A spatial framework for detecting anthropogenic impacts on predator-prey interactions that sustain ecological integrity in Mexico

Abstract

Background: This paper presents several spatial indicators developed to evaluate anthropogenic impacts on predator-prey interactions and their relationship with ecological integrity loss in Mexico. Ecological integrity loss is defined as the inability to sustain viable populations, habitat functions, and species interactions of Nearctic and Neotropical apex predators as a result of anthropogenic effects. As direct impacts, the indicators evaluate habitat loss and the number of inhospitable habitats. As indirect impacts, the indicators evaluate the avoidance of human features such as highways, roads, and human locations. The total impact level is described at 1 km2 resolution, and registered within the domain defined by the spatial habitat requirements of apex predators. The impact level is associated with ecological integrity loss, or the ecosystem capacity to reorganize habitat functions and sustain predator-prey interactions as the most visible elements of ecological integrity. Ecological integrity loss is evaluated for different groups of apex predators that are classified with different levels of anthropogenic threat. Results: The framework presented here identifies the spatial information needed for the assessment of cumulative anthropogenic impacts. By characterizing their distribution range, Nearctic predators have significantly larger intact habitats than neotropical predators but with higher ecological degradation, less landscape transformation, and overall less ecological integrity. As observed within their distribution areas, indirect impacts have a generalized effect in the broad range of landscapes in Mexico. Ecological integrity loss is the result of road, highway, and human settlement avoidance; but landscape transformation and human activity control the threshold for which ecological integrity loss becomes critical. On the other hand, there are no significant differences in impact levels among threat conservation categories for apex predators, which indicate that all predator species have the same threat level and should be all included in protection efforts. Conclusions: With the application of this spatial framework, the significance, scale, and baseline conditions can be established for evaluating anthropogenic impacts on ecological integrity. The analysis of the current condition shows the status for apex predator in the country, and identifies the ecological integrity threshold when human activities have severe to highly severe impacts in the landscape, threatening the viability of populations and their habitat.