Intertidal Reefs

Intertidal reefs are the rocky areas of the coastline extending up to the high tide mark. There is a wide range of intertidal habitats, each of which is divided into separate zones based on the influence of the tide.

It is illegal to remove any benthic (bottom dwelling) organisms from any intertidal rocky reef in South Australia from high water mark out to a water depth of two metres.

Intertidal animals include barnacles, shrimps, snails, crabs, coral, abalone, periwinkles, limpets, worms and mussels. They are wholly dependent on the sea for their means of survival.

Barnacles and tubeworms feed when they are submerged at high tide, filtering microscopic organisms or particles of organic matter. Herbivores, such as limpets and periwinkles, browse on seaweed and other plants. Carnivores, such as larger molluscs (for example whelks) and crabs, hunt and scavenge for their food.

Intertidal organisms are also dependent on the sea for their reproduction. These organisms must shed their eggs or larvae into the sea, where the larvae may drift around in the ocean currents for weeks or months as plankton before they finally settle down to grow into adults, whether free-living or attached to hard surfaces such as rocks.

The removal of barnacles, shrimps, snails, crabs, coral, abalone, periwinkles, limpets, worms, mussels and other bottom dwelling organisms may see harmless, but it represents a loss of food for other species further up the food chain – including many highly sought after fish species.

Once removed, it is difficult for reef life to recover because their larvae cannot travel long distances to replenish depleted populations.

For more information about the protection of Intertidal reefs, download the brochure or contact your local Fisheries Office and ask for a copy to be sent to you.

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