title: Acartia tonsa eggs as a biomonitor to evaluate bioavailability/toxicity of persistent contaminants in anoxic/sulfidic conditions: The case of cadmium and nickel.
abstract: The evaluation of toxicity due to persistent pollutants in anoxic aquatic environments has met with various problems, as most test organisms can not withstand oxygen lack and exposure to free sulfide. We evaluated the suitability of the eggs of the brackish copepod Acartia tonsa for bioassays in anoxic/sulfidic conditions: when exposed to deep hypoxia and free sulfide, the eggs become quiescent and are able to resume hatching after restoring normoxic conditions. Tests with cadmium and nickel were performed in normoxic and deeply hypoxic conditions and in anoxic water containing H2S or H2S+FeSO4 on an equimolar basis. Active and quiescent eggs showed equivalent sensitivity to the metals, both suffering significant reductions in hatching success at 89μM Cd and 17μM Ni. As expected on the basis of the SEM/AVS model, Cd toxicity was almost completely suppressed in presence of sulfides. Dissolved Cd concentration drastically dropped and hatching success was generally >80%, as against values <6% observed in sulfide-free water, indicating that the applied experimental procedure can simulate metal-sulfide interaction. Ni toxicity was only slightly reduced by the presence of sulfides. High dissolved Ni concentrations were detected and mean hatching percentages were ≤32%, suggesting that Ni bioavailability/toxicity was only partially controlled by excess reactive sulfides. The results suggest that A. tonsa eggs could be a useful biomonitor to evaluate toxicity due persistent contaminants in anoxic conditions and the role of sulfides in reducing metal bioavailability/toxicity.
authors.affiliation: Department of Life Sciences - University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Sei
authors.affiliation: Department of Life Sciences - University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
authors.forename: Marion
authors.initials: M
authors.lastname: Invidia
authors.affiliation: Department of Chemistry - University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Giannetto
authors.affiliation: Department of Life Sciences - University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy. Electronic address: gessica.gorbi@unipr.it.
authors.forename: Gessica
authors.initials: G
authors.lastname: Gorbi
mesh_terms: D000818:Animals; D001682:Biological Availability; D002104:Cadmium / Q000633:toxicity*; D033342:Copepoda / Q000187:drug effects*; D019015:Geologic Sediments / Q000737:chemistry; D000075322:Heavy Metal Poisoning; D009532:Nickel / Q000633:toxicity*; D010063:Ovum / Q000187:drug effects*; D011041:Poisoning; D013440:Sulfides / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D013440:Sulfides; D014874:Water Pollutants, Chemical; D002104:Cadmium; D009532:Nickel
keywords: Acartia tonsa eggs; Cadmium; Deep hypoxia; Nickel; Quiescence; SEM/AVS model; Sulfides; Toxicity