Outlook Online 2009

Great Barrier Reef Marine Park Authority :: Frequently Asked Questions

Frequently Asked Questions

What are the effects of fertiliser runoff into the Great Barrier Reef World Heritage Area?

Nutrient input loads to the inshore area of the Great Barrier Reef World Heritage Area have risen by more than 30% following catchment development. The two principal nutrients, nitrogen and phosphorus, exist in several forms in marine waters.

When there is a large concentration of nutrients (phosphorus and nitrogen) in the water, the Reef is affected in a number of ways:

  • Nutrients encourage phytoplankton growth, which leads to decreased water clarity and reduced light for coral and seagrass communities to grow.
  • Phytoplankton growth encourages filter-feeding organisms such as sponges, tubeworms and barnacles to grow, which compete for space with the existing coral community.
  • Nutrients encourage algal growth, which grow over coral communities.
  • Excessive phosphorus weakens the coral skeleton, making it vulnerable to storm damage.

For further information on the effects of fertiliser take a look at the Great Barrier Reef Water Quality: Current Issues report and Research Publication No 68 - Flood Plumes in the Great Barrier Reef: Spatial and Temporal Patterns in Composition and Distribution.

Do herbicides affect seagrasses and corals?

Herbicides such as Diuron are lost from Great Barrier Reef Catchments during rainfall events. The chemicals are washed down rivers and out into the nearshore waters of the Great Barrier Reef World Heritage Area. When this happens, they can affect photosynthesis in seagrass (and possibly other marine algae) and in the zooxanthellae of coral polyps.

What do flood plumes do to the Great Barrier Reef World Heritage Area?

Pollutants are transported to the Great Barrier Reef World Heritage Area mostly during flood events. Floodwaters carry sediments and nutrients that are eroded from the land. A large proportion of the nitrogen and phosphorus carried in flood plumes is attached to fine sediment particles. Heavy metals and pesticides also attach to soil particles are carried out to the marine environment during flood events. For further information regarding flood plumes please refer to Research Publication No 68 - Flood Plumes in the Great Barrier Reef: Spatial and Temporal Patterns in Composition and Distribution.

How far is pollution being carried in the Great Barrier Reef World Heritage Area?

Most pollutants sources from the land are discharged into the Great Barrier Reef World Heritage Area during floods. Flood plumes usually stay relatively close inshore (within 10-15 kms of the coast), but under still conditions or when offshore winds are blowing, flood plumes can reach as far as the outer reef and stay for several days. For further information regarding flood plumes - Have a look at Research Publication No 68 - Flood Plumes in the Great Barrier Reef: Spatial and Temporal Patterns in Composition and Distribution.

How does water quality affect dugongs?

A rapid decline of the dugong population in the Southern Great Barrier Reef Marine Park over the last 10 years has raised concerns about the survival of the species. Land based pollutants from the Great Barrier Reef Catchments are recognised as a threat to dugong populations through degraded water quality. These pollutants may either directly affect them or indirectly contaminate them through seagrasses on which the dugong feed. Loss of feed by smothering and killing seagrasses with sediment is also a concern.

The most important documented potential impact of reduced water quality on dugongs is the effect of herbicides on their seagrass food resource. Herbicides have been found in subtidal sediments in the Great Barrier Reef World Heritage Area in concentrations high enough to effect seagrass health. This may reduce the amount of seagrass, which is available for dugongs to eat. For further information please refer to Research Publication No 66 - Review of Water Quality Issues Influencing the Habitat Quality in Dugong Protection Areas.

How does aquaculture discharge effect water quality?

There are a number of coastal-based aquaculture facilities in catchments adjacent the Great Barrier Reef World Heritage Area. Most of these facilities involve the cultivation of prawns and to a lesser degree finfish (e.g. barramundi). Aquaculture discharges into adjacent waterways can contain high concentrations of suspended solids and nutrients (nitrogen and phosphorus), and may be highly saline, resulting in changes to local salinity regimes. Aquaculture also presents the risk of release of disease to the environment by the accidental introduction of exotic parasites and pathogens to wild stock and other marine species.

Does Water Quality affect Crown Of Thorns Starfish?

The relationship between poor water quality and Crown of Thorns Starfish outbreaks is still unclear. It has been suggested that increased nutrient concentrations can result in increased phytoplankton numbers that are a food source for larval starfish. Other research has suggested that nutrient rich floodwaters can increase survival rates of larval starfish. Research into crown of thorns starfish and reduced water quality is ongoing to resolve these questions.

