general knowledge refresher Published this article page no 98 Coral reefs are threatened by climate change. When the sea surface temperature increases beyond a tolerable limit they undergo a process of bleaching. What is bleaching? Basically bleaching is when the corals expel a certain algae known as zooxanthellae which lives in the tissues of the coral in a symbiotic relationship. About 90% of the energy of the coral is provided by the zooxanthellae which are endowed with chlorophyll and other pigments. They are responsible for the yellow or reddish brown colours of the host coral. In addition the zooxanthellae can live as endosymbionts with jellyfish also. When a coral bleaches it does not die but comes pretty close to it. Some of the corals may survive the experience and recover once the sea surface temperature returns to normal levels. Disaster and management. 1. What are cluster bombs and thermobaric weapons? Context Russia has resorted to the use of dangerous thermobaric bombs — or vacuum bombs — in Ukraine. 172 Cluster weaponry has been banned by the 2008 Convention on Cluster Munitions however neither Ukraine nor Russia were signatories at the convention. Thermobaric weapons These are called vacuum bombs as they suck in oxygen from surrounding areas to generate highvoltage explosions. The blast wave is of a greater intensity and duration than conventional bombs and can vapourise humans. While they cannot be used in taking down tanks and other such military vehicles they can dismantle civilian spaces like residential or commercial complexes. Cluster bombs Cluster munitions are nonprecision weapons that are designed to injure or kill human beings indiscriminately over a large area and to destroy vehicles and infrastructure such as runways railway or power transmission lines general knowledge refresher buy.
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