Issues, pressures and threats

Risk of ship groundings and collisions

One of the main risks posed by shipping is a major spill of chemicals or oil resulting from a grounding or collision.

One of the greatest risks shipping poses to the Great Barrier Reef is a major oil spill. Since 1987 over 700 shipping or marine pollution incidents have been reported in the Great Barrier Reef Marine Park Authority’s marine incident database. However, most of these reports involve small spills of petroleum products (for example, from bilge pump outs), sinking vessels or groundings and many reports are unsubstantiated (see Table 2). Reports of shipping or marine pollution incidents are increasing, but this may be due to improved awareness and reporting arrangements.

Table 2: Shipping and Pollution Incidents in the Great Barrier Reef World Heritage Area for 2000- 2004 (data from the GBRMPA marine Incident database)

Between 1987 and 2004, only 33 of the 700 incidents recorded (including 11 collisions and 22 groundings) were considered significant, however, none of these incidents resulted in major spills of oil or chemicals. In recent years, significant ship groundings include the following:

• MV Global Peace – Gladstone Harbour on 24 January 2006
• MV Karma – stranding near Agnes Waters on 14 November 2003
• MV Doric Chariot – Piper Reef in July 2002 
• MV Bunga Terati Satu – Sudbury Reef in November 2000 
• MV New Reach – Heath Reef in May 1999
• MV Peacock – Piper Reef in July 1996
• MV Svendborg Guardian – Kurramine Beach in June 1995
• MV Carola – South Ledge Reef in March 1995

Significant shipping incidents also include situations where a ship grounding or spill does not occur. For example, in April 2004, the engine of the bulk carrier MV Harmonic Progress became disabled approximately 90 nautical miles north of Hydrographers Passage. The vessel drifted for 43 hours and came within 30 nautical miles of the Great Barrier Reef until tugs were able to stabilise the vessel’s drift. While the ship was prevented from grounding, adverse weather conditions could have resulted in the disabled ship grounding on the Great Barrier Reef, potentially causing a major spill of oil and cargo.

Figure 1. Map showing sensitive shipping areas within the Great Barrier Reef Marine Park (click to enlarge map).

In 2000, a joint study conducted by Maritime Safety Queensland and the Great Barrier Reef Marine Park Authority identified the areas of the Marine Park at highest risk from shipping incidents (see Figure 1). This report (Oil Spill Risk Assessment for the Coastal Waters of Queensland and the Great Barrier Reef Marine Park)¹² identified the following areas of highest risk of a shipping incident:

• Inner Route of the Great Barrier Reef (north of Cape Flattery)
• Port of Cape Flattery
• Whitsunday Islands (predominantly cruise shipping)
• Hydrographers Passage
• Great North East Channel

Consistent with national trends, ship groundings and collisions have been identified as the most likely type of shipping accident to occur in the Great Barrier Reef. In 1995, the Department of Transport’s Great Barrier Reef and Torres Strait Shipping Study categorised the factors contributing to the risk of either collisions or groundings.² The study found that the risk of an incident may depend on how closely ships approach reefs or land, the presence of trawlers, and whether ships had coastal pilots on board.

A study on shipping risks in the Great Barrier Reef suggested that a range of control measures could reduce the rate of incidents from 2.5 to 1.9 per year, with particular improvement in the Torres Strait region.³ Many of these controls were proposed as recommendations in the 2001 Review of Great Barrier Reef Shipping Safety and Pollution Prevention Measure (the Review) and almost all 41 recommendations of the Review have been implemented (see Response: Legislation, conventions and management arrangements applying to shipping in the Great Barrier Reef Marine Park). 

