for snail care. John Logsdon contributed to snail collections. David ("Davey") Neiman contributed his Excel expertise to data analysis. Several anonymous reviewers of an earlier version of the manuscript provided valuable feedback. The

With the use of a micropolarographic system, the effects of a series of isopropyl alcohol concentrations on oxygen uptake by the corneal epithelium of the rabbit were measured in vivo. Based on an exposure period of 10 sec, followed by a saline rinse, concentrations of greater than 31% were found to cause an abrupt and severe decline in oxygen uptake, with oxygen flux responses associated with 44% and greater being indistinguishable 60 min later from those of an epithelially denuded cornea. Initial flux variations, e.g. a mild depression at 24% and a mild elevation at just under 31%, were still evident 1 h following exposure. A slope model for estimating that concentration, the aerobic reduction dosage, which would reduce the oxygen flux activity of the epithelium to half, called here the ARD50, was found for this exposure time to be 37%. That estimate is in very close agreement with measured responses. A susceptibility ratio (SR), for comparing the relative toxicities of different agents based on the quotient of their ARD50 values, was calculated here for sodium hydroxide and isopropyl alcohol, and found to be 50:1.

Anesthesia is used to immobilize organisms for experiments and surgical procedures and to humanely mitigate pain. Despite its scientific importance, and though invertebrates seem to experience pain, overarching regulations for the application of anesthesia in invertebrate taxa do not exist. Indeed, the almost complete absence of legal requirements for invertebrate anesthesia might explain at least in part why there seems to have been little effort towards developing widely effective invertebrate anesthesia techniques. Here, we demonstrate that genetic differences between snails are a major driver of wide variation in menthol anesthesia success in an important freshwater snail model system, Potamopyrgus antipodarum. This is the first example of which we are aware of a role for genetic variation in anesthesia success in a mollusk. These findings both illuminate a potential mechanism underlying previously documented challenges in molluscan anesthesia and will set the stage for powerful and humane manipulative experiments in P. antipodarum.

Movement and demographic rates are critical to the persistence of populations in space and time. Despite their importance, estimates of these processes are often derived from a limited number of populations spanning broad habitat or environmental gradients. With increasing appreciation of the role fine-scale environmental variation in microgeographic adaptation, there is need and value to assessing within-site variation in movement, growth, and demographic rates. In this study, we analyze three years of spatial capture-recapture data collected from a mixed-use deciduous forest site in central Ohio, USA. Study plots were situated in mature forest on a slope and in successional forest on a ridge but were separated by less than 100-m distance. Our data showed that the density of salamanders was less on ridges, which corresponded with greater distance between nearest neighbors, less overlap in core use areas, greater space-use, and greater shifts in activity centers when compared to salamander occupying the slope habitat. However, these differences were moderate. In contrast, we estimated growth rates of salamanders occupying the ridge to be significantly greater than salamander on the slope. These differences result in ridge salamanders reaching maturity more than one year earlier than slope salamanders, increasing their lifetime fecundity by as much as 43%. The patterns we observed in space use and growth are likely the result of density-dependent processes, reflecting differences in resource availability or quality. Our study highlights how fine-scale, within-site, variation can shape population demographics. As research into the demographic and population consequences of climate change and habitat loss and alteration continue, future research should take care to acknowledge the role that fine-scale variation may play, especially for organisms with small home ranges or limited vagility.