So for the final chapter in our series of the three most important ecosystems, last but not least, is the coral reef.
What exactly is coral? Is it a rock? An animal? A plant?
Well corals are made of up lots and lots of individual coral polyps. And these polyps are animals. These individuals work together in symbiosis, in many cases sharing a skeleton, and passing food and nutrients between each other. Each polyp is a very simple structure, with an internal skeleton, a gut and a central mouth surrounded by tentacles. These tentacles will come out at night to feed, by capturing tiny zooplankton from the water. The bulk of their energy however, is obtained by tiny plant-like cells, called Zooxanthellae which live inside of their tissues. These zooxanthellae, just like other plants photosynthesise during the day, providing the coral with energy, and in-turn being provided protection and nutrients from their host.
These coral structures, which come in many different shapes and sizes, together make up the coral reef.
The coral reef has long fascinated humans. Located in crystal clear waters, surrounded by marine ‘desert’, which are usually nutrient bare locations, coral reefs are famous for their abundance of life and diversity. In fact, the coral reef is home to at least 25% of all marine fish, despite covering less than 0.1% of the planets oceans. The complex structure that the coral forms when it grows, provides lots of hidey-holes for marine creatures to live and hide in. Every creature on the reef plays its role, with some developing clever symbiotic relationships to survive. One famous example being the anemone-clownfish relationship. The iconic clownfish is provided protection by the stinging tentacles of the anemone, and in turn the clownfish protects the anemone by chasing away potential predators. Another famous examples include the cooperation between groupers and moray eels when hunting on the reef.
The reef is not only an important haven for the animals living there however; the coral reef is a vital source of protein for more than 100 countries, in addition to this, the economy of many countries – in particular the Maldives, rely on the reef economically, either through revenue of seafood sales, or through eco-tourism (snorkeling, diving etc). The reef is an important barrier for islands during storms and tsunamias, dramatically attenuating wave energy. Traditionally, in the Maldives coral was also used in the building of houses.
Coral reefs are under threat. Already is has been estimated that up to 90% of some reefs in the Great Barrier Reef have died. This is due to an event called coral bleaching, where the increasing temperatures of the ocean becomes very stressful for the coral, and the symbiotic algae in the coral is expelled. Without the energy gained from the zooxanthellae, the coral becomes even more weak, and if the temperatures do not return to normal quickly enough, the coral will eventually die. In addition to this, ocean acidification, due to increasing carbon dioxide in the atmosphere, means that the coral will not be able to calcify and build up their white limestone skeleton anymore, and eventually the reefs will begin to dissolved. Another problem this poses, is that it hinders the ability of coral to keep up with rising sea levels…
The greatest thing that WE can do to prevent the complete loss of this beautiful, complex and loved ecosystem, is to tackle climate change. Here are some simple ideas of what YOU can do:
- Avoid using energy unnecessarily – switch off your lights!
- Reduce your carbon footprint – walk more, fly less, and get involved with carbon credit schemes when you do take that unavoidable flight.
- Eat better – reducing your carbon footprint goes beyond just travel, 18% of greenhouse gas emissions come from dairy and meat production. Try giving vegetarianism a go… or if that’s too much for you, opt for 1 meat-free meal a day, and choose local produce where possible.
- Switch to renewable energy options – solar panels and wind farms are becoming increasingly popular and affordable.
- Lastly, spread the word! Encourage your friends, family and community to make these important changes too.
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