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Introduction

Australia is the largest island continent, and controls the world’s third-largest area of ocean. Our marine jurisdiction extends from the shoreline of the estuaries, bays and beaches, out to the edge of the Exclusive Economic Zone (EEZ), about 200 M (nautical miles) from the coastline of the continent and the islands. This covers an area of about 9.1 million square kilometres, with about a further two million square kilometres in Australia’s Antarctic Territory). In addition to the EEZ, under the United Nations Convention on the Law of the Sea, Australia also claims control of an additional 3.4 million square kilometres of extended continental shelf in ten places around the mainland, the islands and Antarctica. So in total, Australia is responsible for a marine area of about 14.7 million square kilometres. This is greater than all the Australian land area combined—the mainland, islands and Antarctic Territory are about 13.6 million square kilometres.

The mainland EEZ has a coastline of about 36 000 kilometres, and spans more than 5000 kilometres from the tropics (9°S) to temperate latitudes (47°S). This extensive continuous coastline, together with about 12 000 islands from the tropics to the polar region, including a number of major oceanic offshore island groups (such as Cocos Keeling in the Indian Ocean, Lord Howe Island in the South Pacific and Macquarie Island in the Southern Ocean) creates a vast array of tropical to sub-Antarctic shallow water conditions and habitats. Together with the deepwater areas of the continental shelf and the slope, and the overlying water column, this complement of ocean and coastal systems provides Australia with a vast array of highly diverse marine habitats and ocean features.

These diverse ocean and coastal habitats are colonised by an equally vast biodiversity, which includes large proportions of endemic temperate species of flora and fauna, part of the tropical Indo-West Pacific world centre of species richness, extensive tropical–temperate transition areas, and large areas of Antarctic and sub-Antarctic territory and islands. As a result of the long history of geological separation, Australia’s location at the junction of three of the world’s major oceans, and the span from tropics to the Antarctic, Australia probably is the world’s most important single jurisdiction for marine biodiversity.

Australia is one of 12 nations who together are responsible for more than 70 per cent of the world’s biodiversity—known as ‘megadiverse’. It is known that that Australia is biologically rich, but much (and possibly most) of Australia’s marine biodiversity still remains to be discovered (see for example Ponder et al. 2002), especially the species of the outlying islands, continental shelves, shelf edge canyons, and the continental slopes and their overlying waters, all of which are difficult to sample and study. But even though there are many important species inhabiting Australian waters, for most of them we do not understand how their populations are maintained, or what environmental features are critical for their long-term survival. Despite this, the existing knowledge is sufficient to indicate that the marine biodiversity of Australia’s waters has outstanding and universal global importance, as is evident in virtually any group of marine plants or animals that have been studied well enough to be able to make an informed judgement.

Just some examples of the outstanding importance of our marine biodiversity are as follows:

• Australia has the highest number of species of mangroves  in the world—39 of the world’s 68 species (Spalding et al. 1997)
• Australia hosts 34 species of seagrasses  in the shallow tropical and temperate inshore waters (more than half of the world’s 60 species) and 11 of the world’s 12 genera of seagrasses (Short and Coles 2001), as well as the world’s largest seagrass bed (in Shark Bay in WA).

The temperate waters of Australia’s south-east region (NOO 2002) hold:

• the world’s highest levels of species richness and endemism (distribution restricted to the region) for marine flora—about 1200 species of marine macro-algae, which is about 20 per cent of the world’s species, with levels of endemism of about 70 per cent
• about 600 fish species with about 80 per cent endemism
• many hundreds of molluscs and echinoderm species, of which more than 90 per cent are endemic.

Although little explored, Australia’s deeper waters also appear to have high diversity and endemism when compared to similar systems elsewhere (for example, Richer de Forges et al. 2000).

Australia’s marine biodiversity is the basis for many important tourism and recreation activities, as well as commercial, recreational, traditional and subsistence fishing. The overall value of biodiversity in the world’s oceans is estimated to be about US $21 trillion per year (Costanza et al. 1997), and the value of Australia’s marine industry is around $22.4 billion (NOO 2001). While Australia’s fisheries are limited compared to some other countries (because of the generally low nutrient status of our oceans), they nonetheless provide for an important source of wealth and recreation in most coastal areas of Australia. The commercial fisheries are concentrated on high-value but low-tonnage benthic species and products. In 2003–04, Australia’s commercial fisheries (including aquaculture) produced about 267 000 tonnes of seafood  valued at about $2.2 billion (ABARE 2005). In addition, recreational and subsistence fisheries form an important part of Australia’s unique coastally-focused culture, and make a major contribution to the Australian way of life. This is reflected in the economic value of coastal recreation  and in the recreational catches  of fish, which, for some species, are now thought to be larger than those of the commercial catch.

Australia’s rich marine biodiversity also offers the prospect of new chemicals that may be active in fighting diseases that afflict modern society. About 80 per cent of the world’s population relies upon natural medicinal products. Of the top 150 prescription drugs used in the US, 118 originate from natural sources: 74 per cent from plants, 18 per cent from fungi, five per cent from bacteria, and three per cent from one vertebrate (a snake species) (Daily et al. 1997). Globally, there is considerable current interest in the potential for deep-sea bacteria to provide new bio-active molecules that may ultimately be developed as new pharmaceutical products. Bio-prospecting for such new compounds has become an important part of the effort to explore and better understand the diversity and natural function of Australia’s marine biodiversity.

The ocean has a major climatic influence on all coastal regions. Sea breezes and temperature moderation generated by the ocean environment make many otherwise less tolerable coastal areas highly liveable. The oceans are also dynamic, and their impacts on shorelines and coastal systems can be extreme at times, particularly during storms and cyclones. This variability is a dynamic feature of ocean and coastal environments, but the variability and rate of change are increasing as a result of global changes in climate. In particular, changes to the patterns in ocean currents are affecting coastal and ocean ecosystems, and beginning to affect the distribution of marine biodiversity. At the shoreline, changes in wave and current patterns are altering the shape of the beaches and dunes, and there are likely to be greater changes as extreme events (storms and cyclones) become more frequent and more intense.

The vastness and the remoteness of Australia’s oceans belies their vulnerability. Offshore and deepwater activities are increasing, and no longer is it appropriate simply to ignore remote areas of the ocean, or the deep waters, on the basis that they are too difficult to assess and manage, or that they are far from land and can look after themselves. Policy decisions about such matters as the amount of fishing effort permitted in an area, the zoning and management of coastal land, and management of the ballast water of ships, amongst many others, all have the potential to have a big effect on ocean ecosystems. But perhaps even more importantly, many of the pressures related to such policies can be cumulative, and they may interact with natural stresses and variability to have even more profound effects.

While there have been many programmes committed to reducing marine impacts and pressures, and despite all the best intentions of managing within a complex world, we may still be facing the decline of important assets and features of ocean and coastal ecosystems. To guard against this happening without our knowledge, it is necessary to rely on monitoring systems that can detect the most important changes and provide alerts to generate a suitable management response. Australia has, however, few systematic national integrated monitoring systems in place. For example, there are sites in some coastal locations where long-term monitoring of some features is conducted (such as on the Great Barrier Reef) but there are no systematic, long-term national programmes that monitor key features such as coral reefs, seagrasses, or water quality to provide information about their condition. So precious little is known about their condition, or their trends.

In the sections that follow, some of the important features of the oceans and coasts are discussed, and, although there are very little data or knowledge on most of them, the key issues and trends are highlighted. Where they are available, specific examples of trends in the condition of the ocean and coastal ecosystems and pressures upon them are also provided to illustrate what are presumed to be the more general trends in conditions, pressures and responses.

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