An experimental approach to the determinants of biological water quality.

A case is presented for the use of experimental bioassay techniques to detect and measure variations in water quality in the marine environment by exposing suitable organisms in the laboratory to water samples collected in the field. A technique is described which was developed for this purpose with the use of a clonal hydroid; preliminary results from Swansea Bay show that it is sensitive to the variations in water quality that occur there. Chemical techniques are being developed for use in conjunction with such bioassays to identify the kinds of contaminants responsible for a detected effect, and some preliminary experiments suggest that divalent metals and the volatile constituents of hydrocarbons can be removed selectively from sea water.