The use of aquatic macrophyte ecotoxicological assays in monitoring coastal effluent discharges in southern Australia

Germination inhibition of zoospores of the aquatic, brown algal macrophyte Ecklonia radiata was employed to assess the toxicity of sewage effluents un der short to long term exposure and under modified salinity conditions. The rate of germination inhibition was determined for exposure times between 2 and 48 h in salinity modified and unmodified regimes and under reduced sal inity conditions alone. The results indicated that rate of germination inhi bition increased with duration of exposure to sewage effluents and to salin ity reduction alone, and that response to the effluents may be enhanced und er conditions of reduced salinity. Whilst the effect of primary treated eff luent was primarily that of toxicity, secondary treated effluent effects ap peared to be primarily that of reduced salinity although at a greater rate than would be expected for salinity reduction alone. The assay is suggested to provide a mechanism for monitoring sewage efflueut quality and to monit or potential impacts of sewage effluent discharge on kelp communities in so uthern Australia. (C) 1999 Elsevier Science Ltd. All rights reserved.