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Amphibians constitute the most threatened major taxon on Earth today. Their dependence on cutaneous respiration necessitates a thin, moist, permeable skin that makes them vulnerable to desiccation, toxic chemicals, endocrine disruptors and changes in their physical environment. The seasonal migration of many species between terrestrial habitats and aquatic breeding sites exposes them to hazards such as increased risk of predation, traversing of inhospitable habitats and automobile traffic. Invasive species and destruction and fragmentation of habitat are implicated in some declines and humans collect amphibians for food, pets, research and medicines. Although amphibians cutaneously secrete a wide variety of antibiotics (Erspamer, 1994), they are susceptible to some viral, bacterial, parasitic and fungal infections. Thus, the alarming rate of decline and extinction of amphibians globally is not caused by a single agent (Halliday, 2005), but by a suite of them that vary geographically (Stuart 'et al'., 2010), and interact with each other. Changes in global climate have exacted a toll on amphibians already and are projected to be increasingly severe in the future. The present chapter reviews the causes of global decline and extinction of amphibians around the world. The reasons vary from one place to another. |
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