Shell Beach is not your common sand beach - it's a beach made of trillions of tiny shells, all from one type of animal.

WA’s shell beach is a 110km stretch of the Coral Coast made almost entirely of cockle shells, between 7-10m deep. L’Haridon Bight in Shark Bay is home to billions of tiny coquina bivalve shells. This shallow, hypersaline (∼ 60‰), benthic marine environment, is dominated by the cockle Fragum erugatum (Mollusca, Bivalvia, Cardiidae). The proliferation of this particular species has resulted from the high water salinity (salt concentration) in this area, the tolerance levels of this cockle and no natural predation.

Photo by Manuel Caminero, 2013.

The characteristic rounded shells of cockles are bilaterally symmetrical, and are heart-shaped when viewed from the side with numerous radial ribs. There are more than 200 living species of cockles, with many more fossil forms. Cockles are a synchronous hermaphrodite which typically burrow using their ‘foot’ (a protruding aperture of their mantle), and feed by siphoning and filtering plankton from the surrounding water.

Similar to its close relatives the giant clams (Tridacnidae), Fragum erugatum possesses symbiotic zooxanthellae, which may facilitate survival in the hyperosmotic environment of Shark Bay. The association facilitates a large population size (but short life expectancy), allowing it to dominate a unique, hypersaline, oligotrophic environment.

Shark Bay World Heritage Discovery & Visitor Centre

Although shells are washed ashore continuously, large-scale deposition of the accumulated infratidal coquinas, largely composed these cockle shells, occurs periodically in major storm events. Shell beach has provided a long-term tropical cyclone record from the Indian Ocean region. Multiple shore-parallel ridges record a tropical cyclone history, which are responsible for deposition of the ridges.

First depositions were thought to have occurred here about 4000-6000 years ago. Over time, the shell deposits have cemented to form soft coquina limestone which is being utilised at the local coquinite quarry.

Shark Bay World Heritage Discovery & Visitor Centre

It is 1 of only 2 beaches in the whole world that is completely made up of shells! Pretty extraordinary if you ask me! The effect is brilliant; a long, snow-white beach bordered by aqua blue ocean waters. This little bivalve has created a spectacular feature of Western Australia’s Coral Coast.

Bibliography:

Berry, P.F. & Playford, P.E. (1997) Biology of modern (Mollusca, Bivalvia, Cardiidae) in relation to deposition of the Hamelin Coquina, Shark Bay, Western Australia, Marine & Freshwater Research 48( 5), 415-420.

Morton, B. (2000) The biology and functional morphology of Fragum erugatum (Bivalvia: Cardiidae) from Shark Bay, Western Australia: the significance of its relationship with entrained zooxanthellae, Journal of Zoology 251(1), 39-52.

Nott, J. (2011) A 6000 year tropical cyclone record from Western Australia, Quaternary Science Reviews 30(5), 713-722.

Chicks on the beach!

Sea Birds, Ningaloo Station (2003) Rhondas Photography Blog.

The birdlife that inhabit the West-Australian Coral Coast are integral and remarkable members of the “Coral Coast Crew”. This dynamic environment provides a range of habitat niches in which many bird species have evolved to fill.

The Coral Coast Crew includes such birdlife:

·         Oceanic wanderers, such as albatrosses, gannets and shearwaters that live a highly pelagic lifestyle.

·         Veritable Seabirds – including storm-petrels, cormorants, curlews, gannets and boobies, gulls and terns.

·         The occasional lost penguin stops in for a rest.

·         Shorebirds are those that take advantage of the inter-tidal zone, such as sand-pipers and oyster-catchers.

·         White-bellied sea eagles, ospreys and brahminy kites are the dominant birds-of-prey that rule the coastal skies.

·         The wedge-tailed eagle, Australia's largest living bird of prey, patrols the outback skies.

·         Emus, one of two Australia’s large flightless ratites, can be spotted running through the outback bush.

·         The cheeky laugh of the kookaburra and chortle of the magpie can be heard in treed areas of the southern Coral Coast.

·         Small bush birds are found throughout the region, including wrens and sparrows nesting in the limestone cliff edges.

(Slater et al. 2009)

The Coral Coast of Western Australia is home to more than 240 varieties of birds, with populations representing over 35% of Australia’s bird species (Slater et al. 2009). 

Birds that have adapted to life within the marine environment are known as seabirds (also known as marine birds). Modern seabird families emerged in the Paleogene period, while the first seabirds evolved in the Cretaceous (Slater et al. 2009).

Large breeding colonies of seabirds congregate along the coast and islands. More than 90 species of seabird have been identified on the Abrolhos Islands of Western Australia Coral Coast alone (Slater et al. 2009).

While they may differ greatly in physiology, behaviour and lifestyle, they often exhibit remarkable convergent evolution, as the same selective pressures, environmental issues and feeding niches have resulted in analogous (similar) adaptations.

Wedge-tailed Eagle, Coral Bay. - Bec Towers 2007

Terns in flight, Montebello Islands. – Dr. Andy Lewis (2014).

Sooty terns, Beacon Island, Wallabi group, Abrolhos. – Dr. Andy Lewis (2014).

Cormorants, gulls and terns in the foreground of MV TrueNorth at the Abrolhos Islands. – Dr. Andy Lewis (2014).

Pacific Gull, Rat Island, Abrolhos. – Dr. Andy Lewis (2014).

Osprey, Rat Island, Abrolhos. – Dr. Andy Lewis (2014).

