Abstract
Bioassay techniques for testing treated waste water (sewage effluent) and toxic chemicals in seawater by monitoring the growth of seaweed were reviewed in this paper. Waste waters have been tested by seaweeds were classified into indusrial waste water, sewage effluent, night-soil effluent, antifouling chemicals in sea-water and other toxic chemicals in seawater. Porphyra tenera or yezoensis (nori) in Japan and Macrocystis pyrifera (giant kelp) have mostly been used for biological testing in past researches. P. tenera or yezoensis and M. pyrifera were chosen for toxicity bioassays of treated sewage effluent due to their biological and socio-economic effectiveness and significances. Bioassay techniques such as the life stages of specimens and test periods required, methods of detecting adverse effects of effluent on specimens, culture methods, culture conditions, culture media and effluent sampling times were described. Chemical substances which promote or hinder the growth of seaweeds are contained in the treated sewage effluent and chemical substances and their concentrations change daily and weekly. Lower salinity intensify the adverse effects of effluent on growth of seaweeds. Therfore, variables such as effluent concentration, salinity of culture media and dayly and weekly changes of effluent must taken into account. It was clarified by the proposed bioassay techniques that the strongest toxic substance on the growth of P. yezoensis was monochloramine resulting from chlorinated sewage effluent. P. yezoensis is considered to be the appropriate seaweed for toxicity bioassay of treated sewage effluent for the biological and socio-economic effectiveness and significances in Japan.
