Second Global Amphibian Assessment Report

Source: Down To Earth
GS III: Environment

Overview

1. News in Brief
2. About the Report
3. What are Amphibians?

Why in the News?

A new paper analysing two decades of data from around the world has found that climate change is emerging as one of the biggest threats to frogs, salamanders, and caecilians.

News in Brief

• The study titled Ongoing Declines for the World’s Amphibians in the Face of Emerging Threats was published in the scientific journal.
• Climate change is the new driver pushing the amphibian population towards extinction, a new study showed.

About the Report

• Frogs, caecilians, and salamanders are examples of amphibians, which are currently the most endangered animals on earth.
• Out of the 8,011 species of amphibia that have been evaluated so far, more than 40% are threatened with extinction.
• Globally, their situation is becoming worse.
• In the years 1980 to 2004, disease and habitat loss posed a danger to 91% of the amphibian species.
• Climate change and habitat loss are the main causes of the status degradation of 39% and 37% of the investigated species, respectively, between 2004 and 2023.
• 60% of the endangered species have been shown to be declining due to fungi infections and climate change.
• A unique non-invasive diagnostic method for finding the fungus pathogen has been developed by CSIR-CCMB.
• The highest concentration of threatened species was mapped to be located in India’s Western Ghats, Sri Lanka, Madagascar, Caribbean islands, tropical Andes, Mesoamerica and the mountains and forests of western Cameroon and eastern Nigeria.
• Other geographic locations of high concentrations included the Atlantic Forest biome of southern Brazil, central and southern China and the southern Annamite Mountains of Vietnam.
• The second most threatened group of vertebrates included cycads which faced a 69 per cent threat; sharks and rays faced 37.4 per cent threat, conifers faced 34 per cent, reef-building corals 33.4 per cent, mammals 26.5 per cent and reptiles 21.4 per cent.
• 48 per cent were classified as enigmatic decline species.
  • Diseases such as chytridiomycosis, caused by Batrachochytrium dendrobatidis, were mainly responsible for many enigmatic declines.

Improved Status

• 120 species improved their Red List status since 1980.
• 63 species improved their status directly due to conservation action such as habitat protection and management from countries like Costa Rica and Sabah in Malaysia and the Western Ghats in India.

What are Amphibians?

Amphibians are a class of vertebrate animals known for their unique life history that involves two distinct life stages: an aquatic larval stage and a terrestrial adult stage.

They are characterized by several key features

• Moist Skin
  • Amphibians have thin, permeable skin that lacks scales or feathers.
  • This skin is highly sensitive to desiccation (drying out), so they are often found in moist environments.
  • Many amphibians can breathe through their skin, which is especially important for respiration in aquatic species.
• Metamorphosis
  • Amphibians undergo metamorphosis, which means they go through a dramatic physical transformation as they transition from aquatic larvae to terrestrial adults.
  • For example, frogs start as tadpoles with gills and a tail, and they eventually develop legs, lose their tails, and develop lungs for breathing air.
• Dual Respiration
  • Amphibians typically respire through both their skin and their lungs.
  • Larval amphibians often respire primarily through gills, while adults rely more on lungs.
  • However, many adult amphibians still have moist, permeable skin that aids in gas exchange.
• Ectothermic
  • Amphibians are ectothermic, which means their body temperature is regulated by the external environment.
  • They cannot generate their own body heat as mammals and birds do.
  • Consequently, they are often more active in warm, moist conditions.
• Habitats
  • Amphibians are found in a variety of habitats, including freshwater ponds, streams, rainforests, and terrestrial ecosystems.
  • They are especially abundant in areas with access to both aquatic and terrestrial environments.
• Species Diversity
  • There is a wide range of amphibian species, including frogs, toads, salamanders, and newts.
  • Frogs and toads belong to the order Anura, while salamanders and newts are part of the order Urodela.
  • These groups exhibit diverse adaptations and behaviours.

Conclusion

• Amphibians play essential roles in ecosystems.
• They are both predators and prey, and they contribute to nutrient cycling.
• However, many amphibian species are currently facing population declines and extinction threats due to factors like habitat loss, pollution, climate change, and a fungal disease called chytridiomycosis.
• Conservation efforts are underway to protect these unique and ecologically important animals.

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