title: Effects of lead-spiked sediments on freshwater bivalve, Hyridella australis: linking organism metal exposure-dose-response.
abstract: Lead entering aquatic ecosystems adsorbs to sediments and has the potential to cause adverse effects on the health of benthic organisms. To evaluate the freshwater bivalve Hyridella australis as a bioindicator for sediment toxicity, their exposure-dose and response to lead contaminated sediments (< 0.01, 205 ± 9 and 419 ± 16 μg/g dry mass) was investigated in laboratory microcosms using 28 day exposures. Despite high concentrations of lead in the sediments, organisms accumulated low concentrations of lead in their tissues after 28 days of exposure (low treatment: 2.2 ± 0.2 μg/g dry mass, high treatment: 4.2 ± 0.1 μg/g dry mass), however, accumulated lead concentrations in lead exposed organisms were two fold (low treatment) and four fold (high treatment) higher than that of unexposed organisms (1.2 ± 0.3 μg/g dry mass). Accumulation of lead by H. australis may have occurred as analogues of calcium and magnesium. Labial palps accumulated significantly more lead than other tissues. Of the lead accumulated in the hepatopancreas, 83%-91% was detoxified and stored in metal rich granules. The proportions and concentrations of lead in this fraction increased with lead exposure, which suggests that lead detoxification pathway plays an important role in metal tolerance of H. australis. The biologically active lead was mainly present in the mitochondrial fraction which increased with lead exposure. Total antioxidant capacity of H. australis significantly decreased while lipid peroxidation and lysosomal membrane destabilation increased with lead exposure. This study showed a clear lead exposure-dose-response relationship and indicates that H. australis would be a good biomonitor for lead in freshwater ecosystems.
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia. Electronic address: chamani.marasinghe.wadige@canberra.edu.au.
authors.forename: Chamani P M
authors.initials: CP
authors.lastname: Marasinghe Wadige
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Taylor
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: William A
authors.initials: WA
authors.lastname: Maher
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: Rodney P
authors.initials: RP
authors.lastname: Ubrihien
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: Frank
authors.initials: F
authors.lastname: Krikowa
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000187:drug effects*; D002118:Calcium / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D005618:Fresh Water; D019015:Geologic Sediments / Q000737:chemistry*; D007854:Lead / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D008274:Magnesium / Q000032:analysis; D012044:Regression Analysis; D012989:Soil Pollutants / Q000633:toxicity*; D014018:Tissue Distribution
chemical_list: D012989:Soil Pollutants; D007854:Lead; D008274:Magnesium; D002118:Calcium
keywords: Biologically active lead; Biologically detoxified lead; Biomarkers; Hyridella australis; Oxidative stress; Sub-cellular partitioning