Toxicity bioassays with periphyton communities: design of experimental streams

A method for conducting toxicity or enrichment bioassays using periphyton communities is described. Communities consisting of 35–55 species of diatoms are grown in plastic laboratory streams which may be operated as flowthrough or recirculating systems. Replication of community biomass, species composition and diversity in these streams is excellent, and the communities are easily sampled. The effects of nutrients, heavy metals, or other soluble toxins may be assayed in experiments lasting 3–5 weeks.