International vessels operating in Australian waters mainly comprise large cargo carriers, but may also include smaller commercial ships, cruise vessels and international yachts. As an island, Australia relies heavily on commercial vessels for transportation of its imports and exports. In 2013–14, 1425 million tonnes of cargo moved across Australian wharves, 1221.8 million tonnes of which were international exports and imports. A total of 5499 vessels made 28,714 port calls in 2013–14 (BITRE 2015). International exports comprised 85.7 per cent of this cargo, whereas international imports represented 7 per cent. In addition, there were 670 cruise ship visits.
Very few places in the Australian marine environment are not used by marine vessels (Figure MAR16). Major routes used by vessels traverse a wide variety of habitats and ecosystems, and groundings by vessels and accidents at sea in ecologically sensitive areas impose pressures on the marine environment. Since 2011, 4 ships have been reported as grounded, all within embayment or port areas, and 3 vessels have been involved in collision, capsizing or foundering events.5 Vessels also interact directly with marine animals via vessel strike (see Box MAR3) and emit constant noise into the ocean (see Anthropogenic noise). Vessels are a source of atmospheric emissions, including carbon dioxide, nitrous oxide and sulfur. Anchoring in offshore areas can cause sea-floor abrasion and damage to benthic ecosystems (Davis et al. 2016). The exchange of ballast water in nearshore port or mooring environments and biofouling of vessels can introduce foreign marine species to the Australian environment. Biocides used in antifouling paints are toxic when released to the marine environment, and can affect marine species’ growth and reproduction, mainly when the coating is dislodged from the hull or through the coating dissolution process in confined inshore waters (see Thomas & Brooks 2010).
The National Plan for Maritime Environmental Emergencies (NESMG 2014) sets out the cooperative arrangements between government and industry to respond to maritime incidents affecting the environment (see also Effectiveness of marine management).