Estimating animal densities and home range in regions with irregular boundaries and holes: A lattice-based alternative to the kernel density estimator

Density estimates based on point processes are often restrained to regions with irregular boundaries or holes. We propose a density estimator, the lattice-based density estimator, which produces reasonable density estimates under these circumstances. The estimation process starts with overlaying the region with nodes, linking these together in a lattice and then computing the density of random walks of length k on the lattice. We use an approximation to the unbiased crossvalidation criterion to find the optimal walk length k. The technique is illustrated using walleye (Sander vitreus) radiotelemetry relocations in Lake Monroe, Indiana. We also use simulation to compare the technique to the traditional kernel density estimate in the situation where there are no significant boundary effects.     

Evaluating the effects of foraging habitat restoration on shorebird reproduction: the importance of performance criteria and comparative design

Coastal development and engineering projects preclude ecosystem processes that provide habitat for beach nesting birds. Management for coastal species may depend on actions that attempt to restore important habitat features and mitigate disturbance effects. However, species response to restoration or other management actions may be difficult to predict or measure. At Jones Beach State Park, on Long Island, New York, a 0.49 ha restoration project provided moist substrate foraging habitat for breeding Piping Plovers (Charadrius melodus) from 2002 to 2005. We examined whether foraging habitat restoration affected Piping Plover breeding population size, productivity, and fledgling production within 300 m of the restoration site. We found a positive relationship between habitat restoration and the number of fledglings produced per year. However, foraging habitat restoration did not significantly increase the number of Plover pairs breeding at Jones Beach. Our ability to evaluate restoration effects on Plovers depended on: 1) use of multiple performance criteria; 2) a design that allowed comparison of pre- and post-restoration data; and 3) a spatial control that allowed comparison of similar areas that were near and far from the restoration site. Despite the small size of the restoration project, there were measurable benefits to Plovers, indicating that foraging habitat restoration may be an effective tool for species recovery.     

Combining chemical sequential extractions with 3D fluorescence spectroscopy to characterize sludge organic matter

The design and management of anaerobic digestion of sewage sludge (SS) require a relevant characterisation of the sludge organic matter (OM). Methods currently used are time-consuming and often insufficiently informative. A new method combining chemical sequential extractions (CSE) with 3D fluorescence spectroscopy was developed to provide a relevant SS characterisation to assess both OM bioaccessibility and complexity which govern SS biodegradability. CSE fractionates the sludge OM into 5 compartments of decreasing accessibility. First applied on three SS samples with different OM stability, fractionation profiles obtained were in accordance with the latter. 3D fluorescence spectroscopy revealed that the bioaccessible compartments were mainly constituted of simple and easily biodegradable OM while the unaccessible ones were largely made of complex and refractory OM. Then, primary, secondary and anaerobically digested sludge with different biodegradabilities were tested. Complexity revealed by 3D fluorescence spectroscopy was linked with biodegradability and chemical accessibility was correlated with sludge bioaccessibility.     

Enhanced anaerobic bioremediation in a multicontaminant plume

The potential application of enhanced in situ bioremediation (EISB) for treatment of a plume containing high concentrations of 1,2‐dichloroethane (1,2‐DCA), as well as lower concentrations of other chlorinated ethanes, chlorinated methanes, and chlorinated ethenes was evaluated through the implementation of four field trials. The field trials confirmed that EISB is an effective technology for treating multiple contaminants, with estimated mass removal rates on the order of several kilograms per day and groundwater concentration reductions nearing 100 percent of the initial concentrations. The field trials also demonstrated that engineering controls could be effectively used to overcome potential inhibitions related to high concentrations of 1,2‐DCA. © 2008 Wiley Periodicals, Inc.     

Perils of using speed zone data to assess real-world compliance to speed limits

Objective: Real-world driving studies, including those involving speeding alert devices and autonomous vehicles, can gauge an individual vehicle's speeding behavior by comparing measured speed with mapped speed zone data. However, there are complexities with developing and maintaining a database of mapped speed zones over a large geographic area that may lead to inaccuracies within the data set. When this approach is applied to large-scale real-world driving data or speeding alert device data to determine speeding behavior, these inaccuracies may result in invalid identification of speeding. We investigated speeding events based on service provider speed zone data.

Methods: We compared service provider speed zone data (Speed Alert by Smart Car Technologies Pty Ltd., Ultimo, NSW, Australia) against a second set of speed zone data (Google Maps Application Programming Interface [API] mapped speed zones).

Results: We found a systematic error in the zones where speed limits of 50–60 km/h, typical of local roads, were allocated to high-speed motorways, which produced false speed limits in the speed zone database. The result was detection of false-positive high-range speeding. Through comparison of the service provider speed zone data against a second set of speed zone data, we were able to identify and eliminate data most affected by this systematic error, thereby establishing a data set of speeding events with a high level of sensitivity (a true positive rate of 92% or 6,412/6,960).

Conclusions: Mapped speed zones can be a source of error in real-world driving when examining vehicle speed. We explored the types of inaccuracies found within speed zone data and recommend that a second set of speed zone data be utilized when investigating speeding behavior or developing mapped speed zone data to minimize inaccuracy in estimates of speeding.     

Biota Connect Aquatic Habitats throughout Freshwater Ecosystem Mosaics

Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.     

Agri-environmental thresholds using Mehlich III soil phosphorus saturation index for vegetables in histosols

The P concentration in Norton Creek which drains cultivated Histosols in Quebec showed median concentration exceeding up to 14 times the environmental guideline of 0.03 mg total P L(-1). The aim of this study was to develop environmental and agronomic thresholds using soil tests to provide a tool for P management in Histosols. Soil samples were collected from Histosols across Quebec (82) and in fertilizer trials (66) to calibrate soil test methods against the degree of P saturation (DPS(OX)) using the acid-oxalate method and setting alpha(m) = 0.4, and the water-extractable P (P(W)) (Sissingh, 1971). The field trials on crop response to added P were conducted with carrots (8), potatoes (11), onions (10), Chinese cabbage (7), celery (10), and lettuce (20). Relative yields were computed as yield in control without P divided by highest yield with added P. The Mehlich III (M-III) P extraction was more closely related (r(2) = 0.73) to DPS(OX) than the Bray 1 method (r(2) = 0.62) and the Florida extraction method (r(2) = 0.53). The [P/(Al+gammaFe)](M-III) ratio as index of P saturation (IPS(M-III)) was the most closely related to DPS(OX) (r(2) = 0.88) setting gamma = 5. The critical [P/(Al+5Fe)](M-III) ratio of 0.05 at DPS(OX) = 0.25 and P(W) = 9.7 mg P L(-1) was validated by an independent study from North Carolina. The soil group (low- vs. high-IPS(M-III) soils) significantly influenced crop response to added P. Critical agronomic IPS(M-III) values were found between 0.10 and 0.15. Those environmental and agronomic benchmarks are instrumental for managing the P in vegetable-grown Histosols.