Effects of environmental change on wildlife health

Abstract

Environmental change has negatively affected most biological systems on our planet and is becoming of increasing concern for the well-being and survival of many species. At an organism level, effects encompass not only endocrine disruptions, sex-ratio changes and decreased reproductive parameters, but also include teratogenic and genotoxic effects, immunosuppression and other immune-system impairments that can lead directly to disease or increase the risk of acquiring disease. Living organisms will strive to maintain health by recognizing and resolving abnormal situations, such as the presence of invading microorganisms or harmful peptides, abnormal cell replication and deleterious mutations. However, fast-paced environmental changes may pose additional pressure on immunocompetence and health maintenance, which may seriously impact population viability and persistence. Here, we outline the importance of a functional immune system for survival and examine the effects that exposure to a rapidly changing environment might exert on immunocompetence. We then address the various levels at which anthropogenic environmental change might affect wildlife health and identify potential deficits in reproductive parameters that might arise owing to new immune challenges in the context of a rapidly changing environment. Throughout the paper, a series of examples and case studies are used to illustrate the impact of environmental change on wildlife health.

Figure 1.

Epidemiological triad. Occurrence of disease results from the interaction between host, environment and disease-agent components (e.g. pathogen or a chemical, UV radiation). Critical host components might be age, sex, genetic background, nutritional and physiological status or prior immune exposure to a pathogen. Environmental host components include climate, interaction with other species, densities and aggregation indexes. Each of the three components can alter the others (e.g. a particular climate regime may decrease food availability, thus changing the nutritional status of an individual or may allow a pathogen to be established in a new area or host). In the context of a rapidly changing environment (black circle), all three components will be subject to changes which will, in turn, alter the epidemiological triad.

Figure 2.

Potential effects of anthropogenic environmental change on wildlife health. The illustration intends to depict the intricate and multiple ways by which changes to the environment can affect health. Regardless of the level at which the changes occur (environmental, climatic and ecological), these will in turn alter other physical and biological processes, eventually increasing the risk of starvation, and exposure to diseases. At an individual level, environmental changes will affect health by weakening immune responses, impairing development and causing systemic disease or cancer.