title: Effects of cadmium and zinc toxicity on orientation behaviour of Echinoparyphium recurvatum (Digenea: Echinostomatidae) cercariae.
abstract: The effects of cadmium and zinc toxicity on orientation behaviour (photo- and geo-taxis) of Echinoparyphium recurvatum cercariae was investigated at concentrations ranging from 10 to 1000 microg l(-1). Exposure to the toxicants at all metal concentrations caused a change in orientation to negative phototaxis and positive geotaxis during the submaximal dispersal phase (0.5 h cercarial age). Autometallography staining of cercariae exposed to 1000 microg l(-1) cadmium or zinc showed selective binding of heavy metals to tegumental surface sites associated with sensory receptors. The significance to parasite transmission of changes in cercarial orientation behaviour in metal polluted environments is discussed.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom. n.morley@rhul.ac.uk
authors.forename: N J
authors.initials: NJ
authors.lastname: Morley
authors.forename: M
authors.initials: M
authors.lastname: Crane
authors.forename: J W
authors.initials: JW
authors.lastname: Lewis
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D004450:Echinostomatidae / Q000033:anatomy & histology / Q000502:physiology*; D006652:Histological Techniques; D009949:Orientation / Q000187:drug effects*; D016622:Silver Staining; D015032:Zinc / Q000633:toxicity*
chemical_list: D002104:Cadmium; D015032:Zinc