Warming Waters

As the oceans warm, some fish species are migrating away from equatorial waters towards cooler areas closer to the poles

These changes in distribution will:

Impact delicately balanced ecosystems in which each species plays a vital role


Have consequences for coastal communities in equatorial regions who rely on fish for livelihoods

What is Coral Bleaching?

Higher temperatures are also leading to an increase in large-scale, prolonged, coral bleaching events. Coral bleaching is one of the most visual indicators of thermal stress due to climate change.

Corals exist in a symbiotic relationship with microscopic algae called zooxanthellae that live in the corals’ tissues and, through a process of photosynthesis, produce vital food for the coral polyps

When water temperatures are consistently too warm, the corals and zooxanthellae become stressed. The zooxanthellae will leave their coral hosts. The coral loses its colour, turning white. This will normally happen over a period of 4–6 weeks

If water temperatures do not drop, the coral will starve and die. The remaining skeleton will be colonised by algae, making it impossible for the coral to recover

Coral reefs that are already stressed are more vulnerable and less able to recover from bleaching events. Other stresses for coral reefs include:

What Is El Niño And What Does It Have To Do With Coral Bleaching?

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. The presence of El Niño can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the globe for an extended period of time. Combined with warmer-than-average water temperatures, El Niño events are likely to have increasingly dramatic and severe impacts.

Read the rest of this article in 2017 Issue 1 Volume 144 of Asian Diver magazine by subscribing here or check out all of our publications here.

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