Harrison P (2009) Ammonium ion accelerates the growth rate of Skeletonema spp. in the phytoplankton assemblage in a heavily eutrophic embayment, Dokai Bay, Japan. La Mer 47:89–101Google Scholar
  21. Tada K, Ichimi K, Yokota HT, Yamada M, Montani S (2004) Why flagellates do not produce bloom in Dokai Bay, Japan, Japan. J Oceanogr 13:271–279 (in Japanese with English abstract and captions)Google Scholar
  22. Tada K, Ichimi K, Hamada K, Ueda N, Yamada M, Montani S (2007) Estuarine circulation and red tide outbreaks in Dokai Bay, Japan. Bull Coast Oceanogr 44:147–155 (in Japanese with English abstract and captions)Google Scholar
  23. Takao T, Okada T, Nakayama K, Furukawa K (2004) Seasonal variation of residence time of seawater in Tokyo Bay during 2002. Technical note of National Institute for Land and Infrastructure Management, 169, pp 1–78 (in Japanese)Google Scholar
  24. Tsutsumi H, Hamada K, Ueda N, Yamada M, Fujiki T, Nakamura H, Wada I, Tokuda T, Montani S (1998) Restoration of the sediment environment using Capitella sp. 1 Polychaete in the inner part of Dokai Bay. Environ Sci 11:421–429 (in Japanese)Google Scholar
  25. Ueda N, Tsutsumi H, Yamada M, Takeuchi R, Kido K (1994) Recovery of the marine bottom environment of a Japanese bay. Mar Pollut Bull 23:676–682CrossRefGoogle Scholar
  26. Ueda N, Tsutsumi H, Yamada M, Hanamoto K, Montani S (2000) Impacts of oxygen-deficient water on the macrobenthic fauna of Dokai Bay, and on adjacent intertidal flats, in Kitakyushu, Japan. Mar Pollut Bull 40:906–913CrossRefGoogle Scholar
  27. Unoki S, Kishino M (1977) Currents and water exchange in Tokyo Bay. Technical report of physical oceanography laboratory in Institute of Physical and Chemical Research 1, pp 1–86 (in Japanese)Google Scholar
  28. Working Group of Nature Restoration in Coastal Waters (2003) Handbook of nature restoration in coastal waters – design, technology and practice, vol 2, Tidal Flat edn. Gyosei, Tokyo, p. 31 (in Japanese)Google Scholar
  29. World Resources Institute (2012) Interactive map of Eutrophication & Hypoxia.
  30. Yamada M (2000) Chapter 12. Dokai Bay. In: Okada M, Peterson SA (eds) Water pollution control, policy and management: The Japanese experience. Gosei, Tokyo, pp 61–173Google Scholar
  31. Yamada M, Takeuchi R, Sueta S, Kido K, Yabumoto Y, Yoshida Y (1990) Recovery of aquatic animals in Dokai Bay, Northern Kyushu, Japan. Mar Pollut Bull 23:201–207CrossRefGoogle Scholar
  32. Yamada M, Higashi T, Hamada K, Ueda N, Eguchi N, Suzuki M (1998) Environmental improvement and management with an ecological environmental restoration method. Environ Sci 11:393–399 (in Japanese)Google Scholar
  33. Yamada M, Tanaka K, Yoshikawa H (2004) Present condition of aquatic environment and eco-remediation projects in Dokai Bay, Kitakyushu City. J Environ Lab Assoc 29:95–101 (in Japanese )Google Scholar
  34. Yamada M, Ueda N, Hanada Y (2005) Study on occurrence characteristics of seaweeds and eutrophic level of Dokai Bay, Kitakyushu City. J Environ Lab Assoc 30:252–258 (in Japanese)Google Scholar
  35. Yamada M, Katsuki E, Otsubo M, Hamada K, Ueda N, Montani S (2009) Survival strategy of tropical and subtropical marine diatom Skeletonema tropicum in temperate coastal small bay (Dokai Bay), Japan. Oceanogr Jpn 18:157–167 (in Japanese with English abstract and captions)Google Scholar
  36. Yamada M, Katsuki E, Otsubo M, Kawaguchi M, Ichimi K, Tada K, Harrison PJ (2010) Species diversity of the genus Skeletonema (Bacillariophyceae) in the industrial harbor Dokai Bay, Japan. J Oceanogr 66:755–771CrossRefGoogle Scholar
  37. Yamada M, Ueda N, Hamada K (2011) Changes in red tide occurrence and organisms responsible with declining eutrophic level in hyper-eutrophic Dokai Bay, Japan. Nippon Suisan Gakkaishi 77:647–655CrossRefGoogle Scholar
  38. Yanagi T (1997) Ecological modeling as tool for coastal zone management in Dokai Bay, Japan. J Mar Syst 13:123–136CrossRefGoogle Scholar
  39. Yanagi T (1998) The management of coastal waters and a numerical ecosystem model. Environ Sci 11:381–391 (in Japanese)Google Scholar
  40. Yanagi T, Takahashi S (1988) Response to freshwater discharge in Osaka Bay. Sea Sky 64:63–70 (in Japanese with English abstract and captions)Google Scholar
  41. Yanagi T, Yamada M (2000) Why red tides do not occur during winter in Dokai Bay, Japan. J Oceanogr 9:125–132 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  42. Yanagi T, Yamada M, Suzuki (1999) A challenge of water purification in Dokai Bay, Japan. Mar Pollut Bull 38:1063–1069Google Scholar
  43. Yanagi T, Yamada M, Nakajina M (2001) Comparison of eutrophication mechanisms of Dokai and Hakata bays. J Oceanogr 10:275–283 (in Japanese with English abstract and captions)CrossRefGoogle Scholar
  44. Zingone A, Percopo I, Sims PA, Sarno D (2005) Diversity in the genus Skeletonema (Bacillariophyceae). I. A reexamination of the type material of S. costatum with the description of S. grevillei sp. nov. J Phycol 41:140–150CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  1. 1.Fukuoka Woman’s UniversityFukuokaJapan

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