Chemical analysis, although valuable and necessary, does not provide all the information required in pollution assessment. Biological studies are of particular value in permitting a realistic assessment of pollution and they cover a wide range of possibilities. The present manual makes only cursory reference to the techniques used to study the sublethal toxic effects at the “individual” level of organisation or below since it is devoted to biological studies at community level and especially to the use of benthos. It describes how a benthic sampling programme should be designed so that the data collected can be best interpreted and evaluated.
