Heat stress and amphibian immunity in a time of climate change

Abstract

As a class of vertebrates, amphibians, are at greater risk for declines or extinctions than any other vertebrate group, including birds and mammals. There are many threats, including habitat destruction, invasive species, overuse by humans, toxic chemicals and emerging diseases. Climate change which brings unpredictable temperature changes and rainfall constitutes an additional threat. Survival of amphibians depends on immune defences functioning well under these combined threats. Here, we review the current state of knowledge of how amphibians respond to some natural stressors, including heat and desiccation stress, and the limited studies of the immune defences under these stressful conditions. In general, the current studies suggest that desiccation and heat stress can activate the hypothalamus pituitary–interrenal axis, with possible suppression of some innate and lymphocyte-mediated responses. Elevated temperatures can alter microbial communities in amphibian skin and gut, resulting in possible dysbiosis that fosters reduced resistance to pathogens. This article is part of the theme issue ‘Amphibian immunity: stress, disease and ecoimmunology’.

Physiological processes through which heatwaves threaten fauna biodiversity

“…Correspondingly, metabolic traits at multiple biological hierarchies, such as mitochondrial structures (e.g., membrane components) and functions (e.g., mitochondrial respiration), and metabolic enzyme activities [e.g., hexokinase (HK), citrate synthase (CS), succinate dehydrogenase (SDH), cytochrome C oxidase (COX), and ATPase], are robust indicators for assessing energetic status under heatwaves. 3…”

Introduction to the special issue Amphibian immunity: stress, disease and ecoimmunology

“…Several papers in this issue describe stress-induced immunomodulation and causal effects of experimental increases in corticosterone on anurans. A review, [ 72 ], summarizes effects of heat and dehydration on amphibian immunity, highlighting the importance of these two stressors for amphibian survival. Studies suggest that heat and desiccation stress can activate the hypothalamus–pituitary–interrenal axis, resulting in increased corticosterone plasma levels, with possible immune suppression of some innate and lymphocyte-mediated responses.…”

“…Studies suggest that heat and desiccation stress can activate the hypothalamus–pituitary–interrenal axis, resulting in increased corticosterone plasma levels, with possible immune suppression of some innate and lymphocyte-mediated responses. In addition, increased temperatures can alter microbial communities in amphibian skin and gut, resulting in potential dysbiosis that fosters reduced resistance to pathogens [ 72 ].…”

“…Considering that amphibians face many threats, including habitat degradation, introduced species, pollutants, emerging diseases, unpredictable temperature changes and rainfall, [ 72 ] reviews amphibians' response to some natural stressors. The authors demonstrate that in addition to possibly suppressing some innate and lymphocyte-mediated responses, elevated temperatures can alter amphibian skin and gut microbial communities, resulting in possible dysbiosis that fosters reduced resistance to pathogens.…”

“…The authors demonstrate that in addition to possibly suppressing some innate and lymphocyte-mediated responses, elevated temperatures can alter amphibian skin and gut microbial communities, resulting in possible dysbiosis that fosters reduced resistance to pathogens. Thus, extreme heat and drought stresses due to climate change might increase the vulnerability of amphibians to diseases such as chytridiomycosis and ranavirus outbreaks [ 72 ]. The authors emphasize the importance of understanding host–pathogen physiology for determining how amphibian populations deal with stressful situations and cope with diseases in a changing world.…”