Rising sea temperatures threaten coral reefs

Satellites can tell us the surface temperature of the ocean, which is important for weather patterns, and lots of other elements of the environment. Sea surface temperature is monitored by the Ocean and Sea Ice SAF  and the European My Ocean project.

Coral reefs are an important part of the ocean ecosystem, but are very sensitive to sea temperature.

Corals, which grow in warm shallow waters, look like rocks or plants, but are actually small animals. They have a symbiotic relationship with algae that live inside them – this means both organisms rely on each other to survive.

Changes in the environment can cause the coral to eject the algae, and lose its colour in a process known as “bleaching”. If the algae do not return to the coral, it may not survive the bleaching.

This map from 5 December 2014 uses sea surface temperature data to show the risk to corals from unusually warm sea water over a period of time. If the temperature gets very high, or stays one degree warmer than the coral can tolerate for more than a month, the coral is in danger.

Degree heating weeks are shown in different colours - yellow corresponds to four degree heating weeks, rising to orange for eight degree heating weeks, and up to violet for 16 or more degree heating weeks. (map by NOAA Climate.gov)

Degree heating weeks are shown in different colours – yellow corresponds to four degree heating weeks (above this level, corals are at risk), rising to orange for eight degree heating weeks, and up to violet for 16 or more degree heating weeks. (map by NOAA Climate.gov)

 

Coral reefs are home to thousands of different species, and fish living on reefs are an important food source to many communities. The reefs also help to protect coastlines from storms and erosion.

You can read and hear more about coral bleaching in this NOAA podcast.

Warming sea water is not the only threat to coral reefs – pollution and overfishing can also cause damage, while naturally occurring storms can also affect the reefs.

Marine biologists and conservation groups are working to try to protect corals all around the world. These efforts include trying to avoid accidental damage to coral reefs by boats or divers, and working with communities on rivers that flow into the sea near coral reefs to reduce pollution.

You can read more from Joshua Drew here, or find out about the work of the Coral Reef Alliance on their website.

About the Author

Ruth McAvinia

Ruth McAvinia

Learning Zone Writer

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