The invasive New Zealand mudsnail Potamopyrgus antipodarum is now well established in rivers in the western United States and is rapidly expanding its range. Potamopyrgus antipodarum is most likely to be spread to new waters via contaminated equipment. To assess a possible method for controlling their spread, we conducted a desiccation and freezing experiment on seven size-classes of P. antipodarum to determine mortality at different temperatures and low or high humidity. Our results show that P. antipodarum does not survive freezing or desiccation at high temperatures with low humidity. At all temperatures, larger P. antipodarum generally survived desiccation longer than smaller ones, and for all size-classes mortality generally increased with increased exposure time. We recommend thoroughly freezing or drying potentially contaminated equipment to limit the spread of P. antipodarum to uninfected aquatic ecosystems.
The essential oil of Tetradenia riparia had limited acute toxicity to adult Zabrotes subfasciatus, with females, which are larger, being less susceptible than males. However, freshly‐applied essential oil at a predicted concentration of 250 μg/cm2 of pinto bean surface completely suppressed the production of F1 adult progeny, with an EC50 of 72 μg/cm2. Eggs were sensitive to this preparation with an EC50 of 50 μg/cm2 of bean surface for F1 adult progeny per parental female. This concentration‐dependant effect upon the eggs was greatly enhanced by physical damage to the eggs during the treatment process, resulting in a population size 21 % of that achieved in controls. Larvae within the beans were well protected from the oil treatment with an EC50 of approximately 3980 μg/cm2 for F1 adult progeny per parental female. However, the EC50 for numbers of subsequent adult F2 progeny for these emergent F1 adults was 121 μg/cm2 of pinto bean surface. This value was similar to that for the freshly‐applied oil against adults, but the data followed a distinctly different distribution that was characterized by limited adult emergence during days 55–85. Emergence occurred even at extremely high concentrations, whereas no adults could emerge (because either no eggs were laid or none survived) for these concentrations when the treatment was directed at either the parental adults or eggs. The activity of the oil increased at 210 days post‐application with an EC50 of 23 μg/cm2 of pinto bean surface for hatched eggs per parental female at 25 days post‐inoculation. The essential oil is quite repellant to ovipositing females after this period of incubation with an EC50 of only 10 μg/cm2 of pinto bean surface. Volatiles emitted after this duration of incubation had a weak but significant effect on fecundity of females selecting untreated beans in a choice test. The essential oil had no effect on bean germination at 180 days. The logistic dose‐response transition equation, y = a + {b/[1 +(x/c)d]}, may better fit resulting population size estimates for experiments involving a ‘dose‐response’ than probit analysis, because midpoints can be determined for transitions in which partial suppression data are limited. We conclude that the essential oil of T. riparia may make an effective seed treatment against Z. subfasciatus at 1.7 1/to; but to be used as a treatment for beans for consumption, additional research must evaluate mammalian toxicity and palatability of these treated beans.
The results from our investigation suggest that adhering to an ERAS protocol confers beneficial hospital length of stay and hospital cost outcomes, without compromising patient readmission rates. Additional investigation scrutinizing the impact of ERAS enactment with more defined study variables in a larger, randomized setting is warranted.
Water levels in the regulated Snake River, southern Idaho, U.S.A. can fluctuate daily and seasonally due to hydroelectric demands. The federally listed threatened Bliss Rapids snail, Taylorconclia serpenticola Hershler et al., 1994 (Family: Hydrobiidae), survives in and near these fluctuation zones. Remaining T. serpenticola populations occur only in sections of the Snake River that are impacted by these hydroelectric facilities and associated springs. Because effects of rapid draw-down in fluctuation zones on T. serpenticola are unknown, we conducted a laboratory experiment to evaluate potential impacts of desiccation. Our experiment compared desiccation resistance at several air temperatures, on dry and wetted substrates, and for ‘small’ vs. ‘large’ snails. Probit regression-maximum likelihood models estimated lethal time (LTj,,) values. Suiwival was significantly greater on wetted substrate than on dry substrate and was lowest at temperatures <0‘’C and at 37'^C on dry substrate. Survival was greatest at 17°C on wetted substrate. There was no significant difference in survival at temperatures above 0°C on dry substrate other than at 37°C. LTj,, survival ranged from 0.5 hours at -7°C to 157.0 hours at 17°C on wetted substrate. There were no significant differences in survival relative to snail size in any treatment. Our results suggest that desiccation could impact T. serpenticola populations if snails become stranded on dry substrates during rapid water-level fluctuations of the Snake River, particularly during subzero winter or extreme high summer temperatures. The most important factor determining survival would be the ability to find refuge on the undersides of cobbles, where snails typically occur, or in habitats that remained moist for the duration ot the draw-down of the river.
Water temperatures are warming throughout the world including the Pacific Northwest, USA. Benthic macroinvertebrates are one of the most important and widely used indicators of freshwater impairment; however, their response to increased water temperatures and their use for monitoring water temperature impairment has been hindered by lack of knowledge of temperature occurrences, threshold change points, or indicator taxa. We present new analysis of a large macroinvertebrate database provided by Idaho Department of Environmental Quality from wadeable streams in Idaho that is to be used in conjunction with our previous analyses. This new analysis provides threshold change points for over 400 taxa along an increasing temperature gradient and provides a list of statistically important indicator taxa. The macroinvertebrate assemblage temperature change point for the taxa that decreased with increased temperatures was determined to be about 20.5 °C and for the taxa assemblage that increased with increased temperatures was about 11.5 °C. Results of this new analysis combined with our previous analysis will also be useful for others in neighboring regions where these taxa occur.
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