Repercussions of the Great East Japan Earthquake tsunami on ellipsoidal Alexandrium cysts (Dinophyceae) in Ofunato Bay, Japan. (April 2018)

• Record Type: Journal Article
• Authors: Matsuoka, Kazumi; Ikeda, Yuri; Kaga, Shinnosuke; Kaga, Yoshimasa; Ogata, Takehiko
• Is Part Of: Marine environmental research. Volume 135(2018)
• Page Start: 123
• Page End: 135
• Publication Date: 2018-04
• Subjects: Alexandrium cyst -- Great East Japan Earthquake -- Ofunato Bay -- Sediment -- Paralytic shellfish poisoning -- Chilean tsunami; Marine pollution -- Environmental aspects -- Periodicals; Marine ecology -- Periodicals; Mer -- Pollution -- Aspect de l'environnement -- Périodiques; Écologie marine -- Périodiques; Electronic journals; 577.705
• DOI: 10.1016/j.marenvres.2018.01.001
• Languages: English
• ISSNs: 0141-1136

Abstract

Abstract: Shellfish aquaculture in Ofunato Bay, Northeast Japan, was seriously damaged by a tsunami generated by the Great East Japan Earthquake, March 11th, 2011, accompanied by paralytic shellfish poisoning (PSP) outbreaks caused by Alexandrium tamarense (Dinophyceae). To understand longer future trends of PSP, an investigation was made of the historical occurrence and causes of Alexandrium outbreaks after the tsunami. Vertical distributions of Alexandrium cysts in two sediment-cores from Ofunato Bay revealed that the sediments above ca. 25 cm were eroded, re-suspended and re-deposited, and they included unusually abundant Alexandrium cysts. This abundance of cysts was due to re-deposition of older sediments by the tsunami. The first Ofunato Bay PSP incident was in 1961 after the Chilean Earthquake tsunami and was probably caused by similar unusual blooms of Alexandrium germinated from older sediments as the Great East Japan tsunami, together with nutrient enrichment because of population increase at the start of shellfish aquaculture. Highlights: The ca. upper 25 cm sediments of Ofunato Bay were re-deposited by the tsunami of the 2011 Great East Japan Earthquake. The maximum density of ellipsoidal Alexandrium cysts at the 6–7 cm depth was due to the re-suspension of older sediments. The first PSP incident on 1961 in this bay was resulted from the similar phenomena after the Chilean tsunami in 1960.