Environmental contamination predicts mammal diversity and mesocarnivore
activity in the Seattle-Tacoma metro area
Abstract
In the era of the Anthropocene, the environmental factors controlling
the distribution and abundance of wildlife populations are increasingly
complicated by historical and ongoing urban development and
industrialization. The legacy of industrialization has enduring impacts
on contemporary environmental quality, with additional downstream
consequences for wildlife that reside in cities. However, industrial
contaminants are not evenly distributed across or within cities.
Further, while the long-term fitness consequences of environmental
contamination are well-documented for most taxa, their effects on
free-ranging wildlife at the population and community levels remain
poorly understood. Here, we investigated whether environmental
contamination risk from industrial pollutants was associated with
mammalian diversity and mesocarnivore activity in the Seattle-Tacoma
metropolitan area, Washington, USA, a historically industrialized
region. Using camera trap data collected across 74 sites and
pre-existing data from the Washington Environmental Health Disparities
Map, we modeled environmental contamination risk, natural land cover,
and human population density against mammalian community diversity,
richness, and evenness. We also modeled activity rates of three common
mesocarnivore species (coyotes, raccoons, and Virginia opossums) via the
number of detections. We found that mammalian diversity and evenness
decreased as contamination risk increased, especially in Seattle. Among
mesocarnivores in Seattle, coyote activity was negatively associated
with contamination risk, while raccoon activity was positively
associated with contamination risk; opossums showed no response.
However, in Tacoma, contaminant risk was not significantly associated
with mammalian biodiversity or activity; instead, human population
density emerged as the most important predictor, with a negative
influence on coyote activity and a positive influence on opossum
activity. Our results highlight the importance of considering the legacy
effects of industrialization and their impact on environmental quality
in urban wildlife camera trap studies, and the need for species- and
city-specific approaches in understanding the role environmental quality
plays in shaping urban wildlife communities.