How does growth temperature affect cadmium toxicity measured on different life history traits in the soil nematode Caenorhabditis elegans?

Abstract

Environmental factors, in particular temperature, have been shown to affect the toxicity of chemicals. In the present study the authors exposed the nematode Caenorhabditis elegans to five concentrations of Cd (2, 4, 6, 8, and 10 mg Cd/L agar) at four constant temperatures (11, 15, 18, and 21°C) and monitored survival and reproduction on a daily basis. Data were incorporated in a population matrix model to determine the population growth rate (PGR). An additional experiment at 15 and 20°C and 0, 1, 5, and 10 mg Cd/L was performed to include growth measurements in order to relate changes in reproduction to resource allocations between investments in growth and reproduction. The impacts of Cd on PGR increased with increasing temperature, shifting the median effective concentration (EC50) for PGR from 11.6 ± 5.4 and 9.2 ± 1.3 at 11°C and 15°C, to 2.1 ± 0.1 and 1.7 ± 0.4 at 18°C and 21°C. Cadmium and temperature decreased growth rates, but Cd also increased maturation times and decreased final body size. It is hypothesized that Cd toxicity leads to a decrease in nutrient assimilation and that this "chemical anorexia" is more severe at high temperatures, where energy demands for growth and reproduction are the highest.

Low temperatures enhance the toxicity of copper and cadmium toEnchytraeus crypticusthrough different mechanisms

“…The present study presents a unique case of increased metal toxicity with decreasing temperature, when assessed in a reproductive assay. To our knowledge, all previous studies on metal toxicity and temperature have shown either the opposite trend of increasing toxicity with increasing temperature or no temperature effect . Most of these studies have assessed toxicity at identical exposure times rather than at similar physiological times, as was done in the present study, which could have affected the results.…”

“…Other studies on the toxicity of Cd using either population growth rate of nematodes as an endpoint or toxicity after the production of 3 clutches of Daphnia magna , however, still showed higher toxicities at high temperatures, similar to studies using identical exposure times. Only the magnitude of the temperature sensitivity of the toxic response varied between the acute identical time studies and chronic studies assessing toxicities at similar physiological states, as discussed by Nørgaard et al . We therefore believe that the decreased toxicity with increasing temperature observed in the enchytraeids in the present study is related to the temperature affecting the balance of uptake and excretion/immobilization processes of the metals or the balance between damage and repair rates differently from how temperature is affecting these balances in nematodes and daphnia.…”

“…This is the pattern most often observed for tissue Cd concentrations as a function of time , although some species have been shown to be able either to not take up Cd or to excrete Cd . Studies in other species have shown Cd uptake to increase with increasing temperature , but they also found that toxicity measured on reproductive output increased with increasing temperature in the species Daphnia magna and Caenorhabditis elegans . We found the opposite to be the case for E. crypticus (Figure B).…”

“…Following the conclusions of Heugens et al's meta‐analysis, we hypothesized that increasing temperature will result in greater toxicity. In addition, results were confirmed by a lifecycle study with the nematode Caenorhabditis elegans and Cd in temperatures ranging from 11 °C to 21 °C . The patterns of change in the sensitivity of the test species to the 2 metals were interpreted in relation to potential mechanisms through which temperature could influence the species sensitivity against metal exposure.…”

Diplolaimella dievengatensis (Nematoda: Monhysteridae) as model organism in ecotoxicity assay

“…Such costs may decrease the energy available for other functional outputs like growth and reproduction, which can ultimately lead to reduced population growth and survival (Calow & Sibly, 1990). For this reason, quantification of individual life-cycle traits has become a useful tool to assess the risk of anthropogenic pollutants on ecosystems (Kammenga et al, 1996;Nørhave et al, 2012;Jager et al, 2014). Individual growth, reproduction and survival have been the most commonly used parameters (Hansen et al, 1999;Roh et al, 2007).…”