Shellfish toxicity

The mouse bioassay, an indirect assay, historically has been used to evaluate shellfish toxicity (especially for PSP). Other bioassay procedures have been developed but not generally applied for regulatory purposes (Schantz et al., 1958). The mouse bioassay involves intraperitoneal (i.p.)... 

Tester, P.A., Harmful marine phytoplankton and shellfish toxicity. Potential consequences of climate change, Ann. N.Y. Acad. ScL, 740, 69, 1994. 

The purpose of this paper is to examine our present knowledge of the cysts of the toxic Gonyaulax species to see whether these hypothetical considerations are valid representations of the actual roles cysts play in toxic dinoflagellate blooms and shellfish toxicity. 

In the years since these largely hypothetical roles were first proposed, considerable effort has gone into studies of cysts of toxic dinoflagellates. It is the objective of this paper to discuss the importance of cysts in shellfish toxicity episodes with respect to our present state of knowledge. It soon becomes clear from this type of exercise that despite significant progress in certain areas, many of the hypothetical links between cysts and shellfish toxicity remain probable but unverified. 

Distributional studies of cysts in sediments provide one indication of inoculum potential. For example, qualitative sediment surveys (i.e., presence vs. absence of cysts) demonstrated a close correlation between sites subject to shellfish toxicity and the presence of G. tamarensis cysts on Cape Cod (10, 14). This asso-... 

The most striking example is perhaps the 1972 New England red tide which caused extensive shellfish harvesting closures in Maine, New Hampshire and Massachusetts, the latter two states having no previous history of shellfish toxicity (32). In the more than 10 years since that event, Massachusetts has had PSP-related closures every year (14). 

Despite this progress, the evidence linking cysts to shellfish toxicity remains circumstantial and care should be exercised before attributing toxin increases to this mechanism. The major problem is that it has yet to be demonstrated that shellfish can remove toxin from cysts. The feeding studies mentioned earlier (which do not yet include scallops 35) indicate that many viable G. tamarensis cysts can be isolated from the fecal pellets of mussels and soft-shelled clams fed cyst suspensions. There is certainly some cyst mortality as well (Figure 5), but whether this is also associated with toxin retention by the shellfish has yet to be demonstrated. It is reasonable to expect that the assimilation of toxin from cysts will not be a highly efficient process. 

James, K. J, Eurey, A., Satake, M., and Yasumoto, T. 2000. Azaspiracid Poisoning (AZP) A new shellfish toxic syndrome in Europe. Abstract for the 9th International Conference on Algal Blooms, Tasmania, Australia. 

Cl Oceanic conditions are favorable, and there is a significant increase in toxic population and in bivalve shellfish toxicity levels. 

Human poisoning outbreaks by diarrheic toxins seem to be explosive, localized, and short-lived (holo-miantic outbreaks), given the very short incubation period (between 30 min and a few hours—3 h in DSP intoxication to 17 in AZA syndrome), which depends on the amount of toxin swallowed (shellfish toxic load and the amount of shellfish eaten), and the exposure to a common source. 

Sekiguchi, K., et al.. Occurrence of Protogonyaulax tamarensis and shellfish toxicity in Ofunato Bay from 1980-1986, In Red Tides Biology, Environmental Science, and Toxicology, Okaichi. et al., eds., Elsevier, New York, 399, 1989. 

The fluorimetric method of Bates and Rapoport [8], based on the oxidation of PSP toxins in alkaline conditions to form fluorescent derivatives, was incorporated into a detection method with the PSP toxins separated in a chromatographic column by Buckley et al. [17]. This method set the basis for the development of a high pressure liquid chromatography with postcolumn reaction system that was subsequently improved to achieve a better toxin separation and adequate sensitivity [18]. Sullivan et al. [ 19] evaluated its applicability to shellfish toxicity monitoring, by comparing the results obtained by the HPLC method and the standard Association of Official Analytical Chemists (AOAC) mouse bioassay. They found, in general, a good correlation between the two methods. However, Cl and C2 toxins could not be separated and individually quantified. Further improvements and modifications... 

Sudara, S., Tamiyavanich, S., and Wisessang, S., Red tide and paralytic shellfish poisoning phenomena in Thailand, in Toxic Red Tides and Shellfish Toxicity in Southeast Asia, White, A.W., Anraku, M., and Hooi, K., Eds., Southeast Asian Pisheries Development Center and the Ineternational Development Research Center, Singapore, 1984, 90. 

Fraga, S. et al., Influence of upweUing relaxation on dinoflagellates and shellfish toxicity in Rfa de Vigo, Spain, Estuar. Coast Shelf Sci., 27, 349, 1988. 

Dahl, E. and Johannessen, T., Relationship between occnrrence of Dinophysis species (Dinophiceae) and shellfish toxicity, Phycologia, 40, 223, 2001. 

A profile of the relative amounts of the various YTXs both in contaminated shellfish and in the producer organisms is essential to define two important issues (a) individuation of the YTXs that play a major role in the shellfish toxicity (b) metabolism of the accumulated toxins within the shellfish. These two topics are strictly related to the impact of YTXs contamination on public health and seafood resources. 

Rhodes, L., et al. Pseudo-nitzschia species isolated from New Zealand coastal waters domoic acid production in vitro and links with shellfish toxicity, in Harmful and Toxic Algal Blooms (ed. by Yasumoto, T., Oshima, Y. and Fukuyo, Y.) Intergovermental Oceanographic Commission of UNESCO, Paris, 1996, pp. 155-158. 

Cembella, A.D. and Krock, B., Biogeography of spirolides in Alexandrium ostenfeldii from the North Atlantic—implications for shellfish toxicity and seafood safety, in 6th International Conference on Molluscan Shellfish Safety Blenheim, New Zealand, 2007. 

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