The University of Sydney has counted 10,685 beaches in Australia. About 65% of the Australian coastline is beach and most of us live near one or two. There are no privately-owned beaches in Australia, with the Crown owning land generally up to the high tide mark. Each beach has its own mix of grain size and exposure presenting different challenges for each species of beach animal.
Sources, Graham Edgar, activeinparks.org
Australia’s top 10 beaches (according to Brad Farmer)
1. Cossies Beach, Cocos (Keeling) Islands, Indian Ocean
2. Nudey Beach, Fitzroy Island, QLD
3. Moonee Beach, Coffs Coast, NSW
4. Turquoise Bay, Coral Coast, WA
5. Burleigh Heads, Gold Coast, QLD
6. Maslin Beach, Adelaide, SA
7. Dolly Beach, Christmas Island, Indian Ocean
8. Shelly Beach, Nambucca Coast, NSW
9. Boat Harbour Beach, North West Coast, TAS
10.Apollo Bay, Great Ocean Road, VIC
Beach Sand on the Move
Beach sand grains consist of mostly Quartz granules eroded from the rocky coastline or washed down rivers, mixed with the remains of broken shells. They can be transported over long distances before accumulating behind the shelter of a headland and forming a beach, or is the slow points of a channel where it will make a sand bank or cay. The beach sands on the Coast of South East Queensland originates in the NSW highlands and is transported North by the prevailing winds as far as Fraser Island.
Beach sand is pushed ashore and dries, either to be washed out to sea again, or driven further inland, especially the lighter grains. They build up in summer and autumn and are then often eroded by large storms that coincide with high tide. Some beaches build up massive backing dune systems like at Musselroe Bay (Tas), Shelburne Bay (Qld) or the desert at Eyre in South Australia. Rising sea levels can isolate these dunes as islands, such as Fraser Island and Stradbroke Island in Queensland.
These dunes may be stabilised by hardy plants like spinifex, or even move inland to swallow up adjoining forests. Less mobile dunes are colonised by shrubs, that fertilise the sand with fallen leaves until large stands of coastal heath and even eucalypt forest colonised the dunes. For soil that is so harsh and poor it is amazing that most coastal scrubland is alive with flowers and nectar eating birds. Regrettably much of our coastal heath has been cleared for development and agriculture, or has been burned out in frequent fires. Even trampling of small sections of vegetation can cause large sand blows that undermine the dunes.
Apart from swimming, surfing and sunburn, beaches also offer fun for the curious and observant. Beachcombers will spot many unusual creatures washed ashore. Some of the most interesting are those that come ashore after offshore planktonic blooms are trapped inshore by a change in the wind. These include violet snails, by the wind sailors, a multitude of different kinds of jellyfish. There are also a variety of shells, as well as fragments of sponge and sea squirts. As far as marine life goes it can seem like a particularly barren desert with the most visible things being dead seaweed and shells along the high tide line.
Anything living on a beach can look forward to being dried out and the wetted, buried and re buried by the tide and waves. A wave can disturb the sand on the seabed by as much as 40% of its height, a one metre wave can turn over 40 cms of sand. In the tropical North, large tidal ranges and frequent cyclones keep some areas of sandy shallows regularly turned over and often devoid of any bottom dwelling marine life. Hardy animals have evolved to cope with the tough conditions, but they are generally small and buried out of sight. They burrow down to avoid the wave energy but not too far as many beaches are oxygen poor at depth. These conditions tend to favour smaller animals like crustaceans and molluscs. Shellfish have a siphon to breathe with and can bury themselves quickly if exposed by the swell. Larger animals like ghost crabs stay buried during the day away from the burning sun. They emerge at night to feed. The food on beaches is provided by microscopic algae and plankton and by drift seaweed that washes ashore on the high tide.
The water in the surf line is surprisingly poorly circulated despite all the wave energy. Plankton washed inshore is trapped in surf cells where if gets pushed ashore, then sucked out by rips, to be washed in again. This creates suitable conditions for algal blooms and they can be seen as a light green line of scum on the beach. If nutrients are added from a creek or storm water outfall, then fine red algae can stain the water. Bacteria also coats the sand grains in the upper layers and becomes food for other small creatures.
Seaweed fragments can come ashore in huge banks after a storm. During the day it is eaten by kelp flies and at night swarms of isopods will emerge to devour it. Mostly the size of a couple of rice grains, they are so numerous they can strip a stranded fish carcass in a single night. Other species head out into the water to feed on the seaweed caught in the surge cells. These small animals are a bonanza for fish who dart in amongst the waves to feed in the shallows. This is an important food source of the juvenile stages of fish like whiting and herring.
Shorebirds In the higher and drier areas shorebirds often nest, particularly birds that can exploit the vast quantities of isopods, kelp flies and shellfish, like Hooded Plovers and Oystercatchers. Our culture is so fixated with beaches that very few of them are today truly wild any more. Some exceptions are the west coast beaches of Tasmania, and the beaches in our more remote tropical North. Here bird life is largely undisturbed by humans and their cars and dogs. Disturbance of nesting sites has become a significant threat to the survival of these birds. Even the kindest dog will cause birds to abandon nests, or disturb birds while they are trying to feed at critical phases of the tide. Keep your dog down on the wet sand on a lead, at designated dog walking beaches. These days many beaches have signs alerting beach users to bird breeding times, please follow the recommendations on those signs.
A lot of our beaches are also dirty, marred by rafts of plastic debris that washes ashore from nearby cities, or from offshore fishing boats. It is estimated that 600,000 plastic bottles enter the sea every day. Rope and fishing line easily tangles wildlife. The items are often old plastics that have deteriorated into tiny balls called micro plastics. They are easily ingested, especially by seabirds and they can kill.