Marine Heat Waves

Table of Contents

About Marine Heat Waves (MHWs)

It is an extreme weather event which occurs when the surface temperature of a particular region of the sea rises to 3 or 4 degree Celsius above the average temperature for at least 5 days.
MHWs can last for weeks, months or even years.
Impacts of MHWs:
- Coral
- Reason behind MHWs in this zone:
  - It is primarily driven by Eddy currents.
  - Eddy currents are large, swirling loops of water that transport warm or cold water over long distances.
- As ocean temperatures rise due to global warming, these currents carry warmer surface water down into the twilight bleaching
- Harmful algal blooms
- Kelp and seagrass dieback
- Increased Hurricanes, Cyclones and more destructive flooding.

It lies just below the sunlit zone at a depth of 200 to 1,000 metres.
This zone contains a unique ecosystem, including plankton, fish and other marine organisms that form the base of the oceanic food web.
- It is also known as the mesopelagic zone, leading to increased temperatures.