Effects of test design and temperature in a partial life‐cycle study with the freshwater gastropod <i>Potamopyrgus antipodarum</i>

One of the main objectives of ecological risk assessment is to evaluate the effects of toxicants on ecologically relevant biological systems such as populations or communities. However, the effects of toxicants are commonly measured on selected subindividual or individual endpoints due to their specificity against chemical stressors. Introducing these effects into population models is a promising way to predict impacts on populations. The models currently employed are very simplistic, and their environmental relevance needs to be improved to establish the ecological relevance of hazard assessment. The present study with the gastropod Potamopyrgus antipodarum combines a field experimental approach with a modeling framework. It clarifies the role played by seasonal variability of life-history traits in the population's vulnerability to the alteration of individual performance, potentially due to toxic stress. The present study comprised 3 steps: 1) characterization of the seasonal variability in life-history traits of a local population over 1 yr by using in situ experiments on caged snails, coupled with a demographic follow-up; 2) development of a periodic matrix population model that visualizes the monthly variability of population dynamics; and 3) simulation of the demographic consequences of an alteration in life-history traits (i.e., fertility, juvenile, and adult survival). The results revealed that demographic impacts strongly depend on the season when alterations of individual performance occur. Model analysis showed that this seasonal variability in population vulnerability is strongly related to the phenology of the population. The authors emphasize that improving the realism of population models is a major objective for ecological risk assessment, and that taking into account species phenology in modeling approaches should be a priority.

Section: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Life‐history phenology strongly influences population vulnerability to toxicants: A case study with the mudsnail Potamopyrgus antipodarum

Coulaud

Mouthon²,

Quéau³

et al. 2013

“…In general, estimates of reproduction for P. antipodarum vary widely among studies, and the high variation may be related to differences in experimental design (e.g., light:dark cycle, food quality, etc.). For instance, reproduction in P. antipodarum has been found to be strongly correlated with temperature, with increased reproduction at 16 °C compared with that at 7 °C and 8 °C and compared with that at 24 °C and 25 °C , and furthermore at 20 °C compared with that at 16 °C and 25 °C . In addition, it has been shown that the reproductive cycle of P. antipodarum changes with seasons, both in the field and in the laboratory .…”

Section: Discussionmentioning

confidence: 99%

Bioaccumulation and effects of different‐shaped copper oxide nanoparticles in the deposit‐feeding snail Potamopyrgus antipodarum

Ramskov

Selck

Banta

et al. 2014

Copper oxide (CuO) nanoparticles (NPs) are among the most widely used engineered NPs and are thus likely to end up in the environment, predominantly in sediments. Copper oxide NPs have been found to be toxic to a variety of (mainly pelagic) organisms, but to differing degrees. In the present study, the influence of CuO NP shape on bioavailability and toxicity in the sediment-dwelling freshwater gastropod Potamopyrgus antipodarum was examined. In 2 separate studies, snails were exposed to either clean sediment or sediment spiked with either aqueous Cu or CuO NPs of different shapes (rods, spheres, or platelets) at 240 µg Cu/g dry weight of sediment (nominal). In neither of the studies was survival found to be related to Cu form (i.e., free ion vs particle) or shape, whereas snail growth was severely influenced by both form and shape. Reproduction was affected (by CuO NP spheres and aqueous Cu) only when estimated as the total number (live plus dead) of juveniles produced per snail per week. Both the aqueous and particulate forms of Cu were available for uptake by snails when mixed into sediment. However, Cu body burden was not directly related to observed effects. The present study stresses the need for both a better understanding of uptake mechanisms and internal distribution pathways of NPs and an assessment of long-term consequences of NP exposure.

“…Moreover, the present study emphasizes the importance of appropriate test durations, especially for the investigation of sublethal effects. Although Macken et al , for example, demonstrated that significant differences in the reproduction can occur after 28 d, the impact of SOT would not have been observed within this time period. Therefore, our results support the recommended test duration of 8 wk for the establishment of a standard chronic ecotoxicological test with the New Zealand mudsnail P. antipodarum .…”

Section: Discussionmentioning

confidence: 91%

Sublethal effects of the beta‐blocker sotalol at environmentally relevant concentrations on the New Zealand mudsnail Potamopyrgus antipodarum

Feiner

Laforsch

Letzel

et al. 2014

Monitoring sublethal effects of pharmaceuticals on nontarget species in aquatic environments has become an important topic in ecotoxicology, yet few studies have been conducted concerning the effects of beta-blockers on aquatic organisms. The present study investigated the effects of the beta-blocker sotalol (SOT) at 3 environmentally relevant concentrations on life-history traits of the New Zealand mudsnail Potamopyrgus antipodarum. Based on the pharmacodynamic properties of SOT, the authors hypothesized reduced numbers of embryos in the brood pouches, decelerated growth of adult snails, and smaller size of neonates, but no effect on mortality rates of adults. Contrary to the hypothesis, the total number of embryos was significantly higher after 56 d of exposure at nominal concentrations of 0.05 µg/L and 1.0 µg/L by 107% and 73%, respectively. No differences in embryo numbers were observed at earlier time-points. Therefore, the mode of action seems to be an extension of the reproductive period rather than an increase of the embryo production. Furthermore, our results indicate a hormetic dose-response relationship, because no effects were observed at the highest test-concentration (6.5 µg/L). Mortality, growth of adult snails, and neonate sizes were not affected by the beta-blocker. Given the strong influence on reproduction, the effects of sublethal concentrations of SOT and other beta-blockers deserve better consideration in ecotoxicological risk assessment.