| Living coral reefs are foundation for many marine species and thus a crucial support for human life. What are the factor responsible for 'Coral bleaching'? |
| 1. Salinity |
| 2. Tide |
| 3. El-Nino |
| 4. Global warming |
| Select the correct answer using the codes given below. |
A) 1 and 2
B) 1, 2 and 4
C) 1 and 4
D) All of these
Correct Answer: D
Solution :
[d] The main cause of coral bleaching is heat stress resulting I from high sea temperatures. Tempe rature increases of only one degree Celsius for only four weeks can trigger bleaching events. Higher sea temperatures from global warming causes major coral bleaching events. Bleaching occurs when corals respond to the stress of warmer temperatures by expelling the colourful algae that live within them. High water temperatures can affect reefs at regional and global scale, further tides also damages corals because of their impact and varying temperature of tides. For intertidal corals, exposure to cold winds is damaging. The coral bleaching and disease, brought on by climate change (global warming) and coupled with events like the current EI-Nino, are the largest and most pervasive threats to coral reefs around the world. Other stressors can also cause bleaching, including freshwater inundation (low salinity) and poor water quality from sediment of pollutant run-off. Pollution from urban or agricultural run-off, changes in the salinity, or saltiness of seawater, sedimentation from undersea activities like dredging and other factors include an increase in solar radiation (UV and visible light). If
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