title: Impact of municipal effluents and hydrological regime on myxozoan parasite communities of fish.
abstract: Increased productivity from sewage effluents can enhance species richness locally. Results from a study of spottail shiners (Notropis hudsonius) in 1999 showed that prevalence and the mean number of myxozoan parasite species per host were higher downstream of the wastewater outflow from the Island of Montreal than upstream in the St. Lawrence River, Quebec, Canada. This was attributed to organic enrichment of the sediments which presumably lead to increased densities of oligochaetes, the alternate hosts, downstream of Montreal. Spottail shiners subsequently were collected every August/early September in 2001-2004 to examine the stability and repeatability of these patterns. Prevalence and mean number of myxozoan species per fish typically were again higher downstream of the sewage source each year compared to upstream, although there was no significant difference in these measurements pooled across years between localities immediately upstream and downstream of the effluent outflow. Density of the oligochaete Limnodrilus hoffmeistereri, a common alternate host of myxozoans, was much higher at two downstream localities than at an upstream one. At a larger spatial scale, mean myxozoan infracommunity richness across sites in the St. Lawrence River was negatively correlated with mean water levels measured in the 3 months prior to fish sampling. Results suggest that on a local scale, variations in prevalence and diversity among localities are influenced by municipal effluents, but that at a landscape scale annual variations across sites are affected by the hydrological regime and climate. In effect, water level fluctuation had a landscape-wide impact that was superimposed over pollution-induced local variations.
authors.affiliation: Fluvial Ecosystem Research Section, Aquatic Ecosystem Protection Research Division, Water Science and Technology Directorate, Science and Technology Branch, Environment Canada, St. Lawrence Centre, 105 McGill, 7th Floor, Montreal, Que., Canada H2Y 2E7. david.marcogliese@ec.gc.ca
authors.forename: David J
authors.initials: DJ
authors.lastname: Marcogliese
authors.forename: Andrée D
authors.initials: AD
authors.lastname: Gendron
authors.forename: David K
authors.initials: DK
authors.lastname: Cone
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D005393:Fish Diseases / Q000469:parasitology*; D005399:Fishes / Q000469:parasitology*; D005618:Fresh Water / Q000032:analysis; D006790:Host-Parasite Interactions; D055764:Myxozoa / Q000145:classification / Q000302:isolation & purification* / Q000502:physiology; D011792:Quebec; D012722:Sewage / Q000032:analysis; D013997:Time Factors; D014876:Water Pollution / Q000032:analysis
chemical_list: D012722:Sewage