Vegetative survival, akinete and zoosporangium formation and germination in some selected algae as affected by nutrients, pH, metals, and pesticides.

Lack of nitrogen, phosphorus, or all nutrients, extremes of pH (< 4, > 11), presence of 'heavy' metals (Co, Cu, Zn, Hg, Pb; 0.5-10 ppm) or pesticides (carbofuran, 2,4-D, dithane, phorate, or bavistin; 1-50 ppm) decreased to various extent or completely inhibited the survival or vegetative cells in all studied algae. The formation of akinetes, their viability and germination in Anabaena iyengarii, Westiellopsis prolifica, Nostochopsis lobatus and Pithophora oedogonia and the formation of zoosporangia, their viability, and the germination of zoospores in Cladophora glomerata and Rhizoclonium hieroglyphicum was affected. The formation of viable akinetes or zoosporangia was shown to be directly linked with vegetative cell survival and growth; it could not be induced by any chemical stress imposed.