Natural Ecosystems - Intertidal Rocky Shores
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| Life on the intertidal rocky shore is tough: the animals and plants must contend with storm waves, desiccation, extreme temperature changes, hypersaline conditions in evaporating rockpools, and predation. Seaweeds fringe the permanent rockpools, hiding the small crabs, seastars, and anemones below. On rocks covered by the tide for only part of the day, grazing snails, mussels and barnacles are the dominant animals. The uppermost part of the shore, receiving only the splash from the highest waves, is home to the hardiest of the intertidal organisms, such as tiny littorinid snails and lichens. A characteristic rocky shore community is present where rock is exposed at the shoreline. In Victoria this habitat occurs mainly on rocky headlands from Portland to Wilsons Promontory, with some minor occurrences in the far east. Although there are some differences in species between the warm temperate waters in the far east and the cool temperate waters of the central and west, the type of rock and the degree of exposure to the prevailing storm waves are especially important. |  |
Headlands sheltered within our larger bays will support suites of species that differ from those on sites battered by the waves arriving directly from the Southern Ocean. This difference is often reinforced by the characteristics of the underlying rock. The basalt along the oceanic side of the Mornington Peninsula weathers gracefully, allowing a multitude of creatures to hide under the loose rocks, or within the crevices and cracks that form. The granite around Wilsons Promontory is hard and impermeable, defying occupancy to all but the most tenacious animals and plants.
| The larger seaweeds that are found on Victoria’s intertidal rocky shores include Neptune’s Necklace and the large and fleshy Bull Kelp which grows on the lower fringe of more exposed rocky shores. Most animals on the intertidal rocky shores are herbivorous molluscs, grazing algae off rock surfaces. Filter-feeding organisms abound, including tube-building worms, sea squirts (cunjevoi), mussels and barnacles. Crabs and seastars, hermit crabs and shrimps scavenge in rock pools. Predators include snails, fish, and birds such as the Pacific Gull and Sooty Oystercatcher. The conservation of our rocky intertidal shores depends on the control of habitat destruction, illegal harvesting, pollution, and physical disturbance. Recreational collection of intertidal organisms was beginning to have such an impact that it is now prohibited along much of Victoria’s coast. Exploited species included warreners, abalone, elephant snails, dog winkles, limpets, top shells, crabs and cunjevoi: some of the once-common snails are now rarely seen. Rocky intertidal shores are protected within parks and reserves along the coast, although the extent and nature of the protection varies. Work is currently being undertaken to determine future shoreline reservation and protection needs. |  |