Kinetic uptake of bioavailable cadmium, selenium, and zinc by Daphnia magna

Abstract

Kinetic uptake of Cd, Se(IV), and Zn by Daphnia magna from the dissolved phase was determined using radiotracer techniques in moderately hard water. The metal influx rate and distribution in the soft tissue and the exoskeleton of the daphnids as influenced by metal concentration, inorganic ligands including pH, Ca2+ and SO4(2-), and body size were quantified. When the metal concentrations were <180 nM for Cd and <769 nM for Zn, the concentration factor in daphnids increased linearly within the 12 h of exposure. At a higher concentration, apparent steady state was reached after 3 h of exposure. Cadmium and Zn distribution in the soft tissues was not affected by the total ambient concentrations, whereas Se distribution in the soft tissue decreased by 7 to 10% with increasing Se concentration from 16 to 643 nM. A linear positive power relationship was found between the influx rates of the metals and the ambient concentrations. The concentration factor for Se, however, decreased significantly with increasing Se concentration in water. The influx rate of metals was inversely related to the body size in a power function. When the pH in ambient water increased from 5.0 to 7.0, the influx rate of Cd, Se, and Zn increased by 2.9, 16.6, and 4.1 times, respectively. The influx rates of Cd, Se, and Zn decreased by 6.9, 8.7, and 4.4 times, respectively, with an increase in Ca2+ concentration from 0.6 to 5.1 mM. In contrast, the uptake rates of all three metals were not significantly affected by the SO4(2-) concentration. The majority of accumulated Se was distributed in the soft tissues after 12 h of exposure, whereas Cd and Zn were about evenly distributed in the soft tissue and exoskeleton. Any changes in pH, Ca2+, and SO4(2-) concentrations did not apparently affect their distributions in the daphnids. Our study provides important kinetic data necessary for delineating the exposure routes and for further development of the biotic ligand model in Daphnia. Using a bioenergetic-based kinetic model, we showed that the dissolved uptake is dominant for Zn accumulation (>50%). For Cd and Se, dietary exposure is dominant when the bioconcentration factors of these metals in phytoplankton are at the high end.

Influence of Algae Age and Population on the Response to TiO2 Nanoparticles

“…The increased sensitivity was attributed to larger area/volume ratios, which led to a size-dependent uptake and higher metabolic rates of younger organisms. Similar findings were observed by Yu and Wang [ 57 ], Hutchinson et al [ 58 ], and Stuhlbacher et al [ 59 ]. The response to a stressor can be affected by an organism’s physiological state.…”

Persisting Effects in Daphnia magna Following an Acute Exposure to Flowback and Produced Waters from the Montney Formation

“…A slight decrease in molts was observed with higher FPW concentrations; however, this trend was not significant (Figure B; p = 0.250). Overall, these results are similar to previous work in Daphnia exposed to FPW for 21 days. , Neonate Daphnia are more sensitive than their adult counterparts, due to their high mass-specific metabolic rate and higher surface area to volume ratio, increasing the potential contact points for transport across the epithelium . Previous studies showed that neonate Daphnia had lower survival, neonate production, and first brood size to metal stressors than 7 days adult Daphnia , and that LC50s for FPW were vastly lower in neonates (0.19%) than in adults (7 days old) Daphnia (0.75%) .…”

“…22,32 Neonate Daphnia are more sensitive than their adult counterparts, due to their high mass-specific metabolic rate and higher surface area to volume ratio, increasing the potential contact points for transport across the epithelium. 71 Previous studies showed that neonate Daphnia had lower survival, neonate production, and first brood size to metal stressors than 7 days adult Daphnia, 72 and that LC50s for FPW were vastly lower in neonates (0.19%) than in adults (7 days old) Daphnia (0.75%). 32 The observed changes to reproduction are unsurprising considering the high mortality observed in each FPW sample.…”

Differential accumulation of metals in the lacustrine and fluvial Alpine bullheads (Cottus poecilopus) and recovery of fish from metal contamination after a flash flood

“…Liver is probably the main receptor of zinc in summer, when the amount of ingested metals from diet originates mainly from larvae of midges (Pastorino et al 2020c ). Chironomidae have high concentrations of zinc probably because of their inefficient efflux rates or detoxification mechanisms, as reported in some other studies on aquatic invertebrates (Yu and Wang 2002 ). Compared to other fish species, bullheads seem to prefer water with relatively higher zinc content (Andreji and Dvorak 2018 ).…”