Algal Toxins

Abstract

This chapter focuses on the algae responsible for producing toxins. These are found in three of the eight divisions which make up the algae. These are the Chrysophyta (class Prymnesiophyceae), Cyanophyta (cyanobacteria or blue-green algae), and the Pyrrhophyta. In the Chrysophyta, the toxic species is the flagellated unicellular Prymnesium paruum. In the Cyanophyta, both marine and freshwater toxic species are found. Marine toxic forms are in the filamentous genera Lyngbya, Schizothrix, and Oscillatoria. Toxins produced are of the type responsible for the contact dermatitis called “swimmers itch”. Toxic freshwater cyanobacteria include the unicellular colonial Microcystis and the filamentous Anabaena, Aphanizomenon, Nodularia, and Oscillatoria. These freshwater algae can form thick surface accumulations of cells as the water bloom develops within the water body. They are responsible for sporadic but widespread outbreaks of wild and domestic animal illness or death. They are also implicated in human poisonings in certain municipal and recreational water supplies. Two major disease types are recognized: first is paralytic shellfish poisoning and second is called ciguatera seafood poisoning. The chapter presents isolation, characterization, and toxinology of algal toxins, and analyzes the environmental role of algal toxins. Whatever the role for algal toxins, it is evident that (1) they are diverse groups of physiologically potent secondary chemicals that are more chemically related to higher plant toxins than they are to bacterial or animal toxins; (2) their production should not be considered fortuitous or accidental but rather part of evolutionary processes by which the organisms have adapted to particular needs and requirements of their environment; and (3) studies on production of the toxins including possible environmental and genetic influences will serve to aid an overall understanding of secondary chemical production. © 1986 Academic Press Inc.