Dc track edge interactions

Includes bibliographical references.We have developed an experimental method for investigating the interaction between two dc track edges by studying the track edge noise. We conclude that two edges do not interact when they are several micrometers apart, but the noise reduces nearly to zero when their separation is less than about half a micrometer. There is a transition region that exists between these two limits. The net track edge noise power from two dc edges is quantized, implying that in our experiment track edges interact around the complete revolution of the disk or not at all.This work was supported in part by NSF Grant No. ECS-880470 and NSF Presidential Young Investigator Award (Indeck) ECS-89-5714

Citizen science reveals widespread negative effects of roads on amphibian distributions

Landscape structure is important for shaping the abundance and distribution of amphibians, but prior studies of landscape effects have been species or ecosystem-specific. Using a large-scale, citizen science-generated database, we examined the effects of habitat composition, road disturbance, and habitat split (i.e. the isolation of wetland from forest by intervening land use) on the distribution and richness of frogs and toads in the eastern and central United States. Undergraduates from nine biology and environmental science courses collated occupancy data and characterized landscape structure at 1617 sampling locations from the North American Amphibian Monitoring Program. Our analysis revealed that anuran species richness and individual species distributions were consistently constrained by both road density and traffic volume. In contrast, developed land around wetlands had small, or even positive effects on anuran species richness and distributions after controlling for road effects. Effects of upland habitat composition varied among species, and habitat split had only weak effects on species richness or individual species distributions. Mechanisms underlying road effects on amphibians involve direct mortality, behavioral barriers to movement, and reduction in the quality of roadside habitats. Our results suggest that the negative effects of roads on amphibians occur across broad geographic regions, affecting even common species, and they underscore the importance of developing effective strategies to mitigate the impacts of roads on amphibian populations

Passive Acoustic Gliders Are Effective Monitoring Tools for Dynamic Management Plans Aimed at Mitigating Whale‐Vessel Strikes

ABSTRACT Dynamic management is intended to mitigate the impacts of human activities on wildlife when and where the activities overlap with at‐risk species. Amid an ever‐growing maritime industry, we researched the performance of mobile underwater passive acoustic gliders as near real‐time monitoring assets for the purpose of whale‐vessel strike mitigation through dynamic management. Across 580 glider survey days, 30 near real‐time acoustic detections of critically endangered North Atlantic right whales (NARWs) triggered 194 days of mandatory 10‐knot vessel speed limits in three Canadian Dynamic Shipping Zones (DSZs). We found a high degree of interannual and seasonal variation in NARW acoustic occurrence and vessel slowdowns in the DSZs. Gliders were more effective than aerial surveillance at triggering slowdowns by a factor of 2–5 during fall and summer but were less effective during spring. Our results provide unambiguous evidence that gliders are effective monitoring platforms that can enhance dynamic ocean management goals globally