Do Spatially Explicit Wildlife Exposure Models Improve the Estimation of Risk for Small Mammals? Case Study: Application of Spatially Explicit Exposure Model to Small Mammal Exposures to Lead in Heterogeneous Landscapes.

Understanding risks to terrestrial wildlife species from exposure to chemicals in the environment requires knowledge of how species make habitat decisions and how subsequent exposure events occur. Heterogeneity of chemical distribution and of habitat quality can influence exposure. Previous studies in birds have shown that individually based, spatially explicit models can be useful in predicting exposure and risk; however, studies investigating these influences in small mammals with limited ranges have been lacking. Here we test a spatially explicit, individually based exposure model (Spatially Explicit Exposure Model [SEEM]) in which model predictions based on life history traits, habitat preferences, and varying soil Pb concentrations are used and compared to those with field-collected blood or tissue Pb concentrations in small (e.g., Peromyscus, Blarina spp.) and medium-sized mammalian species (e.g., Lepus spp.) at 3 Pb-contaminated sites. These species were chosen because they were expected to be present in suitable habitat, and Pb was modeled when adequate tissue-based toxicity thresholds were available. Oral exposure estimates from SEEM were compared with a traditional deterministic model and with field-collected tissue Pb concentrations using ecological hazard quotients (EHQs) to normalize between oral and real-time tissue Pb concentrations. Ecological hazard quotients at the 90% population effect level (for SEEM) and at the 95% upper confidence level (assuming a single Pb concentration with no consideration of habitat quality in the deterministic model) were compared with maximum EHQs developed from blood or tissue Pb concentrations. Deterministic estimates and SEEM were similar for small mammal species, yet slightly overpredicted risk compared to field tissue or blood Pb data. Estimates for hares (medium-sized mammals) using SEEM provided more accurate predictions compared with field tissue data. These data suggest that spatially explicit models may be sensitive to grain size, given that small mammals experience the environment in limited spatial contexts, a scale at which habitat may not change significantly. Integr Environ Assess Manag 2021;17:259-272. Published 2020. This article is a US Government work and is in the public domain in the USA.

Modeling aesthetics to support an ecosystem services approach for natural resource management decision making.

This paper reviews literature on aesthetics and describes the development of vista and landscape aesthetics models. Spatially explicit variables were chosen to represent physical characteristics of natural landscapes that are important to aesthetic preferences. A vista aesthetics model evaluates the aesthetics of natural landscapes viewed from distances of more than 1000 m, and a landscape aesthetics model evaluates the aesthetic value of wetlands and forests within 1000 m from the viewer. Each of the model variables is quantified using spatially explicit metrics on a pixel-specific basis within EcoAIM™, a geographic information system (GIS)-based ecosystem services (ES) decision analysis support tool. Pixel values are "binned" into ranked categories, and weights are assigned to select variables to represent stakeholder preferences. The final aesthetic score is the weighted sum of all variables and is assigned ranked values from 1 to 10. Ranked aesthetic values are displayed on maps by patch type and integrated within EcoAIM. The response of the aesthetic scoring in the models was tested by comparing current conditions in a discrete area of the facility with a Development scenario in the same area. The Development scenario consisted of two 6-story buildings and a trail replacing natural areas. The results of the vista aesthetic model indicate that the viewshed area variable had the greatest effect on the aesthetics overall score. Results from the landscape aesthetics model indicate a 10% increase in overall aesthetics value, attributed to the increase in landscape diversity. The models are sensitive to the weights assigned to certain variables by the user, and these weights should be set to reflect regional landscape characteristics as well as stakeholder preferences. This demonstration project shows that natural landscape aesthetics can be evaluated as part of a nonmonetary assessment of ES, and a scenario-building exercise provides end users with a tradeoff analysis in support of natural resource management decisions. Integr Environ Assess Manag 2017;13:926-938. © 2017 SETAC.

Global assessment of cadmium concentrations in the skin of free-ranging sperm whales (Physeter macrocephalus).

Cadmium is a non-essential, toxic metal found accumulated in the organs of stranded cetaceans. Currently, there is no baseline cadmium concentration reported in a free-ranging, pelagic cetacean. The aim was to determine cadmium concentrations in the skin of free-ranging sperm whales (n=340) collected from 16 regions around the world during the voyage of the Odyssey (2000-2005) considering region, gender, and age in males. Cadmium was detected in 81% of skin biopsies with a mean of 0.3±0.04µg/g ww (0.02 to 12.4µg/g ww). These concentrations were higher than reported in literature in toothed whale skin (0.002-0.1µg/g ww). Concentrations by region were significantly different (p<0.0001) with the highest mean in Maldives and the Sea of Cortez (0.8 and 0.6µg/g ww, respectively). There was no significant difference in cadmium concentration by gender (p=0.42). Cadmium is known to have a long biological half-life, and cadmium concentrations in males were significantly higher in adults with a mean of 0.3µg/g ww compared to subadults with 0.2µg/g ww (p=0.03). Selenium, an element that binds to cadmium inhibiting its toxicity, had a moderately positive correlation with cadmium (r=0.41). Mercury, a toxic metal that positively correlates with cadmium in cetacean tissue, had a weakly positive relationship (r=0.20). The regional baselines reported in this study may be used to develop residue criteria for prediction of toxicological risk in sperm whale skin. Additionally, this study shows the extent of cadmium exposure in a pelagic cetacean that has global distribution.