There Is More To The Great Barrier Reef Than Meets The Eye

When most of us think about the Reef, we typically visualise diverse corals, a magnitude of fish species and other marine life. But the Reef is much more. We should think of the Reef as a system that starts at the high tide mark along the coast and continues out to outer edge of the continental shelf, in some areas, this may be up to 250 km off the coast.

This system is all connected by what is often referred to as the Blue Highway. The overall health of the Reef is entirely dependent on the health and connectivity of the system.

A good place to start exploring the system is the intertidal area of our coastline where we find the Mangrove forests. Mangroves play a vital role in the Reef system; protecting coastlines, filtering nutrients and trapping phytoplankton. They supply food, provide shelter and act as nurseries and breeding grounds for many fish and crustacean species. For example, baby snapper like the Mangrove Jack grows up in the tropical rivers and mangrove estuaries and then migrate 10’s of kilometres offshore to the coral reefs to spend their adult years.

Mangroves are an important ally in the fight against climate change as they absorb up to five times more carbon from the atmosphere than other trees.

Moving just offshore from the Mangroves, we find the all-important seagrass meadows. Seagrasses are underwater flowering plants that grow in the shallow intertidal area, and similarly to mangroves, they stabilise the seafloor preventing erosion. Seagrasses are also great sequesters of carbon. Seagrass beds are nursery grounds for juvenile fish and prawns, some of which play a vital role in our commercial fishing industries.

Highly productive seagrass beds also provide food for sea turtles and dugongs. The dugong is the world's only completely herbivorous marine mammal and are almost entirely dependent on seagrass. No seagrass, no dugong.

As we move away from the intertidal and out towards the coral reefs, we would encounter a seafloor that was once thought to be barren but is now seen as an important connection between inshore habitat and offshore habitat. The seafloor is covered with small coral outcrops known as isolates and inter-reef gardens of soft corals. These act as roadhouses for the many fish that move between the coral reefs and the intertidal.

Continuing seaward, we finally reach the great coral reef formations that give the Great Barrier Reef its name. Coral reefs are some of the most diverse habitats on the planet.

But now we understand that the connections to surrounding habitats, from the mangrove forests to the seagrass meadows to the isolates and inter-reef gardens has created and supports one of the richest and most complex natural ecosystems on earth, the Great Barrier Reef.

Contributed with thanks to Whitsunday Conservation Council.

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The Great Barrier Reef from Space. Photo supplied.

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