Comparing amphibian habitat quality and artificial light at night (ALAN) between natural and restored vernal pools

Background/Question/Methods This light pollution study builds upon a multiyear wetland restoration ecology project in Pennsylvania and New Jersey. The overall goal is to compare various aspects of habitat quality between restored and natural vernal pools using successful reproduction and metamorphosis of the wood frog, an obligate vernal pool breeding amphibian, to measure desired outcomes. The vernal pool sites vary in their proximity to roads, housing developments, and cities, and therefore also in their exposure to ALAN. This observation inspired the following questions: 1) how do intensity and composition of night lighting compare among vernal pools sites and 2) how does ALAN (i.e., skyglow, vehicular lights, and streetlights) effect wood frog growth and development? Sky brightness, spectral irradiance, and vehicle frequency were measured at the vernal pool sites, and will be used to inform a laboratory experiment to quantify the effect of ALAN on wood frog growth and development under four conditions: no ALAN (control), simulated vehicular light pollution, simulated skyglow, and combined simulated vehicular light pollution and skyglow. Results/Conclusions Multivariate analysis of wood frog habitat determinants suggest that practitioners aiming to restore functional vernal pools should focus on the relationship between pool volume and hydroperiod, surrounding forest cover, and proximity to natural pools, as these factors are more closely related to wood frog success than others. Preliminary results of the light pollution component of this study indicate that project sites are being exposed to moderate amounts of light pollution. Skyglow ranges from 19.41 to 20.62 magnitudes per square arcsecond, and although spectral composition of night sky brightness appears consistent among sites, irradiance ranges from 0.0001 to 0.005 micromoles/m2/s with variations in intensity influenced by cloud and canopy cover. In comparison to vernal pools near Galeton, PA (an area notorious for its dark skies and small population), project pools are on average exposed to headlights from 51 more vehicles per night and greater than a 6-fold increase in sky brightness.