Potential impacts of ship operations

While shipping activities are a vital component of Australia’s economy, shipping operations may affect the economic, environmental, social and cultural values of the Great Barrier Reef. Environmental risks related to shipping within the Great Barrier Reef can occur from the routine discharge of pollutants during normal ship operations, or as a result of accidents or incidents. Potential impacts include:

• Spills or discharges of oil, chemicals, cargo, sewage and grey water
• Garbage and marine litter
• Collisions with marine animals
• Disturbance of marine life by noise
• Toxic effects of anti-fouling paints
• Physical damage from groundings and anchoring
• Ecosystem changes resulting from the introduction of invasive marine pests

Impacts from spills of oil or cargo

The accidental release of fuel or cargo resulting from groundings, collisions or structural failures may result in serious environmental damage to the Great Barrier Reef. The environmental consequences of an oil spill will likely depend on factors such as the type of oil and amount spilled, weather conditions and the habitats affected. The main threats to wildlife include the smothering of animals, plants or habitats by oil, and poisoning of animals that ingest the oil. Oil spills may also result in social and economic impacts through damage to habitats and organisms important to the Marine Park tourism and fishing industries, and the loss of access to or use of affected areas by recreational users or traditional owners.

Heavy fuel oil is the most damaging type of oil as it does not break down quickly and is difficult to disperse or remove. In contrast, light fuels such as diesel tend to be more toxic to marine life and readily disperse in the water column. This makes the containment and removal of these oils more difficult. Because most oils float, habitats that are exposed at low tide such as mudflats, mangroves and inter-tidal seagrass beds and beaches are especially vulnerable. However, over time oil slicks may be broken up by sunlight, bacteria and wave action, mixing oil droplets or residues through the water column.

Oil spills pose a serious potential threat to the animals and plants of the Great Barrier Reef. Relatively small ‘operational’ spills present an ongoing problem

Apart from the physical smothering of plants and animals, the toxicity of oil is likely to affect the health, growth, reproduction and development of a range of marine plants and animals for several years. The severity of such effects may depend upon oil type, concentration and the extent of exposure. Smaller accidental releases of petroleum products during fuel transfer operations and illegal discharges of bilge waste may contribute to localised impacts on habitats and fauna. These small-scale spills are relatively costly to respond to, diverting disproportionate resources from other areas or incidents.

Little is known about the potential environmental impacts of spills of other cargoes that are carried by ships transiting the Great Barrier Reef. Few studies have been conducted on the sensitivity of plants and animals to chemicals transported along the Queensland coast used in the production of metals (for example, copper and nickel), industrial products (for example, cement) or agricultural products, such as sugar.
 

Case study: the Gladstone Harbour oil spill At 11:54pm on the 24 January 2006, a tugboat struck the hull of the Korean bulk carrier MV Global Peace that was entering Gladstone Harbour to berth at the RG Tanna coal terminal. The impact ruptured a hull fuel tank and resulted in approximately 25 tonnes of heavy fuel oil spilling into Gladstone Harbour. The National Plan to Combat Pollution of the Sea by Oil was immediately activated with Maritime Safety Queensland leading a multi agency team to combat the spill. Expertise and assistance were sourced from around Australia and overseas. As per the National Plan, the Queensland Environmental Protection Agency and the Great Barrier Reef Marine Park Authority provided advice on environmental aspects of the response. The clean up efforts were assisted with pre-positioned equipment readily available at the site. By the first day, booms and skimmers had been deployed to contain the slick and approximately two tonnes of oil and debris had been recovered. By the second day, skimmers had arrived from other locations and four skimmers were operating. Unfortunately, a storm and poor weather hindered recovery efforts and broke one of the protective booms, allowing oil to penetrate the mouth of Auckland Creek and enter the Gladstone Marina. While the slick formed a band up to 20km long and 4km wide, winds and waves contained most of the slick within the port. This concentrated the slick, making it easier for skimmers to remove it and preventing it from spreading into the Great Barrier Reef Marine Park. Shoreline assessments were carried out at several locations and revealed that high tides had deposited oil on harbour breakwaters and carried it into mangroves. In affected areas, the oil covered mangrove roots and extended up trunks and leaves to the high tide mark. The oil also washed up on beach areas and penetrated the sand. Fortunately, the oil did not spread to bird foraging grounds and only a dozen birds were observed to have been oiled. No other oiled wildlife was reported. Concerns were raised about the potential for oil to contaminate seafood caught in the area, but samples analysed by the Queensland Department of Primary Industries and Fisheries and Queensland Health have not shown any signs of contamination.   On 24 January 2006, a tugboat struck the hull of the MV Global Piece. Response was rapid and together with favourable weather conditions, the oil was prevented from entering the Great Barrier Reef Marine Park. Image taken by Jamie Storrie, Department of Environment and Heritage  Over the eight-day operation, some 8000 litres of oil was recovered and 61 cubic meters of oily debris removed from beaches and mangroves.10 The top layers of sand were removed from the swimming beach and the marina was scrubbed clean by hand. The Queensland Environmental Protection Agency and the Queensland Department of Primary Industries and Fisheries are assessing the long-term impacts on mangroves and wildlife. Monitoring to date has found that the impact on seagrasses have been limited, with no obvious effects on seagrass beds except for small, isolated patches of dead seagrass found on Wiggins Island. Surveys of the affected area have also found signs of new seagrass colonisation. Leaf loss and mangrove dieback has occurred in patches, however the full impacts may not be known until October 2006. Aerial surveys conducted in future months will provide a more complete assessment. Samples of mangrove, algae, seagrass and sediments have been collected through the Integrated Port Curtis Monitoring Programme for signs of contamination. The rapid response in combating the oil spill has highlighted the value of thorough preparation and planning, regularly exercising of contingency plans and of having equipment and properly trained staff available to mount a prompt response.

