Article by Sarah Penington, winner of the 12-13 age group in the Oxfordshire Science Writing Competition 2002. Read this article about coral reefs and the threats to their survival, by a young Oxfordshire science writer.

Introduction

Coral reefs are one of the most beautiful environments on our planet. They are the rainforests of the seas with huge biodiversity- not only fish live in them, but starfish, crabs, sea anemones and many more animals that have not yet been discovered are there too. Tourists flock to see them and scientists study the creatures that live there - including the coral itself. Most people believe that coral reefs are well preserved and will be here ‘forever', still pristine and perfect, but it is really quite a different story.

Starfish, one of a coral reef's diverse inhabitants.

Sections in this article

How a reef is made

Threats to coral

Where Next?

  

How a reef is made

Coral is made by tiny animals, who build protective coverings for themselves, using chemicals from the sea which they turn into limestone. The delicate floral patterns that we know as coral are these limestone skeletons. The animals that live in the coral are actually related to jellyfish and sea anemones and are called polyps. Each polyp plays host to a tiny one celled plant called a zooxanthellae, which is vital to the coral's survival. The coral build their own colonies, which are called coral reefs, some of which are thousands of years old.

Coral reefs provide shelter and protection for thousands of species of animals and plants.

Some crustaceans, e.g. crabs and shrimps spend most of their lives living in coral. Seven types of marine turtle live in the Great Barrier Reef alongside Dugongs, dolphins and tropical fish.

There are many threats that face the coral reefs and the animals that live in them. Many reefs are over fished and /or polluted. In the Great Barrier Reef prawn trawling kills almost ten times as many creatures than are actually eaten. Vast areas of sea floor are lost by destructive trawl gear, and every day marine turtles die trapped in fishing nets. Pollution disrupts essential parts of the reef's ecosystem as millions of tonnes of harmful sediment and chemicals pour into the sea, and every year more oil spills from even larger tankers devastate huge areas.

Threats to coral

Another problem concerns the so-called "precious coral" which does not form an external skeleton of limestone but an internal one, which enables it to grow delicate branches. This coral can be a huge variety of colours and is even prettier than the usual coral. However, some people think this wonderful coral is nicer polished on a mantelpiece as an ornament that live on the sea floor. The seabed is dredged in the Mediterranean Sea and off the coast of Japan to collect the precious coral for sale, and not only the coral is killed in this process.

Recently there has been a new problem for the reefs in the form of a murderous starfish, which has appeared in growing numbers, especially in the Great Barrier Reef. This starfish is called "The crown of thorns" which kills and eats growing polyps, the creatures that live in the coral. As the coral cannot recover, divers have been sent down to inject the starfish with poison but this was not effective. Other solutions have been suggested, but none are realistic. If these starfish are not killed, the reefs will die and slowly be worn away by the sea.

Some of the beautiful diversity of life in the coral reefs

However, the threat that I think is the most serious to these patches of ocean is global warming. Global warming is caused by the green house gases emitted by cars, power stations, factories and many more industrial machines. The gases rise to the atmosphere where they form a thick layer, which is mainly carbon dioxide. When the sun heats the earth, some heat normally goes back up into space, but now the layer of gas reflects most heat coming up and out so that it goes back down to the earth. This means that, as not much heat can escape, our planet is gradually overheating.

With the slight increase in temperature, although only a few degrees, the polyps in the coral become stressed and respond by expelling their tiny guests - the zooxanthellae. Then they lose their colour and die. This so-called "bleaching effect" happened in the Great Barrier Reef in 1998 - the same year had the highest ever recorded sea temperatures. In this major coral bleaching event some corals more than 1000 years old died, they will never be replaced unless the "crown of thorns" threat is removed.

I think that we should act now to save our coral reefs because if we do not, one of the most beautiful and life-teeming environments on this planet will be lost forever.

Where Next?

On ClimateX.org

Many scientists share Sarah's concerns about the threats to coral reefs. Peter Mumby from Newcastle University has written about the impact of climate change on reefs based on the results of more detailed monitoring. See the article ‘Coral Reefs Fading Fast'. For an even more personal lament read scientist Scott Henderson's account of what he has witnessed as a diver, ‘The Rainbow Unwoven'.

For another successful competition entry from a young science writer read ‘Energy of the Future and how it affects the Balance of Nature' by Emily Dennis.

External links

There are international and national organisations working to protect and manage coral reefs around the world. The Coral Reef Alliance (CORAL) (http://www.coral.org/), based in San Francisco, USA, is one such organisation; a member-supported, non-profit organization, dedicated to protecting the health of coral reefs by integrating ecosystem management, sustainable tourism, and community partnerships.