The Ningaloo Reef is over 260 kilometres long extending from Point Murat on the North West Cape to Amherst Point south of Coral Bay, this makes it one of the largest fringing reefs in the world.The reef crest lies as close as 100 metres off the coast in some places and at its furthermost point it is 4 kilometres off shore.

This reef is unique because it is one of only two coral reefs in the world that have formed on the western side of a continental land mass. Predominantly there are anti clockwise direction equatorial currents in the southern hemisphere. Usually these currents carry cold water up the western coast from the Antarctic and warm water down the eastern side of continents from the equator, however, in Western Australia the Leeuwin counter current carries a stream of warm water down the Western Australian coast. This enables reefs such as the Ningaloo, Abrolhos and Rottnest reefs to form and survive.

Living Coral Reefs are made up of thousands of tiny animals called coral polyps. These are basically a fleshy tube with a mouth that is surrounded by small tentacles. Most corals are nocturnal. At night the tentacles are extended to trap food that drifts past in the ocean currents. This is a colourful sight as the soft bodies are exposed to the human eye. The coral polyps also obtain nutrients from products produced by algae that live in their tentacles. For the algae to produce these products they must photosynthesise. Therefore coral reef needs warm clear water and plenty of sunlight.

Some coral polyps secrete a hard calcareous outer casing to protect their soft bodies, these types of coral are called hard corals and it is their outer casings that form the reef over time. There are however, also soft corals that do not produce a hard outer casing (or somewhere to retreat to in daylight). There are fewer species of soft corals in this reef area, they are generally white feather like or fern like structures on the larger lumps of hard coral and they sway in the ocean currents as they do not have the hard protective casing. For protection, many of the soft corals produce a substance to repel fish. The Hydrozoan (Fire Coral) in particular can cause a painful sting, even to humans.

On the Ningaloo Reef there are over 200 species of Hard Corals and approximately 50 species of Soft Corals.
Some of the most commonly seen on the reef are:

• The large flat Plate Coral
• The round bulbous Brain Coral
• The fingerlike Staghorn Coral
• The leaf like Cabbage Coral

These above corals are some of the faster growing.

Once a year many corals re-produce by mass spawning. This spawning takes 1-2 nights and occurs 8-9 days after the full moon in March/April. A similar mass spawning occurs on the reefs further south & north a couple of days before or after and in November on the Great Barrier Reef. Scientists remain unsure as to what actually causes the spawning at the same time each year.

The majority of corals are hermaphrodites, which means that they can produce both Male and Female eggs. During the spawning the corals release millions of sperm and eggs into the water over a few nights. This is usually pinkish/red in colour and has been known to form a reddish slick on the waters surface. Fertilisation of the eggs then occurs in the water 1 - 2 hours later. Once fertilised they change to Planuli through the process of cell division, this Planuli will then drift on the ocean currents for several days before they attach themselves to the sea floor and start to grow. Corals grow by budding and cloning new coral polyps. The rate of corals growth depends upon the species and the prevailing conditions such as the amount of food, the clarity of the water and the amount of sunlight they receive. On average each coral will grow between 4 - 5 mm per year and therefore it takes a long time for the reefs to form.

Fish graze on the coral, in fact they consume over 1/3 of the annual coral growth each year. The parrot fish has developed a beak so that it can scrape away the living coral polyps and their scraping marks are left clearly visible as white areas on the large lumps of coral.

There are numerous things that damage the reef:

• The Crown of Thorn Star Fish is found in large numbers on the Great Barrier Reef. We fortunately do not have these large numbers of Crown of Thorn on the Ningaloo Reef, it is however found here in natural proportions. The main threat to the Ningaloo Reef seems to be the Drupella Snail which feeds on the Hard Corals. This feeding snail leaves large areas of corals devastated. The only predators for this snail are a few of the reef fish such as Bluebone Gropers, Parrot Fish and North West Snapper.
• Cyclone and strong wave action can also cause severe coral damage. The last cyclone to pass through the Ningaloo area was said to have lifted large amounts of Plate Coral, this is clearly visible where a flattened path can be seen.
• Careless boat owners who anchor on the coral reefs also do extensive damage. Education is needed to advise people never to drop anchors on top of the coral reef area, instead it is advisable to look for sandy patches nearby.

There are some 500 species of fish on the Ningaloo Reef. Some of the most common smaller fish are the Parrot Fish, Butterfly Fish, Angel Fish, Damsel Fish, Scissor Tails & Wrasse. There are also many larger fish such as Groper, Coral Trout, Cod, Trevally, Mackerel and the occasional small Reef Shark. Many of the fish spend their entire lives in the one area of the reef as they are territorial. In particular the smaller tropical fish of the reef spend most of their life in the one location.

Turtles are common to this area and there are 3 known species who regularly frequent the beaches. The most common is the Green Turtle then there are the Loggerheads and Hawksbills. Between the months of October and April the Turtles mate close to shore. The females then come ashore to lay their eggs which are soft shelled and look like table tennis balls. During this time it is very important that the females are not disturbed. The sex of the hatchlings is determined by the temperature of the sand in which they are buried. Generally if the sand is warm the hatchlings will be predominately female.

The Exmouth area and the Ningaloo Reef are becoming increasingly important to the study of Humpback Whales. These animals can be seen migrating north to their breeding grounds on the North West Shelf. They can be seen in this area anytime between May and October each year. Other whales found in this area are - Pygmy Whales, Pilot Whales, Killer Whales and False Killer Whales. Whales are often seen close to shore and are also often seen in the shallow waters of the Exmouth Gulf.

Another common visitor to the Ningaloo Reef is the giant Manta Ray, these rays can be up to 4 metres across their wings. They are dark on their upper body and white underneath and are usually accompanied by Cobia which is a reasonably large fish.

The Ningaloo Reef is one of only a few places in the world where the giant Whale Shark regularly visits. Whale Sharks are large plankton feeding sharks that may grow to 18 metres in length. This shark is creating a lot of interest throughout the world and many people travel to Exmouth to snorkel with and observe these gentle giants. The Whale Sharks arrive in these waters in March and April each year. Not a lot is known about these sharks at this time, however studies are currently being undertaken.

To protect this unique resource, Ningaloo Marine Park was declared in 1987, encompassing about 224,000 ha of State controlled waters and approximately 700 km2 of Commonwealth waters. The Park extends from the northern end of Exmouth Gulf to Amherst Point, approximately 260 kms south of the North West Cape.

Ningaloo Marine Park is managed by the Department of Environment and Conservation in conjunction with the management of Cape Range National Park.

Links: www.naturebase.net (DEC)

For further enquiries contact:
Department of Environment and Conservation
PO Box 201, Exmouth WA 6707
Telephone: (08) 9947 8000 Facsimile: (08) 9947 8000
Email: exmouth@dec.wa.gov.au