Reference:

Slater, P., Slater, P. & Slater R. (2009) The Slater Field Guide to Australian Birds, 2nd edn., New Holland Publishers (Aus) Pty Ltd.

images:

Sea Birds, Ningaloo Station (2003) Rhondas Photography Blog, Bird Life Photography 2013, viewed 22 March 2014 <http://www.australianoffroad.com.au/_blog/rhondas-photography-blog/post/bird-life-photography/>

The Heart of Ningaloo Reef

Located on the stunning shores of Western Australia’s Coral Coast, Coral Bay is at the heart of the Ningaloo Reef and is home to a huge variety of marine wildlife 

- the "Coral Coast Crew". 

Watch:

Coral Bay, The Heart of Ningaloo Preview - by Migration Media 

This is a preview of Migration Media's Production “Coral Bay, The Heart of Ningaloo”, a compilation of underwater marine life footage and spectacular scenes of the Coral Coast, filmed by my friends in the bay. This video showcases some of the beauty of Ningaloo Reef and presents some of the unique animals that reside in and frequent these waters, including: Whale Sharks, Manta Rays, Dugongs, Turtles, Reef Fish, beautiful Coral Reefs and various types of Sharks and Rays.

Photo: Dancing with Manta Rays, Coral Bay - Cochise Page

Coral reefs are primary producers that sustain many trophic levels of ecosystems. The proximity of the reef to the continental shelf sanctions for oceanic current convergence of cold and warm waters (Sleeman et al. 2007). This creates upwelling and provides the necessary biophysical conditions to support a diverse array of species (Sleeman et al. 2007). The Ningaloo Reef hosts a large suite of resident marine megafauna including dugongs, sharks, dolphins and manta rays (Preen et al. 1997). Some marine megafauna such as humpback (Megaptera novaeangliae) and pygmy blue whales (Balaenoptera musculus brevicauda) migrate through Ningaloo Reef, stopping for a rest and a play, en route to breeding grounds further north (Sleeman et al. 2007). Turtles migrate to Ningaloo Reef to forage and nest (Preen et al.1997), while other migratory megafauna such as whale sharks (Rhincodon typus) have predictable seasonal occurrences at Ningaloo Reef to feed, and possibly for other reasons that are not yet clearly understood (Sleeman et al. 2007). Killer whales (Orcinus orca) are known to target krill feeders such as baleen whales as calves or juveniles, when in their high latitude breeding grounds. The trophic distributions and foraging of many marine megafauna species are often correlated with the physical and biological properties of surface waters, and ultimately on the primary productivity of the coral reef ecosystem (Sleeman et al. 2007).

Photo: Oyster Bridge, Coral Bay, Ningaloo Reef - Bec Towers

Here is another short video featuring “Coral Coast Crew” and highlighting the beauty and the importance of conservation of Ningaloo Reef. This part of the Coral Coast has an abundance of marine life, including endangered animals such as dugongs and whale sharks that live in Ningaloo and surrounding waters.   

Protect Ningaloo Reef

from Migration Media

References:

Preen, A. R., Marsh, H., Lawler, I. R., Prince, R. I. T., & Shepherd, R. (1997) Distribution and abundance of dugongs, turtles, dolphins and other megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia, Wildlife Research 24, 185–208.

Sleeman, J., Meekan, M., Wilson, S., Jenner, C., Jenner, M., Boggs, G., Steinberg, C. & Bradshaw, C. (2007) "Biophysical correlates of relative abundances of marine megafauna at Ningaloo Reef, Western Australia", Marine & Freshwater Research, 58 (7), 608-623.  

The Coral Coast boasts the Ningaloo Reef

  Western Australia boasts the dynamic and diverse ‘Coral Coast’ from Cervantes to Exmouth. Located within the Coral Coast, the world-famous Ningaloo Marine Park is regarded as one of the only remaining pristine ocean paradises on Earth. Extending along 300km of coastline, the Ningaloo Reef (NR) has evolved to be the only extensive coral system worldwide, to fringe the western coast of a continent.  This extensive and biodynamic ecosystem has a relatively short history, on an evolutionary time-scale, of only seven to eight thousand years as its corals have strong Indo-Pacific affinities. The NR has a narrow sandy lagoon, backed by an arid coastal plain, as it lies close to the Northwest Cape and the Cape Range anticline to the west of Exmouth Gulf. Australia’s largest fringing reef is influenced by climatic aridity, cyclones, strong oceanic swells across a narrow continental shelf, ocean current upwellings, and the poleward flowing Leeuwin Current. This current is a particularly important element in the eventual formation and colonisation of the NR. It is a unique tropical current that has played a major part in the evolution of the Coral Coast’s major marine ecosystem. Year-round exposure to high energy conditions affects coral growth and reef structure, as well as influencing the diverse array of organisms that inhabit these Coral Coast waters. This blog will explore some of the evolutionary biology behind the “Coral Coast Crew”. 

                                                 image: Australian Marine Conservation Society, 2014

References:

Collins, L.B., Zhu, Z.R., Wyrwoll, K. & Eisenhauer, A. (2003) Late Quaternary structure and development      of the northern Ningaloo Reef, Australia, Sedimentary Geology, 159 (1), 81-94.

Australian Marine Conservation Society, 9 March 2014, Australian Marine Conservation Society,          <www.marineconservation.org.au/pages/northern-territ-north-west-marine-region-96.html>