Effects of chronic dietary and waterborne cadmium exposures on the contamination level and reproduction of daphnia magna

Abstract

Regulatory assessments of metal toxicity on freshwater organisms assume that toxic effects are caused by dissolved metals. In aquatic systems, organisms are exposed to both dissolved and particulate-bound metals. In this study, the chronic toxicity of dietary cadmium (Cd) on the reproduction and Cd body burden of Daphnia magna was investigated. Daphnids (<24 h) were successively exposed to dissolved Cd (8 h) and then to uncontaminated or contaminated algae (16 h) for 21 d. The results show a higher Cd burden in daphnids because of the addition of contaminated food and reveal that Cd uptake by D. magna from water and food was additive for the lowest Cd concentrations tested. Similar Cd distributions (cytosolic and insoluble fractions) were observed in the two groups of organisms, showing similar potential toxicity of Cd accumulated from the two exposure routes. Dietary Cd induces deleterious effects on D. magna reproduction. On the basis of Cd body burden of daphnids, the results support the claim that waterborne and dietary Cd exposures were additive in causing toxicity for Cd concentrations lower than 25 microg/L. At the highest Cd concentrations, the importance of dietary Cd on the daphnid contamination level decreases and confounding factors such as feeding rate reduction seem to appear, which induce an effect on neonate reproduction. In this study, we illustrate the need to take the dietary pathway into account in regulatory assessments and to establish effective concentrations with particulate-bound metals.

Effects of dietborne cadmium on life history and secondary production of a tropical freshwater cladoceran

“…Several studies have demonstrated the importance of dietborne in metal exposure and toxicity to zooplankton. Production of neonates by Daphnia magna was significantly reduced when its diet (Pseudokirchneriella subcapitata) was contaminated with Cd (Geffard et al 2008); toxic effects were observed on the survival and reproductive aspects of Moina monogolica fed on Cd contaminated Chlorella pyrenoidosa (Wang et al 2010). Similar effects on fecundity and survival were reported for other daphnid species like Ceriodaphnia dubia (Rodgher and Espíndola 2008).…”

“…Environmental assessments of metals in freshwater ecosystems presume that toxicity is mainly caused by aqueous exposure (Geffard et al 2008). However, there is evidence that dietborne metals might be an important toxicity pathway for aquatic consumers (De Schamphelaere et al 2007).…”

Cadmium and Chromium Toxicity to Pseudokirchneriella subcapitata and Microcystis aeruginosa

“…The metal accumulated by the cell could be interpreted as the total particulate metal (metal species as quantified in this study). For example, the metal that is transported with the cell to other trophic levels, as demonstrated in literature (Fisher and Hook 2002;Wilding and Maltby 2006;Geffard et al 2008). In addition, M. aeruginosa showed higher sensibility to the metals in comparison to the green algae, showing that the cyanobacterium was more suitable for monitoring the contaminated aquatic bodies with Cd and Cr.…”

Effects of dietary cadmium exposure on reproduction of saltwater cladoceran Moina monogolica Daday: Implications in water quality criteria

“…Wang et al to the values reported by some researchers [18]. However, these values were much lower than those obtained for Skeletonema costatum and Tetraselmis suecia, perhaps because the various algal strains have different exclusion mechanisms and detoxification processes when exposed to cadmium [19], which also produced different cadmium burdens of various algal species [20]. The reproductive toxicity of dietary cadmium on M. monogolica observed in the present study is in agreement with similar studies on C. dubia by Sofyan et al [4] but is markedly different from those on D. magna.…”