Collisions with marine animals

Collisions with animals such as whales and dugongs are a potential impact of shipping activity. This dugong (above) shows signs of propeller scars.

Collisions or ‘boat strikes’ between vessels and marine wildlife have been identified as a pressure on whales, dolphins, dugongs and marine turtles. These animals may be struck by ships, resulting in internal injuries, or cut by propellers. The noise generated by boats and ships may also disturb these animals and/or displace them from habitats. The impacts of shipping and boating activities on marine animals are discussed in more detail in the following chapters: Environmental status – marine mammals and Environmental status – marine reptiles.

Impacts of antifoulant paint and ship groundings

The build up of organisms such as algae and barnacles on hulls and propellers can significantly reduce the speed and efficiency of vessels. Until recently, the hulls of ships were painted with antifoulant paint to reduce the growth of algae and other organisms. Antifoulant paints contain combinations of toxic chemicals such as copper, Tri-butyl Tin (TBT) and diuron. Antifoulant paint residues left behind in the ship’s wake, or scraped onto the reef in the case of grounding, can result in long-term localised damage to the marine environment. During a ship grounding, significant quantities of concentrated antifoulant chemicals containing copper, zinc, TBT or other toxic chemicals can be scraped off the vessel, contaminating the sand and coral rubble. These compounds can have long-term effects, by hindering the recolonisation of the damaged site by corals and other marine organisms.^5,13

Ship groundings can leave large scars in the reef, as evident in the photo above of the MV Doric Chariot being pulled off Piper Reef in the Northern Great Barrier Reef, July 2002.

Ship groundings can result in significant localised damage to habitats. Groundings often leave grounding scars in the reef substrate where the coral is crushed and compacted. The instability of remaining coral rubble and changes to the water flow in the affected area have been found to hinder the settlement of new corals, delaying the recovery of the grounding scar. These physical factors, combined with the effects of antifoulant paint residues, mean that recovery of grounding scars may take decades. Grounding scars may also allow water to drain out of reef lagoons at low tide, potentially increasing erosion and exposing shallow water corals and lagoon habitats at low tide.

Ship groundings can also have significant social and cultural impacts. For example, Piper Reef and its surrounds are areas of cultural and historic importance to Indigenous communities in the region. Over the last decade, Piper Reef has sustained damage from several ship groundings and the Kuku Yau Traditional Owners from the area now consider the area to be contaminated and a place where it is bad luck to conduct diving, fishing and hunting activities (Chicka Turner, pers comm).

Impacts of waste discharge

Ships transiting the Marine Park may carry anywhere from a few to hundreds of people, and can generate considerable volumes of sullage. High concentrations of nutrients in sewage and grey water can disrupt the physiological and reproductive processes of corals and ecological balance of coral reef systems. These pollutants may contribute to excessive algal blooms and weakening of the coral skeleton (see Environmental status – water quality). Although most cruise ships and cargo trading ships have sewage treatment systems on board to treat sewage, not all commercial and recreational vessels using the Marine Park manage their sewage to the same standards. However, more stringent and uniform regulations were recently introduced to regulate the discharge of sewage from all types of vessels operating in the Marine Park (see Management actions applying to shipping in the Great Barrier Reef Marine Park).

