The Great Barrier Reef

The Great Barrier Reef stretches

along the coast of Queensland for

more than 3000km and is home to

thousands of different species of

organisms.

Algae and Seagrasses

Algae are a diverse group of autotrophic organisms that inhabit both the sea bed and upper

levels of the ocean. Seaweeds, Seagrasses and Phytoplankton are the primary producers in

the Great Barrier Reef. Seaweeds are the food source of many species of fish including the

Parrot Fish and Surgeonfish (Dory from Finding Nemo). On the other hand, Green Turtles

and Dugongs prefer to graze on a variety of Seagrasses. Phytoplankton are photosynthetic

bacteria that live in the well-lit surface region of the ocean. Phytoplankton are a crucial part

of the marine ecosystem because they are fed on by Krill (tiny shrimp like creatures) which

in turn are the food source for larger organisms like the Humpback whale and many fish

species such as Lionfish and Clown Triggerfish.

Coral

Corals are marine animals that form compact colonies. When large numbers of these

colonies group together they create a physical framework that supports the development of

entire reefs, built upon the coral. Many of the corals that make up the Great Barrier Reef

produce their own energy and nutrients by working together with some photosynthetic

bacteria called Zooxanthellae that live within the coral. The coral and Zooxanthellae have a

very sensitive relationship, if water temperatures get too high the bacteria can be expelled

from the coral which can lead to the coral dying, this is known as coral bleaching

Molluscs and Shellfish

Molluscs are abroad group of invertebrates (animals

without a backbone) that include animals like Sea Snails,

Sea Slugs and Clams. Sea slugs commonly feed on

microscopic algae like phytoplankton. Sea slugs themselves

are slow moving and make for easy prey for some crabs.

Fish

Over 1500 species of fish inhabit the Great Barrier Reef,

ranging from small Bait fish that feed on Krill, to Tuna that

feed on Bait fish, right up to apex predators like the Tiger

shark. Tiger sharks can reach lengths of up 5m and are

opportunistic predators that have a reputation for eating

nearly anything including molluscs, small & large fish

(Tuna, Lion fish Surgeon fish, Parrot fish), Dugongs, Green Sea Turtles and even Dolphins

and Birds.

1: Create a food web using the information provided above on an A4 piece of paper (landscape). Hint: Start with the producers at the bottom of the page and work your way up through the different levels (primary, secondary etc.)

2: Predict 3 effects that could result from the Humpback whale being hunted extinction.

3: If the Krill population was infected by a deadly virus what might happen? Predict how this might affect 3 different populations of organisms.