title: Toxicity of cadmium and zinc to Diplostomum spathaceum (Trematoda: Diplostomidae) cercarial survival.
abstract: The toxicity of cadmium and zinc at concentrations ranging from 0.1 to 10000 microg/l was investigated with cercariae of Diplostomum spathaceum at three temperatures (12, 20, 25 degrees C) and three levels of water hardness (distilled water, soft water, hard water). Under most environmental conditions survival of cercariae was reduced by increasing metal concentration. Increasing water hardness and decreasing water temperature caused an increase in the survival of both control and metal exposed cercariae. However, with decreasing temperature increased survival of metal-exposed cercariae above the control occurred at a number of low metal concentrations. Differences in the relative toxicity of cadmium and zinc to cercariae was dependent on the environmental conditions of exposure. The two heavy metals demonstrated little toxicity to cercariae during the period of maximum cercarial infectivity (0-5 h). The mechanisms of metal toxicity and their effects on cercarial survival are discussed.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 OEX, UK. 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*; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008195:Lymnaea / Q000469:parasitology; D016019:Survival Analysis; D013696:Temperature; D013997:Time Factors; D014200:Trematoda / Q000187:drug effects* / Q000254:growth & development; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015032:Zinc / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D015032:Zinc