Influence of duration of exposure to the pyrethroid fenvalerate on sublethal responses and recovery of Daphnia magna straus

Abstract

This study compares lethal and sublethal responses of Daphnia magna Straus exposed to fenvalerate continuously (21 d) and as a pulse (24 h). Survival was reduced more severely in the continuous- than in the pulse-exposure regime. Complete mortality occurred at 1 microg/L for continuous exposure and at 3.2 microg/L for pulse exposure. Regarding reproductive endpoints, fenvalerate delayed the age at first reproduction. At the beginning of the reproductive phase (day 10), this delay resulted in a reduction of the neonates per living female at similar concentrations in both exposure regimes (0.3 and 0.1 microg/L for continuous and pulse exposure, respectively). The population growth rate was inhibited in continuous and pulse exposure at 0.3 and 0.6 microg/L, respectively. However, the effects of fenvalerate in the pulse exposure were transient. After 21 d, a recovery to values close to the controls occurred with respect to the total neonates per female and the population growth rate over a broad range of concentrations from 0.1 up to 1 microg/L. In contrast, no substantial recovery occurred in the continuous-exposure regime.

Lethal/sublethal responses of Daphnia magna to acute norfloxacin contamination and changes in phytoplankton-zooplankton interactions induced by this antibiotic

“…The above-mentioned results support our first hypothesis that mortality rate would gradually increase with increasing NOR concentration and exposure time. Moreover, we found that the magnitude of the contamination was a more important determinant for NOR toxicity to D. magna individuals than exposure time (Table 1), similarly to that reported for toxicity of organic pollutants, such as fenvalerate24 and chlorpyrifos25.…”

Degradation and toxicity of mitoxantrone and chlorambucil in water

“…Conversely, chlorambucil TP was not stable in water, and it almost completely degraded at 24 h; consequently, toxicity of this compound did not increase with exposure time and decreased exponentially in aged water. Interestingly, chlorambucil LC 50 at 48 h in Table 2 were similar to that of Table 3 in freshly prepared solutions (aged test water 0 h), but twofold lower than that obtained in aged water just 3 h. This means that short-term pulse exposures (\3 h) of chlorambucil were long enough to impair survival in D. magna at 48 h. A similar behaviour was reported for pyrethroid insecticides that showed delayed acute and chronic toxicity to aquatic invertebrate species after short pulses of just a few hours (Medina et al 2004a, b;Reynaldi and Liess 2005;Schulz and Liess 2000).…”

“…Nevertheless, in many cases, it is difficult to associate exposure doses with toxicity, for example when considering pulse exposures (Ashauer et al 2007). There is also the case of xenobiotics having delayed toxicity, which means that they impair organisms live processes long after pulse exposures (Reynaldi and Liess 2005;Schulz and Liess 2000). Finally, many xenobiotics degrade fast in the environment, but their transformation products (TPs) are equally or even more toxic than the parental compounds (Chambers et al 1989).…”

Pyrethroid Insecticides: Use, Environmental Fate, and Ecotoxicology

“…Exposures of 0.01 µg /L fenvalerate and greater over the daphnid life cycle reduced longevity, total reproductive output, brood size, and brood number (Day, 1989). Continuous (21-day) exposure to 0.3 µg/L fenvalerate was also demonstrated to have a greater adverse impact on D. magna reproductive rate than pulsed exposures to higher concentrations, and prevented the recovery of the exposed population (Reynaldi & Liess, 2005). Sublethal pulsed exposure to esfenvalerate negatively affected both the fecundity and mating behavior of Gammarus pulex amphipods.…”