Differences in acute toxicity test results of three reference toxicants on Daphnia at two temperatures

Abstract

Ten 48‐h static acute toxicity tests were conducted with Daphnia magna Straus and Daphnia pulex Leydig with each of the three reference toxicants — sodium dodecyl sulfate (SDS), sodium pentachlorophenate (NaPCP), and cadmium (Cd) (as CdCl2) — at 20 and 26°C to investigate the effect of temperature on test results at the temperature extremes usually encountered during field studies. The mean 48‐h LC50 value for SDS with Daphnia pulex at 26°C was lower (10.2 mg/L) than at 20°C (12.6 mg/L), but the difference was not significant (α = 0.05). For Daphnia magna the mean LC50 was significantly (α = 0.05) lower at 26°C (10.8 mg/L) than at 20°C (13.5 mg/L). Sensitivity of either species to NaPCP was not significantly different (α = 0.05) at the two temperatures. The data show a fourfold increase in sensitivity to Cd at the higher temperature with Daphnia magna (mean LC50 = 0.038 mg/L at 20°C and 0.009 mg/L at 26°C) and a sevenfold increase with Daphnia pulex (mean LC50 = 0.042 mg/L at 20°C and 0.006 mg/L at 26°C). These data indicate that toxicity tests conducted at 20 and 26°C may give significantly different results with Daphnia. Because test precision, control survival, and the likelihood of obtaining valid tests are better at 20°C, that temperature is recommended for acute toxicity tests with Daphnia.

Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein

“…Daphnia pulex arenata is a member of the Daphnia pulex complex, and this isolate is from the same population as the strain whose genome was sequenced and assembled into a reference Daphnia were housed in 4 L borosilicate glass beakers (40 per beaker) held inside an environmental chamber at a constant temperature (19 ± 1 °C) and photoperiod (16:8 light-dark) . Organisms were maintained in nanopure water reconstituted to moderate hardness (89 ± 16 mg CaCO3/L), renewed weekly, and fed Ankistrodesmus falcatus three times per week at a rate of 75000 cells/mL.…”

Ecotoxicity of plant extracts and essential oils: A review

“…The ethanolic extract resulted in a 24 h LC 50 of 0.093 mg.L − 1 and the hexane extract of 0.103 mg.L − 1 , besides these extracts, a hydrolate presented a 24 h LC 50 of 0.236% (Pino-Otín et al, 2019a). The difference between these studies relies on the Daphnia species used, one used D. pulex and the other D. magna, but the differences in toxicity observed should not be down to this fact as similarities in toxicities of many toxicants have been reported between the two species (Lewis and Horning II, 1991;Lilius et al, 1995) and both are suitable for acute toxicity tests according to the OECD guideline (OECD, 2004). The difference could be due to environmental factors that can affect the production of secondary metabolites and, particularly concerning the differences in the hydrolate, it is noticeable that one of the studies reports EC 50 values and the other LC 50 , which usually mean the measurement of different parameters (e.g., immobilisation vs lethality), and the units used are also different (mg.L − 1 and percentage of dilution).…”

Identifying Toxic Impacts of Metals Potentially Released during Deep-Sea Mining—A Synthesis of the Challenges to Quantifying Risk

“…Whilst these observations of temperature-mediated toxicity are not new (e.g., Lewis and Horning, 1991;Heugens et al, 2003;Khan et al, 2006;Prato et al, 2008;Barbieri et al, 2013), to the extent that authors have suggested the use of a correction factor in applying LC 50 values for different temperature environments (Wang et al, 2014), the moderating effects of temperature may not be consistent within the real world (see Chapman et al, 2006). Moreover data indicate that the determination of any "temperature correction factor" will be different at high hydrostatic pressure for each metal in question and would have to be empirically determined for each case, and potentially for each biological species (see also: Kiffney and Clements, 1996;Gonzalez-Rey et al, 2007;Wang et al, 2014;for example).…”