Marine debris and litter

Around the world, marine debris and litter blown, washed off or dumped from ships into the water is a growing issue. A report titled Finding Solutions commissioned by the Australian Government National Oceans Office found that most of the debris and litter washed up on the northern Australian coast is of marine origin. This includes lost fishing gear as well as litter and debris from commercial shipping and recreational vessels. While lost fishing gear was a relatively small proportion of the debris found, it was the most significant in terms of weight and potential impact.⁷ In 1996, a survey of coral cays in the Great Barrier Reef identified that plastics, rubber and glass objects were the most common items washed up on beaches. However, there is little information about the volume, origins and fate of marine debris in the Great Barrier Reef.

The Australian Government has recognised marine debris as a Key Threatening Process for species such as whales, dolphins, birds and marine turtles. Marine debris poses a threat to wildlife through entanglement or ingestion. Entanglement in marine debris may result in the animal losing mobility, starving, losing limbs, suffering from infected wounds or drowning. Ingested debris can result in intestinal blockages or internal injuries that lead to the death of the animal.

Introduced marine species

Ships can unintentionally introduce exotic marine plants and animals to the Great Barrier Reef through ballast water exchange  or hull fouling. Once introduced, these new organisms can potentially colonise an area and out-compete, overgrow and kill native plants and animals. These ‘invasions’ can lead to major ecosystem disturbances that reduce biodiversity and affect industries such as fisheries, tourism, aquaculture and port operations.

The likelihood of an exotic marine pest being introduced into local waters depends on factors such as the volume of ballast water discharged into receiving ports, and the surface area of vessels entering the port that are fouled with such organisms.⁴ However, fouling organisms are often most numerous in small nooks and crannies in and around a vessel. The degree of fouling is highly dependant on the vessels activity patterns, the time since it was last cleaned and antifouled and the type of antifoulant used.⁴ Once it arrives, the potential for an introduced marine species to survive and colonise a new area depends on factors such as ship movement patterns, how similar the receiving environment is to the port of origin, larval survival rates and larval population densities.⁴

Hull fouling is a potential vector for the spread of pests. Organisms settle on the hull, propeller, sea chests and other parts of ships and are transported to other sites where they may become a pest.

Almost half of the 11 000 ships on international voyages that enter Australian waters are bulk carriers that generally arrive either in full ballast or with a full complement of cargo. Most of the bulk carriers arriving in Queensland ports are from Korea and Japan. These ships pose a lesser risk of introducing pest species as the ports of origin in Korea and northern Japan are in cool waters, and organisms transported in ballast water from these ports are unlikely to survive in the warmer waters of Queensland.⁶ However, ships arriving from the warmer ports of southern Japan, Singapore and Taiwan, may carry organisms that can survive in Queensland waters. The ports of Hay Point and Gladstone have the highest shipping traffic on the Great Barrier Reef coast, and the highest levels of ballast water discharge.

A recent CSIRO report found that within Australian waters, there are some 534 marine and estuarine species that have potential ‘invasion characteristics’. Of these species, 100 are native; 133 are non-native; 175 are cryptogenic; whilst the invasion status of the remaining 126 species is unknown.⁴ There is relatively little information about the occurrence and distribution of introduced marine species, or their impacts on the ecosystems of the Great Barrier Reef. While major outbreaks of introduced marine species have not been detected in the Great Barrier Reef region, isolated incursions of the Asian green mussel (Perna viridis) and Caribbean tubeworm (Hydroides sanctaecrucis) have occurred in ports and harbours adjacent to the Marine Park such as Trinity Inlet in Cairns. Although both species have the potential to become serious pests, these incursions have not resulted in widespread ecological damage. Further research into the occurrence and distribution of introduced marine pests, and techniques to manage them, is underway (see Management of introduced marine species).