Context:
World Frog Day (March 20) highlights the ecological importance of frogs, the most numerous group of amphibians. Despite their vital role, they are currently the most threatened vertebrate group globally, according to the IUCN.
1. Ecological Significance of Frogs
- Interface Species: They bridge the gap between freshwater and terrestrial ecosystems.
- Biomass Conversion: They play a critical role in converting insect biomass (by eating insects) into vertebrate biomass (by being eaten by birds, reptiles, and mammals).
- Pest Control: They act as natural biological controllers of agricultural pests.
- Ecosystem Indicators: Their permeable skin makes them highly sensitive to environmental changes (pollution, climate), acting as “ecological sentinels.”
2. Major Threats to Amphibians
- Chytridiomycosis: A devastating fungal disease caused by:
- Batrachochytrium dendrobatidis (in frogs).
- Bactrachochytrium salamandrivorans (in salamanders).
- Mechanism: It attacks the skin, disrupting respiration and electrolyte balance.
- Origin: Asia (spread globally via the pet trade and frog leg exports).
- Climate Change (39%): Now the leading driver of extinction. It causes a “seasonal mismatch” (e.g., false monsoon cues followed by droughts).
- Habitat Loss (37%): Significant threat due to land-use changes.
3. The Indian Scenario
- Diversity: India is home to over 450 amphibian species.
- Conservation Status: Roughly 1/4th are ‘Threatened’.
- 1/5th are ‘Data Deficient’ (lack of long-term monitoring).
- Legal Protection: Out of 157 threatened species, only six are protected under the Wildlife Protection Act, 1972.
- Regional Trends: Mass mortality due to fungi is lower in India compared to the Americas/Australia, likely because the fungi originated in Asia.
4. Key Conservation Initiatives in India
- Jorepokhri Salamander Sanctuary (WB): Created in 1985 for the Himalayan Salamander.
- Dissection Ban: In 2011, the UGC banned the dissection of frogs for educational purposes.
- Breeding Programmes:Padmaja Naidu Himalayan Zoological Park (Darjeeling): Conservation breeding for the Himalayan Salamander.
- Tillari Conservation Reserve (Maharashtra): Long-term monitoring of stream frogs.
- Citizen Science Projects:Mapping Malabar Tree Toad Project (Western Ghats).
- Amphibian Recovery Project (Munnar, Kerala).
- iNaturalist: A portal for citizens to share photographs and recordings of frogs.
5. Important Biological Facts for Prelims
- Metamorphosis: The transition from aquatic tadpoles (algae eaters) to terrestrial froglets/adults (insect eaters).
- Skin Functions: In amphibians, the skin is an organ for protection, respiration, and ion exchange (electrolyte balance).
- IUCN Assessment: The 2023 Global Amphibian Assessment confirmed 37 species have gone extinct recently.
With reference to frogs, consider the following statements:
1. They act as an interface between freshwater and terrestrial ecosystems.
2. They convert plant biomass directly into vertebrate biomass.
3. They are considered ecological indicators due to their permeable skin.
Which of the statements given above is/are correct?
(a) 1 and 3 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3
Answer: a
The correct answer is (a) 1 and 3 only.
Detailed Explanation:
• Statement 1 is correct: Frogs are known as "interface species." They spend part of their life cycle in water (as eggs and tadpoles) and part on land (as adults). This allows them to link freshwater and terrestrial ecosystems, facilitating the flow of energy and nutrients between the two environments.
• Statement 2 is incorrect: According to the article provided, frogs eat insects and are then eaten by other vertebrates. Therefore, they are crucial in converting insect biomass into vertebrate biomass, not plant biomass directly. While tadpoles may eat algae (plant matter), the primary ecological role highlighted for frogs in the food chain is the consumption of insects.
• Statement 3 is correct: Frogs are excellent ecological indicators (or "sentinel species"). Their permeable skin allows them to breathe and exchange ions, but it also makes them highly susceptible to absorbing toxins, pollutants, and pathogens (like the Chytrid fungus) from their environment. A decline in frog populations often signals an early warning of environmental degradation.
