Environment and ecology
New freshwater crab genus identified
- Scientists have identified a new genus and species of freshwater crab from the Shevaroy Hills, Yercaud (Salem district, Tamil Nadu).
- The newly described genus is Patithelphusa, and the species is Patithelphusa yercaudensis.
- The discovery was made during a zoological survey by researchers from the Zoological Survey of India (ZSI), Kolkata, and Pukyong National University, South Korea.
- The genus Patithelphusa is named in honour of Sameer Kumar Pati, a distinguished Indian taxonomist known for his work on freshwater crabs.
- Distinct features: broader carapace, triangular lobes, and unique male reproductive structures, differing from related genera like Baratha, Vanni, and Vela.
- The species’ evolution was likely influenced by topographical isolation of the Shevaroy Hills, separated by deep valleys and the Cauvery River system, which limited gene flow.
- Highlights the Shevaroy Hills as a potential refuge for endemic species in the Eastern Ghats.
- With this discovery, India now records 112 freshwater crab species, belonging to 31 genera under the family Gecarcinucidae.
- India contributes nearly 10% of the world’s freshwater crab diversity, with many species endemic to small habitats.
Cloud Seeding
- On October 28, 2025, IIT-Kanpur conducted a cloud seeding experiment over New Delhi using a Cessna aircraft, aiming to reduce air pollution through artificial rain.
- The team dispersed 10 kg of a mixture of silver iodide (20%), rock salt, and common salt, fired into the clouds using flares manufactured in Sivakasi, Tamil Nadu.
- IMD shared general weather inputs but did not recommend proceeding due to insufficient cloud moisture (<15%).
About Cloud Seeding
- Cloud seeding is a weather modification technology that artificially stimulates rainfall by spraying chemical substances into the air that serve as cloud condensation nuclei.
- It involves dispersing substances such as silver iodide, potassium iodide, sodium chloride, or dry ice (solid CO₂) into clouds using aircraft.
- Weather Suitability: It requires tall, moist clouds and low wind conditions to operate effectively.
- Pollution Removal: Artificial rain reduces particulate matter by washing pollutants out of the air.
- The India’s Ministry of Earth Sciences (MoES) has conducted several studies under the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX).
- States like Maharashtra, Karnataka, Andhra Pradesh, and Tamil Nadu have experimented with cloud seeding for drought relief.
Significance:
- First cloud seeding attempt in Delhi since 1972.
- First-ever trial aimed at pollution control rather than rainfall augmentation.
- Highlights the experimental and uncertain nature of cloud seeding under Indian climatic conditions.
