Ecology

Ecology is the science of living things, the environment and their interactions with each other. You can see this in action at Long Reef.

Intertidal zones, exposure to waves and patchy habitats

Intertidal rocky shores have a variety of habitats which are created by a combination of geology, exposure to waves and the slope of the shore. The type of habitat affects what animals and plants live there. Long Reef is a great example of a rocky shore that has a wide range of habitats and therefore a wide variety of animals and plants.

Geology

Softer rock, like sandstone, erodes easily. Over long periods of time rockpools, crevices, hollows, cracks and boulders form that become habitats for animals and plants to live.

Harder rock forms flat areas, large and small, where many animals feed during high tide and low tide.

Exposure to waves

Long Reef has areas exposed to large waves and also more sheltered areas.

Where medium to large waves hit the shore:

• seaweeds usually have large fronds (leaves) and a firm hold on the rocks (called holdfasts) to withstand the force of the waves.
• animals will be good at:
• holding on, such as those with a large foot eg limpets.
• finding shelter quickly eg crabs and octopuses.
• attaching premanently to the rock eg sea squirts and barnacles.

In sheltered areas where the waves are smaller:

• the seaweed form crusts that look like different coloured leathery rock. There are also leafy and stringy types of seaweed in rockpools and crevices that keep wet during low tide.
• there are lots of snails, small crabs and barnacles.

Slope of the seashore

The slope of a rocky shore creates zones based on the length of time the slope is covered by the tide. The higher up the slope the more time it’s out of water. These zones are called intertidal zones and they affect the types of animals and plants that live there. The area between high and low tide known as the littoral area, is usually split into three parts or zones – Upper, Middle & Lower.

The combination of geology, exposure to waves and slope of the shore create a patchwork of plants and animals. In the steep areas at Long Reef you can easily see the different zones. In other areas there are no strong zones but a mix of flat bare areas and patches of different animals and plants.

Different habitats

Long Reef has a wide range of exposed and sheltered habitats including:

Rockpools

Rockpools can be very shallow, from less than 5cm deep to being a 1m or more. They contain snails that graze on seaweed, carnivorous snails that eat other snails and barnacles, starfish, sea anemones, crabs, small fish and sometimes octopus. Long Reef has lots of different rock pools.

Neptune’s necklace

Neptune’s necklace (Hormosira banksii) is a brown seaweed that looks like a string of beads. They can form large beds in flat areas of the middle littoral zones that remain moist most of the time. They provide shelter for a large variety of snails and small crabs during low tide. There are large areas of Neptune’s necklace providing habitat at Long Reef.

Crevices and cracks

Crevices and cracks are gaps between slabs of rock which can occur anywhere on a rocky shore. The animals and plants found here vary depending on where they are on the shore. When the tide is out, animals may congregate in a crevice to retain moisture and then move away from the crevice when the tide is in. Long Reef’s rock platform has many crevices and cracks for animals to hide in.

Hollows

Hollows are curved depressions in rocks usually very low on the shore and exposed to waves. These are created by sea urchins gradually wearing away the rock with their spines as they cling to the rock while resting. Where many of these hollows occur together they are called ‘sea urchin apartments’. Sea urchins usually leave these hollows at night and graze on the surrounding flat rocks covered by the sea. Long Reef has a great example of sea urchin apartments.

Flat rocky areas

Flat rocky areas that exist between rockpools, crevices and boulders appear to have no seaweed. In fact they are covered with microalgae, tiny plants naked to the human eye. These plants are a vital source of food for many snails and starfish and these animals will crawl over the flat areas during mid-low tide and high tide or during rain to feed. Long Reef has large areas of flat rocky shore.

Boulders

Boulders are medium to large rocks that are heavy enough not to be moved by small to moderate waves. They are usually found in more sheltered areas. The underside of boulders house an enormous variety of animals and plants such as sponges, tube worms, colonial sea squirts, chitons, blue ring octopus, snails, barnacles and sea anemones. Some of these animals are not found in other habitats. Long Reef has an extensive boulder field.