The condition of Australian estuaries and bays, and coastal freshwater lakes and lagoons is covered in detail in the Coasts report. The Marine environment report provides a detailed assessment of the state and trends of marine organisms. We provide a high-level summary here.
Three coastal or marine ecosystems were listed as threatened ecological communities under the EPBC Act during the past 5 years:
- the Giant Kelp Marine Forests of South East Australia (2012) and Posidonia australis seagrass meadows of the Manning–Hawkesbury ecoregion (2015) were listed as endangered
- Subtropical and Temperate Coastal Saltmarsh (2013) was listed as vulnerable.
The primary threats affecting the Giant Kelp Marine Forests are the increase in sea surface temperatures associated with the southwards penetration of the East Australian Current, and the corresponding range expansion of kelp-grazing sea urchins. The cumulative consequences of coastal development (e.g. clearing and human-induced habitat modification), and invasive species, are considered key threats to the P. australis seagrass meadows and the Subtropical and Temperate Coastal Saltmarsh communities.
A range of habitats and communities—from the nearshore to the abyss, and from the seabed to the water column—were assessed for their current state and recent trends in the Marine environment report Most were in good condition, and trends ranged from stable to improving, where they could be assessed. However, the condition of canyons, seamounts and coral reefs ranged from good to poor, depending on the specific geographic region. For example, severe storms, bleaching and crown-of-thorns starfish have affected eastern reefs, whereas many regions in the north-west have been affected by bleaching. Habitats and communities in the Great Barrier Reef to the end of 2015 are considered to range from poor and worsening condition (corals) to good and stable condition (macroalgae, offshore banks and shoals) (GBRMPA 2014). The ecosystem encompassing ‘Fringing reefs—temperate rocky reefs’ was classed as poor and worsening; warm-water events and overgrazing by sea urchins are negatively affecting some temperate reef habitats. Trends were generally noted to be associated with limited confidence for many habitats.
Most species groups assessed are regarded as being in good condition overall, although information is lacking to assess the condition or trend of some invertebrate groups. Trends are stable or improving for most fish species, except inner shelf reef species, which are in poor condition and worsening, similar to temperate rocky reef and coral reef habitats.
In addition, some species:
- have improved from past declines (e.g. long-nosed fur seals—Arctocephalus forsteri, southern Great Barrier Reef green turtles—Chelonia mydas, humpback whales—Megaptera novaeangliae, orange roughy—Hoplostethus atlanticus)
- are stable (e.g. mesopelagic and epipelagic fish species, shy albatross—Thalassarche cauta)
- have declined as a result of cumulative impacts associated with high fishing mortality, bycatch within fisheries and climate change (e.g. flesh-footed shearwater—Puffinus carneipes, Australian sea lion—Neophoca cinerea, north Queensland hawksbill turtle—Eretmochelys imbricata, demersal shark species).
Dugong populations in the southern Great Barrier Reef declined to very low levels during the past 50 years, with the aerial survey in 2011 showing the lowest numbers since the surveys began in 1986 (Sobtzick et al. 2012, 2015). In 2015, the Australian Government committed $5.3 million across 3 years for delivery of a Dugong and Turtle Protection Plan, including a Specialised Indigenous Ranger Program for strengthened enforcement and compliance, and an Australian Crime Commission investigation into the illegal poaching, transportation and trade of turtle and dugong meat in the Great Barrier Reef and Torres Strait. Other measures undertaken by local Indigenous people along the length of the Reef include a variety of sea Country management arrangements, including Traditional Use of Marine Resources Agreements and Marine Park Indigenous Land Use Agreements.
Large numbers of species and species groups are not regularly monitored or monitored at all, and, as a result, their status is unknown and recent trends are unclear. Trends were unclear for sharks and rays, most seabirds, sea snakes, some marine turtles and most marine mammals.
There is broad agreement on the current very poor state and deteriorating trend of shorebirds in the past 5 years (see Box BIO13), with consensus and evidence pointing to the causes as habitat loss, habitat degradation and harvest of prey, particularly in east Asia. Current trends in shorebird populations are described in detail in the Coasts report.