The use of indicator organisms to assess aquatic pollution following a motorway insecticide spill

Abstract

In April 1985, a transporter carrying the insecticide “Dursban” was involved in an accident near the M11/M25 interchange at Theydon Garnon, Essex. The resultant spill allowed a substantial amount of insecticide to enter “Brook House” Brook; a tributary of the River Roding. The macro-invertebrate benthos of the River Roding and two of its tributaries was sampled six months after the spill, at sites affected and unaffected by insecticide. Three distinct distribution responses by the fauna are identified and used to assess the environmental impact of the pollution. There was a sharp decrease in the type and number of organisms surviving in the affected parts of the river compared with unaffected regions. Re-population by some insecticide sensitive species was also observed. The effects of the spill are further investigated using hydrobiological indices.