MAP Technical Reports Series No. 106 UNEP

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In regard to considering the harmful effects of algal blooms, it was suggested that toxic
algal blooms fall into three categories: eutrophication dependent on a large number of cells;
associated with a large number of cells but not with anthropogenic nutrient enrichment of coastal
waters; toxicity associated with low cell numbers (as for Dinophysis blooms or Alexandrium
cystes) (Smayda, 1990).
It is important to recognize that the various seafood toxin syndromes depend not only
on natural nutrient enrichment of coastal waters or anthropogenic or due to agricultural runoff,
aquaculture (anthropogenic eutrophication), but also on the dispersion of the resting cyst of
toxigenic dinoflagellates by dredging, discharge of ship ballast water, or transplanting of shellfish.
In this chapter the attention is paid to PSP and DSP (the most widespread
biointoxication from toxic marine dinoflagellates in the world and for which the EC is proposing
health legislation such as tolerance limits and methods for official analysis) since these are
today the known seafood toxin syndromes in the Mediterranean sea. In this chapter are also
considered marine algae potentially toxic for seafoods and for respiratory or cutaneous
symptoms of poisoning in the Mediterranean sea (Prorocentrum minimum and venerupin
poisoning; Nitzschia spp. and ASP; Chlorophyta and Rhodophyta toxins; Gymnodinium spp.
blooms; marine Cyanophyta blooms); and general effects on eutrophication, bacteria and human
health.
From data currently available on PSP, DSP and other biointoxications attention is paid,
on the basis of available literature, to: organisms producing toxins, chemistry of components,
occurrence in the world, occurrence in Mediterranean, compromised seafood, detoxification in
bivalve molluscs, methods of analysis, human intoxication and mechanism of action, tolerance
levels and remark on safety. References documentation (general) and references cited are also
reported.
7.2 The known seafood toxin syndromes in the Mediterranean sea
7.2.1 Paralytic Shellfish Poisoning (PSP)
In certain coastal areas oysters, mussels, clams and gastropod molluscs as well as
some crustaceans and fish become toxic sporadically or constantly in some month of the year
and produce in man a neurotoxic syndrome known as "paralytic shellfish poisoning" (PSP)
(Shimizu, 1979; Steidinger and Baden, 1984).
7.2.1.1 PSP-producing or potentially toxic dinoflagellates
In the sea world. The water-soluble toxins of PSP type (a family of closely related toxins
known as saxitoxins) are produced in temperate water by members of the genus Alexandrium
(Alam et al., 1979; Taylor, 1984), also known as Gonyaulax or Protogonyaulax, including: A.
tamarensis (A. excavata), A. catenella, A. acatenella, A. fundyense, A. minutum and A.
cohorticula. The dinoflagellate recognized to be source of PSP toxins in tropical waters is
Pyrodinium bahamense var. compressa (Taylor, 1984). Other dinoflagellates reported to
produce PSP include Gymnodinium catenatum and probably Cochlodinium spp. (Krogh, 1989).
G. catenatum collected for first time in Galician rias (Spain) in October 1976 and also in 1991
produces PSP toxins, but not brevetoxins (Estrada et al., 1984). G. catenatum has a wide
geographic distribution (Pacific coast of America, Japan, Australia, and the Atlantic coast of
Spain) (Campos et al., 1982; Hallegraeff and Summer, 1986; Hallegraeff et al., 1987; Hallegraeff
et al., 1988) and also in the Mediterranean coast of Spain (Bravo et