Effect of sewage effluents on germination of three marine brown algal macrophytes

Inhibition of germination of zygotes of the fucoid macroalgae Hormosira banksii and Phyllospora comosa and zoospores of the laminarian Macrocystis angustifolia was used as an end-point to assess the toxicity of three sewage effluents of differing quality. For each species, between-assay variation was low and results of tests with the reference toxicant 2,4-dichlorophenoxyacetic acid suggested that results are reproducible, especially in P. comosa. Each species showed a greater sensitivity to primary-treated effluent than to secondary-treated effluent, and higher variability in response to the primary effluent. High variation in response for each species when exposed to the primary effluent (compared with that for the secondary effluent) is presumably indicative of variation in quality of the primary effluent. The capacity to reproduce these assays, the sensitivity of species employed, and the ecological relevance of germination as a toxicological end-point suggest that germination tests of this nature may be useful in biological testing of effluent quality at discharge sites in south-eastern Australia.