The use of tubificidae in a biological early warning system

Tubificidae are aquatic annelids which occur abundantly in organically poll uted waters. The anterior end of their body is buried in the sediment, whil e the posterior end moves in the water. This posterior end is (partly) retr acted in the sediment in the presence of defined concentrations of pollutan ts. The retraction can be followed visually (qualitative) or can be monitor ed by videocamera and quantified by digital image analysis. The latter pres ents the advantage of a continuous recording that is always processed the s ame way. Our preliminary results indicate that digital image analysis is an accurate technique for the quantification of the behavioural response of T ubificidae to pollutants. (C) 1999 Elsevier Science Ltd. till rights reserv ed.