title: Uranium bioaccumulation in a freshwater ecosystem: impact of feeding ecology.
abstract: The objectives of our study were: (1) to determine if there was significant uranium (U) bioaccumulation in a lake that had been historically affected by a U mine and (2) to use a combined approach of gut content examination and stable nitrogen and carbon isotope analysis to determine if U bioaccumulation in fish was linked to foodweb ecology. We collected three species of fish: smallmouth bass (Micropterus dolomieu), yellow perch (Perca flavescens) and bluegill (Lepomis macrochirus), in addition to several invertebrate species including freshwater bivalves (family: Sphaeriidae), dragonfly nymphs (order: Odonata), snails (class: Gastropoda) and zooplankton (family: Daphniidae). Results showed significant U bioaccumulation in the lake impacted by historical mining activities. Uranium accumulation was 2-3 orders of magnitude higher in invertebrates than in the fish species. Within fish, U was measured in operculum (bone), liver and muscle tissue and accumulation followed the order: operculum>liver>muscle. There was a negative relationship between stable nitrogen ratios ((15)N/(14)N) and U bioaccumulation, suggesting U biodilution in the foodweb. Uranium bioaccumulation in all three tissues (bone, liver, muscle) varied among fish species in a consistent manner and followed the order: bluegill>yellow perch>smallmouth bass. Collectively, gut content and stable isotope analysis suggests that invertebrate-consuming fish species (i.e. bluegill) have the highest U levels, while fish species that were mainly piscivores (i.e. smallmouth bass) have the lowest U levels. Our study highlights the importance of understanding the feeding ecology of fish when trying to predict U accumulation.
authors.affiliation: Trent University, Peterborough, ON, Canada. lisakraemer@trentu.ca
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Kraemer
authors.forename: Douglas
authors.initials: D
authors.lastname: Evans
mesh_terms: D000818:Animals; D020387:Food Chain; D005766:Gastrointestinal Contents; D007448:Invertebrates / Q000737:chemistry; D060106:Lakes / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000032:analysis; D010473:Perciformes / Q000502:physiology*; D014018:Tissue Distribution; D014501:Uranium / Q000032:analysis / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical; D014501:Uranium