Moreton Bay is geographically positioned between tropical and temperate waters. This, with its relatively shallow marine environment and large input of freshwater from its catchment, results in a complex and fragile ecosystem that is extremely productive. The Bay has an extremely diverse range of flora and fauna.
Apart from providing excellent habitat for different mangrove species, within the waters of Moreton Bay are salt marshes, coral reefs and large seagrass beds. Mangroves provide nurseries for fish, prawns and crabs and act as soil stabilisers, helping to reduce excessive sediment flow and decreasing the threat of erosion caused by currents and stream flow. Seagrasses are flowering plants, close biological relatives of lilies and orchids. Onshore, the Moreton Bay fig, a unique large tree endemic to shores and surrounds of Moreton Bay.
Moreton Bay is home to hundreds of species of fish, six of the world’s seven sea turtle species, three species of dolphin and herding dugong. It also contains numerous species of shark and ray and thousands of mollusc and other invertebrates.
Throughout the year, many different species of whale visit Moreton Bay. Humpback whale, Killer whale, Southern Right whale, Sperm whale, Melon-headed whale, Bryde's whale and, Minke whales are some of the species that can be seen in the Bay. Under Australia's Environment Protection and Biodiversity Conservation Act, the southern right whale is listed as endangered and the humpback whale is listed as vulnerable.
The Bay is a very important area for herding dugongs. It is one of three important sites in Queensland (along with the Gulf of Carpentaria and Torres Strait) where large numbers of dugongs habitat. Historical records have listed dugong herds numbered in the thousands, with some herds 5km (3 miles) long by 250m (820 feet) wide. Now there are fewer than 1,000 dugong in Moreton Bay.