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Shimada H.,Central Fisheries Research Institute of Hokkaido Research Organization | Sawada M.,Central Fisheries Research Institute of Hokkaido Research Organization | Tanaka I.,Central Fisheries Research Institute of Hokkaido Research Organization | Asami H.,Central Fisheries Research Institute of Hokkaido Research Organization | Fukamachi Y.,Hokkaido University
Fisheries Science | Year: 2012

To design a method for predicting outbreaks of paralytic shellfish poisoning (PSP) in scallop fishing grounds, the relationship between the distribution of the toxic dinoflagellate Alexandrium tamarense and the dynamics of the Soya Warm Current (SWC) was examined in the Okhotsk Sea off Hokkaido. Surveys were conducted from May to June to clarify the transportation mechanism of A. tamarense from the oceanic area to the coastal area. The sea-level difference (SLD) between Wakkanai and Abashiri was monitored as an index of the strength of the SWC southeastward flow in an alongshore belt to examine the possible occurrence of A. tamarense in the coastal area during temporal weakening of the SWC. A bottom-mounted acoustic Doppler current profiler (ADCP) was used for direct observations of the SWC. The results indicated that PSP occurred when low-salinity water contaminated with A. tamarense extended to the coast during temporal weakening of the SWC due to a decrease of the SLD. Our results strongly indicate that predictions can be realized by monitoring the decrease of SLD as an index of temporal weakening of the SWC after surveys of the distribution of A. tamarense in the oceanic area before the period of PSP occurrence. © 2012 The Japanese Society of Fisheries Science.


Shimada H.,Central Fisheries Research Institute of Hokkaido Research Organization | Motylkova I.V.,Sakhalin Scientific Research Institute of Fisheries and Oceanography | Mogilnikova T.A.,Sakhalin Scientific Research Institute of Fisheries and Oceanography | Mikami K.,Central Fisheries Research Institute of Hokkaido Research Organization | Kimura M.,Central Fisheries Research Institute of Hokkaido Research Organization
Plankton and Benthos Research | Year: 2011

To evaluate the variations in the toxin profiles of Alexandrium tamarense (Dinophyceae) from Hokkaido and southern Sakhalin, paralytic shellfish poison of 103 culture strains obtained from six areas (Funka Bay, Tomakomai, Urakawa, Akkeshi, Okhotsk Sea and Aniva Bay) was analyzed using high performance liquid chromatographyfluorescent detection. All of the strains, except for two culture strains, were classified by a hierarchical cluster analysis into clusters in which the strains had almost the same toxin composition as found in previous studies (major toxins: C2, gonyautoxin 4, neosaxitoxin and gonyautoxin 3). On the other hand, cellular toxin contents of the culture strains varied from 1 to 1,128 fmol cell -1 and the cellular toxin content (y fmol cell -1) was inversely proportional to the cell density (x cellsmL -1 (y=9942.2x_0.448, Spearman's rank correlation coefficient: r s=0.539, p<0.01). It can be concluded that the toxin compositions of A. tamarense are almost the same in Hokkaido and southern Sakhalin, and hightoxicity blooms of A. tamarense as usually found possibly occur in the natural environment at low cell densities (10 -2-10 -2 cellsmL -1).© The Plankton Society of Japan.

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