1. Annual Dolphin census
• Annual Dolphin census was recently carried out in Odisha by the state’s forest and environment department.
• The census covered important aquatic ecosystems in the state including the Chilika lake, India’s largest brackish water lagoon, spread over the Puri, Khurda and Ganjam districts, the Gahirmatha Marine Sanctuary and its nearby areas within the Bhitarkanika National Park in Kendrapara district, Balasore district and the mouth of the Rushukulya River in Ganjam district.
• Population declined from 469 in 2018 to 259 this year. The reduction in the number of dolphins compared to last year could be due to the migration of species from the Chilika Lake and other water bodies to the deep sea.
• Gahirmatha is the home of the state’s largest dolphin population, having 126 animals. More dolphins were found in Gahirmatha than Chilika due to its bigger areas.
• After Gahirmatha, Chilika had the next largest population at 113, followed by the Rushukulya River in Ganjam district, with 15 dolphins and finally, Balasore, with 5 individuals.
• The dolphin species sighted during the state-wide census included the Irrawaddy, the Bottle Nose and the Humpback.
• Dolphins have been included in Schedule I of the Indian Wild Life (Protection) Act 1972, in Appendix I of the Convention on International Trade in Endangered Species (CITES), in Appendix II of the Convention on Migratory Species (CMS) and categorised as ‘Endangered’ on the International Union for the Conservation of Nature’s (IUCN) Red List.
2. Massive mountains in the Earth’s mantle
• Scientists have discovered massive mountains in the Earth’s mantle, an advance that may change our understanding of how the planet was formed.
• These newly discovered mountains are located between upper and lower mantle. Scientists used data from an enormous earthquake in Bolivia to find mountains and other topography on a layer located 660 km straight down, which separates the upper and lower mantle.
• Data from earthquakes that are magnitude 7.0 or higher sends shockwaves in all directions that can travel through the core to the other side of the planet — and back again.
• Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”
• The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and evolved.
• Earthquake waves are basically of two types – body waves and surface waves.
• Body waves: They are generated due to the release of energy at the focus and moves in all directions traveling through the body of the earth. Hence, the name – body waves. They travel only through the interior of the earth. Body waves are faster than surface waves and hence they are the first to be detected on a seismograph. There are two types of body waves as primary waves and secondary waves.
• Surface Waves: When the body waves interact with surface rocks, a new set of waves is generated called as surface waves. These waves move along the earth surface. Surface waves are also transverse waves in which particle movement is perpendicular to the wave propagation. Hence, they create crests and troughs in the material through which they pass.
• Surface waves are considered to be the most damaging waves. Two common surface waves are Love waves and Rayleigh waves.