Environment and Resource Management

Marine biodiversity

Biodiversity, or biological diversity, is the whole, interacting variety of life on Earth, the natural wealth of the world.

Biodiversity refers to all the different plants, animals and micro-organisms, the genes they contain and the ecosystems of which they form a part. Biodiversity is a constantly changing, even frantic, dance of life. It is increased by new genetic variation as species evolve. It is reduced by habitat degradation and extinction.

Biodiversity is the product of and, in turn, the provider of life on Earth. It supports human survival, providing us with food, fresh air, clean water and numerous services such as climate regulation, pollutant breakdown and absorption of carbon dioxide.

As the world's largest island, Australia has a great marine biodiversity, that is, a wide variety of life in its fringing oceans and seas. Queensland's marine biodiversity is extremely valuable, for economic and social reasons.

Yet we still know so little about the diversity of life on Earth. An estimated 90 percent of all living species are still unknown to science. The remaining species provide us with the resources and the recreational opportunities we need. That means our biodiversity is coming under increasing pressure. We need to protect this valuable resource; every Queenslander can do their bit.

Australia's marine biodiversity

Australia, the world's largest island, has a perimeter of about 36 000km. The coast and marine environments range from the tropical north to temperate southern zones.

The boundary of the exclusive economic zone is 200 nautical miles from the coast so our marine environment covers about 9 million square kilometres of oceans and seas.

Many habitats occur around the coastline.Rocky shores, sandy beaches, algal reefs and kelp forests dominate the cooler, temperate south. Coral reefs, bays, estuaries, mangroves and tropical saltmarshes dominate the north.

Australia has some of the most diverse, unique and spectacular marine life in the world. It has the largest area of coral reefs, the highest mangrove species diversity, the highest diversity of marine macroalgae and the highest diversity of temperate seagrass in the world. It also has the highest levels of biodiversity for some marine invertebrates (animals without backbones) such as nudibranchs. All major groups of marine organisms are present in Australian waters, and many are endemic or unique to Australia.

Queensland's marine biodiversity

Queensland has about 6000km of mainland coastline and a wide variety of marine environments. It has wetlands, mangroves and complex forest communities, and extensive areas of reefs extending to the edge of the continental shelf. Over half the state's coastline has rocky, sandy and muddy seashores providing relatively small, but rich habitats for marine species. Thousands of islands, formed of coral or sand, or of continental origin (for example, old volcanic) form many different habitats.

The biodiversity of these marine environments is affected by several major factors including climate, nutrient levels, and wave impact.

Tropical and subtropical temperature zones cover the oceans off Queensland. The El Niño event and the Southern Oscillation also affect Queensland's climate.

Queensland (and Australian) waters are low in nutrients. Because the surrounding tropical water masses are low in nutrients, there is little nutrient-rich deep water in the region and our ancient, leached soils provide few nutrients in run-off from land. Therefore our coastal waters have relatively low biology productivity. However, mangrove, seagrass and coral communities which are adapted to low-nutrient waters manage to be highly productive.

Varying impacts from waves also make a difference. In the north, wave energy is generally low. Tropical cyclones can bring high wind, higher waves and flood rains in summer. In southern Queensland, larger waves move onto the unprotected coast so beaches and dunes are far more common.

The effect of the different combination of these factors along the coast has produced areas of unique character.

The Queensland coast can be considered as 14 bioregions:

Three regions cover the Gulf of Carpentaria and west Cape York. The main vegetation is mangrove forest, with some extensive saltmarsh flats. Coral reefs are found around the islands, but the regions are best known for their crocodile and dugong habitats and the Peninsula's wetlands.

To the north lies the Torres Strait bioregion, which has extensive shoals, banks and up to 27 species of mangroves. This is a region of inter-mixing, where waters from Papua New Guinea and the Coral Sea combine, so there are strong currents. There are also numerous coral reefs.

Coral also dominates the east region of Cape York Peninsula and the Ribbons area which lies off shore. Inshore lies numerous mangrove forests and lagoonal reefs, with complex dense forests. Ribbon and detached reefs extend east to the edge of the continental shelf.

