MAP Technical Reports Series No. 106 UNEP

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Initially, there is a reversible specific damage to gill tissues, consisting of the loss of
their selective permeability, followed by a second stage leading to mortality, as a response of
sensitized fish to non specific toxicants present in the environment in concentrations subletal
to normal fish (Shilo, 1967).
The studies on the purification and analysis of Prymnesium preparations have shown
that the active principle (prymnesin) is a glycolipid of high molecular weight (23,000 ± 1,800). The
skeleton of its structure is a polysaccharide containing about 100 hexose molecules composed
of glucose, mannose and galactose in a 2:1:1 ratio. In this polysaccharide 26 hydroxyl groups
are esterified by four long chain fatty acids.
The various biological activities connected with prymnesin probably result from
interactions with the cell membrane. It is presumed that prymnesin is attached to biological
membranes and the resulting rearrangement of the membrane makes it permeable and loose.
Ulitzur and Shilo (1970) using a different separation technique, obtained a second toxin
called "toxin B" which had 15 amino acids and a number of unidentified fatty acids. In contrast
to prymnesin, toxin B resembled a proteolipid. It had six haemolytic factors.
Genus CHRYSOCHROMULINA Lackey
Also, the extensive flowering of the Chrysochromulina polylepis in 1988, along the
coasts of Denmark, Sweden and Norway, which reached a maximum concentration of 50-100
million cells/litre, and which caused massive invertebrate and fish mortality both in the natural
state and in farming, has opened up new health and economic problems for the European seas
(Undertal et al., 1989). It must be noted that blooms of the C. polylepis are considered today to
be an example of marked nutrient increase on coastal areas and therefore one of the
characteristic parameters of anthropogenic eutrophication. The ichthyotoxins produced by this
prymnesiomonadine is a glycolipid: monoacyl-digalactosylglycerol, whose fatty acid is a C 18:5
or 20:5 (1-acyl-3- digalactosylglycerol) (Yasumoto et al., 1990).
6.1.3 Raphidophyceae (Chloromonadophyceae)
Genus CHATTONELLA
Some chloromonadines also produce ichthyotoxins. Chattonella antiqua and C. marina
are responsible for damage along the Japanese coast. It has been considered that their
ichthyotoxic action can be due to the polyunsaturated fatty acids (Lassus, 1988).
The chloromonadines too, constitute for the European seas, and in particular the
Mediterranean potentially ichthyotoxic phytoplanktons. As far as Chattonella subsalsa is
concerned, in the 1960s this species was responsible for a fish kill along the Mediterranean
coasts of France and Spain and for a bloom of 2,000,000 cells, in the Port of Algiers in 1956
(Hollande and Enjumet, 1957) and in the Port of Barcelona in 1968 (Margalef, 1968), and
similarly in the Bay of Villefranche-sur-mer in 1961 (Tregouboff, 1962).
6.1.4 Dictyochophyceae (= Silicoflagellates)
Genus DICTYOCHA
The number of species of silicoflagellates in existence which are toxic to fish is
probably only three. These organisms were abundant in the secondary era. The first cases