Global temperatures have already risen by about 1C since pre-industrial times. The UN has warned that if that rise reaches 1. Great Barrier Reef: Can tech help it survive? Great Barrier Reef suffers another mass bleaching. Great Barrier Reef outlook is 'very poor'. Uncovering the secrets of Australia's hidden reefs. Barrier Reef 'coral babies' in mass decline. Heatwaves 'cook' Barrier Reef corals. Dead or dying coral is 'bleached' of its colour. Great Barrier Reef suffers third mass bleaching Australia downgrades reef outlook to 'very poor'.
The loss of more complex coral structures means habitats for fish are also wiped out. Efforts to save the reef:. Can tech help the reef recover and survive? Soft corals grow relatively quickly and may double or triple the size of their colonies over a year. Some corals have pigments fluorescent proteins in their tissues that give them their orange, yellow, green, blue, red and purple colours.
Others get their golden-brown colour from the algae, called zooxanthallae, that live within their tissues. Most of their nutrients come from the zooxanthellae. Like plants, zooxanthellae use the sun to make food for themselves and the coral. This is why it is important for corals to live in clear, shallow waters where they can get lots of sunlight.
Corals also eat plankton — these are tiny animals or plants which drift around in the water. Some corals also consume very small fish. To catch these animals, the corals use their tentacles to paralyse their prey with specialised stinging cells called nematocysts. They can also feed on tiny plants or from the zooxanthellae that live within their cells. Home The Reef Corals. There are two main types of corals — hard and soft. Hard corals Hard corals act as building blocks for the Reef.
High water temperatures cause this relationship to break down; the zooxanthellae are expelled by their host corals, and the corals starve and turn white in the phenomenon known as bleaching.
The coral species illustrated here are all found in the outer reef at Heron Island, at about 1—3m depth, as well as in other shallow reef zones of the Great Barrier Reef. Most soft corals have limestone spicules that provide some structural support by slightly stiffening the soft tissues.
In organ pipe coral, the spicules fuse to create a hard skeleton of pipe-like tubes, with each single polyp bearing eight feathery tentacles. Colonies of organ pipe coral can occupy large patches of reef. Inhabits shallow waters down to about 12m. Flowerpot corals are made up of many individual polyps joined together at the base of their skeletons to form branches, columns or dome-shaped colonies.
The individual polyps are highly flexible and active, and constantly moving around and feeding. Their colonies can spread widely, growing many metres across. Found in upper reef slopes with low wave action, 5—25m deep. Common in shallow reef areas, particularly those that are exposed to strong wave action, although it can occur to a depth of about 15m. It is a hard, branching coral with blunt, slightly flattened ends. Colour ranges from cream, pink or blue to greens.
Common in shallow inner reefs, but also found less frequently on the outer reef. This small, stony coral grows in a rounded hump shape. It prefers to grow in the absence of other species, although it can occasionally be found near algae or other corals. It uses symbiotic algae to photosynthesise by day and filter feeds on plankton by night.
A stony, reef-building coral that grows in either hand-like or tree-like colonies, with blunt, upright branches. It is covered in very small corallites that give it a rough, sandpaper-like texture.
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