As we move further south to the Wet Tropical Coast, rainfall increases, mangroves and saltmarshes form major wetlands. Corals extend to the Central Reef area which lies off shore. The Lucinda-Mackay bioregion includes the Whitsunday and Cumberland Island Groups, numerous islands with fringing reefs and dense forests and wetlands.

Further out lies the Pompey-Swains region, formed by offshore reefs and large lagoons. This area of coral extends into the Mackay-Capricorn region, which extends south to Lady Elliott Island. Again, there are coral cays surrounded by lagoons with submerged reefs. Close inshore lies the Shoalwater Coast region with large coastal islands often covered in forests. A very large tidal range and rivers mean there are fewer corals.

The southern-most region Moreton region features extensive sandy beaches between rocky headlands and offshore sand barrier islands such as Moreton and Stradbroke. There are significant seagrass beds and more algae and less coral, but these support a wide range of tropical, sub tropical and temperate fish and other marine species.

The Biogeographic regions of Queensland (PDF, 18K)*

The value of marine biodiversity for Queensland

The sea has great economic value for Queensland. Coastal and marine tourism, fisheries (including prawns), and marine transport, all bring in millions of dollars every year. Marine biodiversity is also important for indigenous people.

Coastal Aboriginal people have been users and custodians of Queensland's marine environment for thousands of years. Dugong and turtles have been hunted as a food source and for cultural purposes. Dolphins were used to assist in fishing in Moreton Bay. Many fruits and nuts from coastal plants formed a major part of Aboriginal diets.

Pressures on preserving our marine biodiversity

As most Queenslanders live close to the sea, our lifestyle affects the biodiversity on which we depend. Clearing mangroves and wetlands for canal estates, airports, harbour development and urban development has reduced our wetland cover. The discharge of stormwater from gutters and of sewage (usually treated but still rich in nutrients) has adversely affected wetlands and in some places coral reefs. Discharges from industry, boats, and run-off from farms all affect water quality and increase the amount of mud and sediment. In turn, the species which depend on clean water are affected. Overuse of certain species also affects biodiversity, and some reef fish and prawns in the Moreton Region show declining catches and size.

An obstacle preventing wiser use is our lack of knowledge about many of Queensland's ocean environments. We tend to only know about marine bioregions we experience directly or through the media. For example, many of us know the pleasure of fishing in a quiet mangrove waterway and are aware of the value of such areas. Most of us have seen television programs on the Great Barrier Reef and appreciate its beauty and significance.

But other marine environments are not so familiar to us; some are still poorly known to scientists. This applies particularly to areas that are remote or difficult to get to including the Gulf of Carpentaria coasts or the deep water areas between the reefs off the east coast.

Because we tend to study the areas we can use, we know more about the places where there's good fishing or which are important nurseries for juvenile fish (like mangroves).

How can we protect marine biodiversity?

Species extinctions in the marine environment are infrequent and local extinctions are more common. It is easier to manage and control the use of communities of species rather than individual species. So all mangroves and seagrasses are protected by law. Large and obvious species like sea turtles, dugong, whales and dolphins are protected by law. Indigenous communities might have special traditional hunting permits to take a limited catch of dugong and turtles every year.

Biodiversity is also the subject of a national strategy and is protected to some extent under international laws which prevent, for example, the dumping of oils or plastics into the sea. World Heritage conventions require us to care for the Great Barrier Reef World Heritage area. International conventions about bird migration and the preservation of wetlands also require Australia and the states involved to take positive action to preserve crucial habitats.

We need to know more about our species too. Research projects are continuing but take time and money. That is why it is important to create marine reserves or parks to protect all species.

The department wants to conserve representative samples of each type of marine habitat. But first it has to identify all the habitats and then plan how to protect them.

This is proving an enormous task because of the variation around the coast. So the department has been classifying the marine systems, grouping areas that are alike. A series of reserve systems representing all marine habitat types is being established in Queensland to conserve our marine biodiversity.

However, some areas including the Gulf of Carpentaria are still not represented in marine parks. The proposed state marine park off eastern Cape York Peninsula will protect many of the unique habitats there.

You can do your bit

Each person living in Queensland can play their part by avoiding practices which damage habitats, by not polluting, by taking only the marine species they need for one meal, by increasing our awareness of species in the areas we use, and by reporting malpractices and the sightings of unusual species.

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Last updated 28 November 2003

Biodiversity

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