Charles T. Corke

The effect of mercuric, cadmium, and nickel ion combinations on a blue-green alga

The response of Anabaena inaequalis towards combinations of mercuric, cadmium and nickel ion was dependent upon the order of metal addition and the actual metal concentrations involved. Mercuric and cadmium ions interacted synergistically towards photosynthesis (/sup 14/CO/sub 2/ uptake) and nitrogenase activity (acetylene reduction), but resulted in mixed synergism and antagonism towards growth, depending upon the actual metal concentrations used. Mercuric and nickel ions interacted in both a synergistic and antagonistic manner, depending on the metal concentrations used, towards growth and acetylene reduction, but evidenced a straight additive response towards photosynthesis. Nickel and cadmium ions interacted antagonistically towards all three assay criteria. Tri-metallic ion combinations resulted in antagonism towards growth and synergism towards photosynthesis and acetylene reduction. The pretreatment of cells with either cadmium or nickel ion protected against the toxicity of subsequently added mercuric ion. Similar results were obtained by pretreating cells with either mercuric or nickel ions prior to the addition of high levels of cadmium ion. It is proposed that the interactions observed are due to a competition between the metals for cellular binding sites. 26 references.

Toxicity of the insecticide permethrin and some degradation products towards algae and cyanobacteria

Abstract Toxic effects of the pyrethroid insecticide permethrin and ten of its degradation products were determined for the growth, photosynthesis and acetylene-reducing ability of two species of green algae and three species of cyanobacteria (blue-green) algae). Permethrin was relatively non-toxic in all systems, except for the growth of the cyanobacterium Anabaena inaequalis, where it had an EC50 of 1·5 to 5·0 ppm (μg ml−1). From two to five of the degradation products were significantly more toxic than permethrin. The most toxic metabolites were 3-phenoxybenzaldehyde and 3-phenoxybenzyl alcohol, followed by benzoic acid, 3-hydroxybenzoic acid and 3-phenoxybenzoic acid. The EC50 values of these compounds were as low as 1·4 ppm, although most were in the range 30 to 70 ppm for photosynthesis and acetylene reduction and 2 to 6 ppm for growth. The green algae were generally less sensitive than the cyanobacteria to these toxicants. Combinations of permethrin and selected metabolites were tested against A. inaequalis and yielded both synergistic, antagonistic and additive interaction responses, depending upon the actual test system.

Technique for identifying and minimizing solvent-pesticide interactions in bioassays

A simple, reliable, and accurate technique is presented for identifying and analyzing solvent-pesticide interactions in bioassays. This method used the solvent acetone, the fungicides metalaxyl and captan, and the fungiPythium ultimum, Sclerotinia homeocarpa, andPestalotia sp. Conclusions obtained were tested and verified by procedures specifically developed for both water-soluble and -insoluble pesticides. The interaction response observed with any given set of bioassay parameters was dependent upon both the acetone and fungicide concentrations. However, the method compensates for these discrepancies in interaction response and indicates the most suitable test parameters to employ in subsequent bioassays.

Interaction of permethrin with Daphnia magna in the presence and absence of particulate material

Abstract The 48-h LC50 of permethrin towards juvenile and adult Daphnia magna ranged from 0·2 to 0·6 μg litre−1. Permethrin also induced the adhesion of particulate material, including algae, bacteria and silica powder, onto various setate appendages of D. magna. This led to immobilisation of the daphnids and significantly earlier mortality in some systems containing algae. The adhesion phenomenon resulted from some effect of permethrin on D. magna, as opposed to an interaction with the particulate materials used. Algal adhesion to D. magna was also induced, to varying degrees, with diazinon, cypermethrin, methoxychlor and carbaryl.

The effect of cadmium ion on the growth, photosynthesis, and nitrogenase activity of Anabaenainaequalis

Abstract The growth of Anabaena inaequalis was significantly inhibited by Cd2+ concentrations greater than 0.02 ppm (μg/ml) and completely inhibited at 0.06 ppm (Day 12). Cadmium had no significant effect upon the lag phase of growth or the culture doubling time, but caused the retardation phase to arrive sooner. One ppm Cd2+ significantly inhibited the rates of both photosynthesis and acetylene reduction, by A . inaequalis , with complete inhibition at 4 and 20 ppm respectively. Cell sensitivity increased directly with exposure time. Cadmium caused some cell lysis of A . inaequalis and induced an increase in filament length, heterocyst frequency, and a loss of cellular contents from filament apical cells. The cellular abnormalities observed and the fact that toxicity increased with longer exposure times, suggested that metal toxicity resulted from effects of Cd2+ taken up by cells rather than Cd2+ at the cell surface.

Effect of acetone on the toxicity of atrazine towards photosynthesis in Anabaena.

The effect of acetone on the toxicity of atrazine towards photosynthesis in the blue-green algae Anabaena inaequalis, A. variabilis and A. cylindrica was investigated. The order of sensitivity to atrazine was A. inaequalis greater than A. variabilis greater than A. cylindrica. Acetone and atrazine interacted additively, antagonistically, and synergistically, depending upon the concentrations of acetone and atrazine used. The EC50 of atrazine towards photosynthesis was dependent upon the type of solvent-pesticide interaction.