Toxicity of blue-green algae in livestock

Abstract

Blue-green algae (Phylum Cyanophyta) occur in nearly every pond, stream, and lake in Oklahoma. Under proper conditions in ponds or lakes certain toxic species may accumulate in such quantities that a hazard to livestock develops. At least one case of algae toxicity has been confirmed at the Oklahoma Animal Disease Diagnostic Laboratory since the summer of 1977.

Algae accumulate from population explosions called "water blooms" or simply "blooms". A bloom usually contains only one or 2 species. The algae will accumulate to the point of tinting the water bright breen or covering the surface with a thick gelatinous mass. When these blooms are dominated by a toxic species of blue-green algae poisonings may occur. Poisoning may occur during a bloom from species producing an exotoxin or immediately following a bloom when dying cells release their endotoxins. Toxic conditions may be very short lived so samples of water should be taken and refrigerated at the first sign of animal distress.

There are five genera of blue-green algae that are universally accepted as toxic or capable of producing toxins. They are Microcystis, Nodularia, Anabaena, Aphanizomenon, Gloeatrichia. Microsystis is generally the most noxious and is the only genus known to produce an exotoxin. Along with Anabaena and Aphanizomenon it is the most common form of toxic algae in substantiated cases of blue-green algae poisoning. All toxic algae contain pseudovacuoles which tend to bouy them to the surface.