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

Abstract

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 x 10(5) and 1 x 10(6) 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-LC(50) determination. LC(50) for D. similis was 5.15 x 10(-7) mol l(-1) dissolved Cd without algal cells, whereas with 1 x 10(5) cells ml(-1), it was significantly higher (7.15 x 10(-7) mol l(-1) dissolved Cd). For Cr, the 48 h-LC(50) value of 9.17 x 10(-7) mol l(-1) obtained for the cladoceran in tests with 1 x 10(6) cells ml(-1) of P. subcapitata was also significantly higher than that obtained in tests without algal cells (5.28 x 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.

Different iron sources to study the physiology and biochemistry of iron metabolism in marine micro-algae

“…A strong, non-reversible binding of ferrous iron to the surface of E. huxleyi cells has been previously observed (Sutak et al 2012). Other authors also observed strong iron-binding components in this species (Rodgher et al 2010) or organic iron-binding components excreted by this species (Boye and van den Berg 2000). The strong iron-binding properties of E. huxleyi cells could be part of a strategy used by this organism to take up iron with huge efficiency.…”

Salinization alters ecosystem structure in urban stormwater detention ponds

“…Several recent studies indicate that various zooplankton species are susceptible to nitrite and ammonia (Xiang et al 2010), trace metals such as cadmium and copper (Rodgher et al 2010;Valois et al 2010), and insecticides (Mano et al 2010) among many other pollutants common to stormwater ponds. Nonetheless, high specific conductance levels in stormwater ponds, as measured in our survey, could have prevented the successful colonization and establishment of nearly all zooplankton taxa through the early summer months.…”

Effects of Pollution on Freshwater Organisms

“…Teplova et al New Indicator Organisms. The following new indicator organisms were investigated and proposed for use in aquatic toxicity testing: Daphnia similis (Rodgher et al, 2010), the mayfly Isonychia bicolor (Echols et al, 2010), the freshwater copepod Notodiaptomus conifer (Gutierrez et al, 2010), and the parasite Chordodes nobilii (Achiorno et al, 2010).…”