Suitability of Daphnia similis as an alternative organism in ecotoxicological tests: implications for metal toxicity

• Published in: Ecotoxicology (London) 2010-08, Vol.19 (6), p.1027-1033
• Main Authors: Rodgher, Suzelei, Espíndola, Evaldo Luiz Gaeta, Lombardi, Ana Teresa
• Format: Article
• Language: English
• Subjects: Acute toxicity; Animals; Bioassays; Cadmium; Cadmium - analysis; Cadmium - chemistry; Cadmium - toxicity; Chlorophycota; Chlorophyta - physiology; Chromium; Chromium - analysis; Chromium - chemistry; Chromium - toxicity; Cladding; Cladoceran; Culture; Daphnia - drug effects; Daphnia - metabolism; Dissolution; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental Monitoring - methods; Environmental Pollution - analysis; Ethylenediaminetetraacetic acid; Freshwater; LC; Lethal Dose 50; Metal concentrations; Metals, Heavy - analysis; Metals, Heavy - chemistry; Metals, Heavy - toxicity; Neonates; Organisms; Speciation; Species Specificity; Technical Note; Toxicity; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity; Zooplankton
• ISSN: 0963-9292; 1573-3017
• DOI: 10.1007/s10646-010-0484-1

The acute toxicity of metals to Daphnia similis was determined and compared to other daphnid species to evaluate the suitability of this organism in ecotoxicology bioassays. To verify the performance D. similis in toxicity tests, we also investigated the effect of Pseudokirchneriella subcapitata at 1 × 10⁵ and 1 × 10⁶ cells ml⁻¹ on Cd and Cr acute toxicity to the cladoceran. Daphnid neonates were exposed to a range of chromium and cadmium concentrations in the absence and presence of the algal cells. Metal speciation calculations using MINEQL⁺ showed that total dissolved metal concentrations in zooplankton culture corresponded to 96.2% free Cd and 100% free Cr concentrations. Initial total dissolved metal concentrations were used for 48 h-LC₅₀ determination. LC₅₀ for D. similis was 5.15 × 10⁻⁷ mol l⁻¹ dissolved Cd without algal cells, whereas with 1 × 10⁵ cells ml⁻¹, it was significantly higher (7.15 × 10⁻⁷ mol l⁻¹ dissolved Cd). For Cr, the 48 h-LC₅₀ value of 9.17 × 10⁻⁷ mol l⁻¹ obtained for the cladoceran in tests with 1 × 10⁶ cells ml⁻¹ of P. subcapitata was also significantly higher than that obtained in tests without algal cells (5.28 × 10⁻⁷ mol l⁻¹ dissolved Cr). The presence of algal cells reduced the toxicity of metals to D. similis, as observed in other studies that investigated the effects of food on metal toxicity to standard cladocerans. Comparing our results to those of literature, we observed that D. similis is as sensitive to metals as other standardized Daphnia species and may serve as a potential test species in ecotoxicological evaluations.