Prediction of on-site depuration of paralytic shellfish poisoning toxins accumulated in the scallop Patinopecten yessoensis of Ofunato Bay, Japan

Shinnosuke Kaga,Takehiko Ogata,Shigeru Sato,Kimiaki Naiki,Yoshimasa Kaga,Shiho Watanabe,Yuichiro Yamada

doi:10.1007/s12562-015-0891-6

Shinnosuke Kaga, Takehiko Ogata + Show 5 more

Open Access

https://doi.org/10.1007/s12562-015-0891-6

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Abstract

In this paper, we present a decay equation for paralytic shellfish poisoning (PSP) toxins using long-term field data spanning more than 10 years in order to predict the detoxification period for the scallop Patinopecten yessoensis in Ofunato Bay, Japan. From the data, we obtained the date of maximum toxicity in the digestive gland (DG) of the scallop and then the date of detoxification. Next, we performed linear regression analysis between loge-toxicities and days after the maximum toxicity level for each study year. Toxicity declined at a rate of 1.5 %/day, and a period of 3–9 months was required for the scallop to achieve a toxicity level of 20 mouse units (MU)/g DG tissue, which is a critical level for determining monitoring frequency and area of scallop toxicity. We then estimated the number of days needed to reach 20 MU/g DG tissue (t 20) using the equations obtained by the above-mentioned analysis, and we performed another linear regression analysis between the loge (maximum toxicity) and t 20 for each year. The difference between the actual and predicted detoxification time ranged from −16 to 18 days. We conclude that these equations can be used to predict the depuration of PSP toxins from scallops in Ofunato Bay.

Highlights

Bivalves exposed to blooms producing paralytic shellfish poisoning (PSP) toxins vary markedly in their ability to detoxify these accumulated toxins [1]
After the Great East Japan Earthquake in 2011, accumulation of PSP toxins through the ingestion of A. tamarense was reported in the mussel M. galloprovincialis, the scallop P. yessoensis, and other species in Ofunato Bay [10, 11]; in 2013, a study found that a period of 9 months was needed for PSP toxin levels in the scallops to decrease from the maximum to 20 mouse units (MU)/g digestive gland (DG) tissue [11]
Retoxification based on the presence of A. tamarense after maximum toxicity levels were reached in scallops

Summary

Introduction

Bivalves exposed to blooms producing paralytic shellfish poisoning (PSP) toxins vary markedly in their ability to detoxify these accumulated toxins [1]. After the Great East Japan Earthquake in 2011, accumulation of PSP toxins through the ingestion of A. tamarense was reported in the mussel M. galloprovincialis, the scallop P. yessoensis, and other species in Ofunato Bay [10, 11]; in 2013, a study found that a period of 9 months was needed for PSP toxin levels in the scallops to decrease from the maximum to 20 MU/g digestive gland (DG) tissue [11] In light of these issues, scallop farming is being replaced by oyster farming, owing to the lower toxicity levels and higher detoxification rates in oysters. In 2013, the production volume and production value of scallops in Ofunato Bay were 90 tons and 25 million yen, respectively, a reduction of 82 % (407 tons and 113 million yen) compared to those in 2009 [12, 13]

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