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Activities of five liver enzymes (acid and alkaline phosphatase, catalase, xanthine oxidase, and ribonuclease) from Fundulus heteroclitus surviving exposure to 96-hr TLm concentrations of salts of six metals (lead, copper, mercury, beryllium, cadmium, and silver) differed markedly from those of unexposed fish. Changes in enzyme activity produced by the exposures were not necessarily the same in magnitude or direction as those observed when the salts were introduced directly into the enzyme preparations. It is proposed that changes in liver enzyme activity may be useful as a kind of biochemical autopsy tool for diagnosing sublethal metal poisoning in fish.

Three rapid marine toxicity tests were evaluated to determine their potential usefulness in a toxicity testing program: early embryo growth test and sperm cell toxicity test, both using the sea urchin Arbacia punctulata, and Microtox. Toxicity values (EC50s) were derived for eight organic chemicals and five metals using each system. Results were compared with LC50 values for the same chemicals from standard aquatic tests with Pimephales romelas and Daphnia magna and for the metals with Menidia menidia and Mysidopsis bahia. The EC50 values for the sea urchin early embryo growth test for organics and the LC50 values for fish and crustaceans for organics and metals with which the rapid tests were compared were from the literature. For organic chemicals, EC50s from rapid tests closely approximated LC50s and toxicity rankings, except that the sperm cell test was particularly sensitive to 2,4‐pentanedione and 2‐methyl‐2,4‐pentanediol. EC50s for metals were generally comparable with each other and with other tests using embryo and sperm of other sea urchins and oysters but not with LC50s for Mysidopsis and Menidia. These results indicate the potential value of rapid tests to screen and rank substances for toxicity. Additional information on the usefulness of these tests will be gained through continuing comparisons using a broad spectrum of single substances and complex mixtures with varying modes of action.

Toxins were isolated from the freshwater blue-green alga Aphanizomenon flos-aquae. The toxic fractions were characterized by paper and thin-layer chromatography, isolation characteristics, infrared spectra, physiological activity, and reactivity with specific color reagents. The toxic fractions appear to be similar, if not identical, to saxitoxin (paralytic shellfish toxin), which is produced by the marine dinoflagellate Gonyaulax catenella.