An improved epilithon sampler and its evaluation in two acid lakes

An improved epilithon sampler is described which allows for in situ substrate sampling and multiple washing of the sample surface. Good sample replication indicates minimal loss of detached epilithic material during collection. The sampler is evaluated in two acid lakes between which a significant difference in both the total cover of epilithic material and in diatom standing crop is demonstrated. The relevance of quantitative measurements of diatom epilithon abundance to palaeolimnology is emphasized.