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Bleaching Reefs and Us

Although tropical coral reefs don’t line New Zealand’s coasts it doesn’t mean we shouldn’t care about news of the Great Barrier Reef (GBR) and in particular the newest wave of coral bleaching to hit the area.

Although tropical coral reefs don’t line New Zealand’s coasts it doesn’t mean we shouldn’t care about news of the Great Barrier Reef (GBR) and in particular the newest wave of coral bleaching to hit the area.

Scientists are alarmed after the Great Barrier Reef in Australia is hit by the worst coral bleaching in its history.

Why should we care?

The GBR is one of the most diverse ecosystems in the world, it is home to over 600 coral species, 1600 fish species and a whole host of other important marine life (whales, turtles and sea birds to name a few). It may not be on the doorstep of any local kiwi beach but its vast complex ecosystem and its biodiversity make it globally significant and something we should all be aware of.

Hang on, what is coral bleaching?

Coral bleaching is when coral skeletons turn white, but it’s not just losing its colour.

Corals get up to 90% of their energy supply from the zooxanthellae that live within them. Stressful conditions (including high water temperature) cause the corals to expel their zooxanthellae. Bleached corals begin to starve once they bleach.

Coral have a symbiotic relationship with a tiny single celled microorganism called a Zooxanthelle, there are lots and lots of different types of coral Zooxanthelle and they live in different corals. Zooxanthelle photosynthesise and provide food and nutrients essential for the corals survival, in fact they produce 75-80% of the corals energy requirements.

Zoom into a coral reef and discover photosynthetic algae inside the coral’s cells. Reef-building corals rely on these symbionts for their survival. This stunning animation is perfect for all levels of biology and environmental science classes.

When environmental conditions are too harsh, for example too hot, the zooxanthelle will leave the coral polyp. If conditions return to a range that these organisms can live in, they may return. However, if conditions remain unfavourable or the conditions become harsh again quickly then the zooxanthelle might not return and the coral could die.

So why do the corals go white? Well, these organisms also give the coral its colour.

Perhaps we might view the GBR as a coralline canary in climate change coal-mine and maybe we should heed its warning signals. Why the warning? Well, the environmental changes causing coral bleaching will impact the 70% of the planet that is covered by ocean.

So what is causing the bleaching??

The short answer is climate change. More specifically increasing temperatures, in particular due to a strong El Niño weather event (the frequency and intensity of which are only predicted to increase with increased atmospheric carbon dioxide).

Why does this matter for New Zealand Waters?

Climate change is increasing ocean temperatures, making ocean waters more acidic and increasing storm and other climatic events (such as El Ninos) frequency and intensity. These changes are affecting us all, the distribution of fish is changing, causing knock on effects to marine food webs. Marine ecosystems are being pushed to their limits and things are changing in ways that scientists are finding hard to predict. For years, scientists have been warning about the effects of climate change on marine ecosystem but little has been done to change legislation. Watch this video for a more in-depth explanation of how climate change is impacting marine ecosystem.

This latest round of coral bleaching should act as a wake up call that changes are happening and they are happening fast. It is our global responsibility to address climate change and we really need to take this seriously otherwise we might lose some of the most beautiful environments in the world, put our own food supply in danger, and decrease the quality and habitability of our planet for our children and grandchildren. The time to act is now.

But how?

I agree with any who say they are fed up of hearing about the problems, because we need solutions. We need solutions that work and we need governments, industry and big business to take this seriously. So what can we do?

Learn, be informed, be aware, and make better choices and ask for more from those in positions of power.  More details are set out in these United Nations guidelines.

This collaborative video from the four research universities in British Columbia is great for telling us what climate change is and what we can do.

However, we must remember that we ALL have the power to make positive change, we just have to choose to do so. Sometimes these choices may seem inconvenient, but really all it takes is looking at the solutions from a different angle. We can do it, we can be the change, we can remember our connection to the natural environment and we, us, right here right now, could make the difference between a future where our grandchildren see the barrier reef and one where they just read about it.

These are our seas, this is our future.

More Information:

About the reef:

Most recent bleaching:

More about coral bleaching:

For more information about how climate change will impact New Zealand you can check out this interactive map:

A Report on climate change and New Zealands Marine Environment:

Video about climate change and New Zealand’s Marine Environment:

What we can do about climate change:

Contributor: Jennifer Cooper

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