The use of barley-straw to control general and blue-green algal growth in a Derbyshire reservoir

The presence of rotting barley-straw at approximately 50 g m−3 in a disused water supply reservoir appeared to significantly reduce both the general phytoplankton productivity and the cyanobacterial dominance. Algal control mechanisms were not implemented via nutrient removal but appeared in part biological by encouraging phytoplankton grazing organisms and mainly chemical by releasing relevant levels of known phytotoxic compounds near to the decomposing straw. No short term deleterious environmental impact was recorded in the receiving watercourses. Preliminary chemical characterisation of straw leachate is discussed with respect to known phytotoxic agents from the limited toxicological literature.