title: Distribution of haemic neoplasia of soft-shelled clams in Prince Edward Island: an examination of anthropogenic factors and effects of experimental fungicide exposure.
abstract: Haemic neoplasia was first considered a disease of concern for soft-shell clams in Prince Edward Island (PEI) when it was diagnosed as the cause of mass mortalities in 1999. The aetiology of the disease remains elusive, but has been associated with environmental degradation. In this study, a 2-year (2001-2002) geographic and seasonal survey was conducted for haemic neoplasia, using histology, in soft-shell clams from PEI. In addition, using geographic information system, the association between anthropogenic factors in the watersheds at sites affected by haemic neoplasia and the prevalence of the disease was investigated. Finally, histopathological changes were assessed in soft-shell clams experimentally exposed to four concentrations of chlorothalonil for 27 days. Haemic neoplasia could not be induced at any concentration of chlorothalonil. Clams exposed to a concentration of 1000 μg L(-1) of the fungicide, however, exhibited an LC50 of 17 days. Although this information provides additional toxicity information (LC50) for soft-shell clams, further experiments are required to assess longer term exposure to the fungicide. The highest prevalences of haemic neoplasia in PEI were found in North River and Miscouche (28.3-50.9% and 33.0-77.8%, respectively). No clear seasonal patterns were found. There was a correlation between haemic neoplasia prevalence and watersheds with a high percentage of potato acreage and forest coverage (P = 0.026 and P = 0.045, respectively), suggesting a link between anthropogenic activity and the prevalence of the disease.
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: D R
authors.initials: DR
authors.lastname: Mateo
authors.affiliation: Gulf Biocontainment Unit, Fisheries and Oceans Canada, Charlottetown, PE, Canada.
authors.forename: G S
authors.initials: GS
authors.lastname: MacCallum
authors.affiliation: St. Andrews Biological Station, Fisheries and Oceans Canada, St. Andrews, NB, Canada.
authors.forename: S E
authors.initials: SE
authors.lastname: McGladdery
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Davidson
mesh_terms: D000818:Animals; D006434:Hemocytes / Q000187:drug effects / Q000473:pathology; D007928:Lethal Dose 50; D049892:Mya / Q000166:cytology / Q000187:drug effects*; D009570:Nitriles / Q000633:toxicity*; D011325:Prince Edward Island; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D009570:Nitriles; D014874:Water Pollutants, Chemical; C005806:tetrachloroisophthalonitrile
keywords: Haemic neoplasia; Mya arenaria; anthropogenic; chlorothalonil; histopathology