A method for predicting the occurrence of paralytic shellfish poisoning along the coast of Hokkaido in the Okhotsk Sea in summer

Shimada, Hiroshi; Sawada, Mayumi; Tanaka, Iori; Asami, Hiroki; Fukamachi, Yasushi

doi:10.1007/s12562-012-0513-5

Cited by 12 publications

(9 citation statements)

References 25 publications

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“…In previous studies, the sea level difference between Wakkanai and Abashiri (e.g., Aota 1975;Shimada et al 2012) predicts the SWC flow. However, SSH along the baroclinic jet axis away from the Soya Strait is almost uniform in the along-isobath direction (Fig.…”

Section: Summary and Discussionmentioning

confidence: 87%

“…2), the strong horizontal density gradient of approximately 25-26σ θ , which is located 10-20 km offshore from the coast, causes a baroclinic jet with a velocity exceeding 1 m s −1 near the surface (Fukamachi et al 2008). Since the SWC region is a commercial fishing ground in Japan (e.g., Shimada et al 2012), its hydrographic conditions have stimulated much interest in terms of not only oceanography but also in relation to the fisheries and seafood industries.…”

Section: Introductionmentioning

confidence: 99%

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Buoyancy shutdown process for the development of the baroclinic jet structure of the Soya Warm Current during summer

2018

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The Soya Warm Current (SWC), which is the coastal current along the northeastern part of Hokkaido, Japan, has a notable baroclinic jet structure during summer. This study addresses the formation mechanism of the baroclinic jet by analyzing a realistic numerical model and conducting its sensitivity experiment. The key process is the interaction between the seasonal thermocline and the bottom Ekman layer on the slope off the northeastern coast of Hokkaido; the bottom Ekman transport causes subduction of the warm seasonal thermocline water below the cold lower-layer water, so the bottom mixed layer develops with a remarkable cross-isobath density gradient. Consequently, the buoyancy transport vanishes as a result of the thermal wind balance in the mixed layer. The SWC area is divided into two regions during summer: upstream, the adjustment toward the buoyancy shutdown is in progress; downstream, the buoyancy shutdown occurs. The buoyancy shutdown theory assesses the bottom-mixed-layer thickness to be 50 m, consistent with observations and our numerical results. The seasonal thermocline from June to September is strong enough to establish the dominance of the buoyancy shutdown process over the frictional spindown.

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Section: Summary and Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Buoyancy shutdown process for the development of the baroclinic jet structure of the Soya Warm Current during summer

2018

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“…In western Canada and northern Japan, toxin contaminations of shellfish, such as seashore mussels and seabed scallops, typically exceed regulatory levels when A . tamarense appears at densities over 100–1,000 cells L -1 [ 17 , 18 ]. The maximum A .…”

Section: Discussionmentioning

confidence: 99%

Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005

et al. 2017

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The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100–1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate) were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will increase the frequency and scale of toxic blooms and the toxin contamination of plankton feeders. This poses serious threats to humans and the marine ecosystem.

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“…To provide an early warning for the fisheries industry and avoid adverse effects on human health, monitoring the temporal variation in the abundance of Alexandrium spp. has become indispensable (Itakura et al, 2002;Weise et al, 2002;Anderson et al, 2005;Shimada et al, 2012;Laanaia et al, 2013;Yamamoto et al, 2013;. In this study, A. catenella sensu Fraga et al (2015) was monitored in relation to plankton biodiversity and environmental parameters as this toxic dinoflagellate is present in all Japanese coastal waters (Fukuyo, 1985;Sekiguchi et al, 1986;Uchida et al, 1980;Yamamoto et al, 2009) and has become a conspicuous species in southwestern Japan since 1990s (Yamamoto and Yamasaki, 1996;Kotani et al, 1998).…”

Section: Introductionmentioning

confidence: 97%

Monitoring of the toxic dinoflagellate Alexandrium catenella in Osaka Bay, Japan using a massively parallel sequencing (MPS)-based technique

Nagai

Chen

Kawakami³

et al. 2019

Harmful Algae

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A B S T R A C TSince 2002, blooms of Alexandrium catenella sensu Fraga et al. (2015) and paralytic shellfish toxicity events have occurred almost yearly in Osaka Bay, Japan. To better understand the triggers for reoccurring A. catenella blooms in Osaka Bay, phytoplankton community was monitored during the spring seasons of 2012-2015. Monitoring was performed using massively parallel sequencing (MPS)-based technique on amplicon sequences of the 18S rRNA gene. Dense blooms of A. catenella occurred every year except in 2012, however, there was no significant correlation with the environmental parameters investigated. Plankton community diversity decreased before and middle of the A. catenella blooms, suggesting that the decline in diversity could be an indicator for the bloom occurrence. The yearly abundance pattern of A. catenella cells obtained by morphology-based counting coincided with the relative sequence abundances, which supports the effectiveness of MPS-based phytoplankton monitoring.

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A method for predicting the occurrence of paralytic shellfish poisoning along the coast of Hokkaido in the Okhotsk Sea in summer

Abstract: 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

Cited by 12 publications

References 25 publications

Buoyancy shutdown process for the development of the baroclinic jet structure of the Soya Warm Current during summer

Buoyancy shutdown process for the development of the baroclinic jet structure of the Soya Warm Current during summer

Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005

Monitoring of the toxic dinoflagellate Alexandrium catenella in Osaka Bay, Japan using a massively parallel sequencing (MPS)-based technique

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