From the numerous and diverse studies of pollution effects on marine molluscs, a few species and techniques have emerged as suitable for routine effluent toxicity measurement. As marine mollusc toxicity testing evolves from research to routine application, it has become increasingly important to determine the reliability and repeatability of toxicity measurement, and to evaluate the degree of protection that regulations based on such measures provide for organisms that inhabit receiving waters. This paper reviews recent studies of standard mollusc protocols to estimate their inter- and intralaboratory precision, relative sensitivity, and the degree to which they currently meet proposed criteria for toxicity tests that can be used effectively in regulating effluent discharges.

Experiments were conducted to evaluate temporal and geographic variation in sensitivity of microscopic stages of giant kelp Macrocystis pyrifera to copper. Spores from kelp sporophylls collected from different locations and at different times of the year were exposed to series of copper concentrations following a standard toxicity test procedure. After 48 h static exposures, toxicity was determined by measuring 2 test endpoints: germination success and growth of germination tubes. The sensitivity of these endpoints to copper was also compared with the sensitivity of longer-term reproductive endpoints: sporophyte production and sporophyte growth. No significant differences in response to copper were found among spores from different collection sites. Variability between 4 tests conducted quarterly throughout the year was greater than that between 3 tests done consecutively within 1 mo, indicating temporal variability in response to copper. Long-term reproductive endpoints were more sensitive to copper than were short-term vegetative endpoints, with No Observed Effect Concentrations of < 10 pg 1-' for sporophyte production, 10 yg 1-I for sporophyte growth, 10 yg 1-' for germ-tube growth, and 50 yg 1-I for germination inhibition.

Algal toxicity testing is not new, but only within the past few years have data from such testing been used to help set standards for allowable contamination. Early toxicity testing with marine algae used a few planktonic species with inhibition of growth as the primary endpoint. Results obtained from these algal tests established a reputation for insen-sitivity to toxicants relative to animals. Work with vegetative growth of marine seaweeds from intertidal areas also led to conclusions of insensitivity to toxicants. Based on this reputation, marine algae as a group have been considered nonessential for assessing effects of pollutants on the marine environment. Within the past five years, tests with different species of microalgae and reproductive tests with marine macroalgae have come into wider use. These new species and test method endpoints have shown that plants can be more sensitive to toxicants than some of the most sensitive marine animals. It has been proposed recently that the saltwater “Criterion Continuous Concentration” for water quality criteria documents for thallium and acenaphthene be set with reproductive data from the kelp, Laminaria saccharina; which was the most chronically sensitive species tested for both chemicals. Plant tests also are now being required for some National Pollutant Discharge Elimination System permits for the marine environment.

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