What are the water quality requirements for effluent released from a wastewater treatment plant into the Marine Park?

The discharge of sewage effluent from fixed structures on islands into the Great Barrier Reef Marine Park is managed under the Sewage Policy 2005 and the Great Barrier Reef Marine Park Regulations 1983.

The Policy stipulates that all discharge of sewage effluent from fixed structures into the Great Barrier Reef Marine Park must be of tertiary treatment standard and this standard is outlined in Regulation 135(3):

Sewage is taken to have received tertiary treatment if the effluent discharge complies with the following standards:

  1. 5 day biochemical oxygen demand does not exceed 20 milligrams per litre;
  2. suspended solids do not exceed 30 milligrams per litre;
  3. pH value is between 6.0 and 8.5;
  4. dissolved oxygen is at least 2 milligrams per litre;
  5. Escherichia coli bacteria organisms in at least 5 samples of the effluent, collected at intervals of not less than half an hour:
    1. have, in respect of all the samples, a geometric mean value
      that is not more than 200 colonies per 100 millilitres; and
    2. number, in 80% of the samples, less than 1000 colonies per 100
      millilitres;
  6. total nitrogen content is less than 4-5 milligrams per litre;
  7. total phosphorus content is less than 1 milligram per litre;
  8. total oil and grease content is less than 10 mg/litre;
  9. the effluent does not produce a slick or any other visible evidence of oil or grease;
  10. if the effluent has been disinfected by chlorination, the effluent does not contain by‑products of the disinfection that may pollute water in a manner harmful to animals or plants in the Marine Park.

Coastal sewage treatment facilities generally have outfalls that are outside the Marine Park and are permitted by the Queensland Environmental Protection Agency under the Queensland Environmental Protection Act 1994 and subject to state policies as outlined in State Coastal Management Plan.

What are the effects of sewage waste discharge (from vessels) on coral reefs?

Typically vessel sewage impacts manifest themselves in the form of excess nutrients and pathogens in the water column. In poorly flushed areas, such as bays and inlets, this results in excess macro-algae growth that will smother corals and impede their growth. It will also result in an excess of micro-algae or phytoplankton growth. These phytoplankton blooms may pose a health risk to humans while also being toxic to other species. When the phytoplankton bloom crashes the bottom waters may become anoxic and therefore toxic to bottom dwelling organisms.

The Great Barrier Reef Marine Park Authority has vessel sewage Regulations that require vessels with holding tanks to retain sewage onboard and only discharge at least 500m away from reefs. The Great Barrier Reef Marine Park Authority is encouraging the development of pump-out facilities to allow for collection and treatment of ship sourced sewage, and has developed guidelines for best environmental construction of marina facilities to include pump out facilities.

Can I discharge vessel sewage into the Great Barrier Reef Marine Park?

Issues regarding vessel sewage are addressed in the Vessel Sewage Regulations for the Great Barrier Reef Marine Park.

How does dredging affect the water quality?

Dredging primarily occurs in the Great Barrier Reef World Heritage Area for development of marinas and maintenance of navigation channels. Dredging of marine sediments can release toxic substances contained in the sediments back into the water column as well as increase the amount of suspended matter in the local area. Resuspended pollutants (such as heavy metals, antifoulants and agricultural pesticides) can have a detrimental impact on marine life that come in contact with them, and increased local turbidity levels can result in smothering of animals and plants as well as reduce the amount of light available to photosynthesising plants.

Why are ships allowed to travel in the inner Great Barrier Reef World Heritage Area?

The underlying principle guiding shipping movements worldwide is that ‘any vessel may not be denied its right of innocent passage’ United Nations Convention on the Law of the Sea 1982. This means that nations such as Australia will generally allow vessels to transit its territorial waters. However in recognition of the environmental sensitivity of the Great Barrier Reef World Heritage Area, the International Maritime Organisation, the shipping industries governing body, declared the Great Barrier Reef World Heritage Area a Particularly Sensitive Sea Area in 1990. This declaration allows the Australian Government to implement initiatives to manage the environmental impact of shipping activities on the Great Barrier Reef World Heritage Area.

Most mariners prefer the inner route between the mainland and the outer reef as it is protected, well charted and marked with navigational aids. This makes this route less hazardous and therefore less likely for incident, than the outer route.

What are the adverse effects of antifouling agents in hull paints?

Antifoulants are used on ships hulls for their biocidal properties to control marine fouling and rely predominantly on combinations of copper and tributyltin (TBT). Deposition of antifoulants at ship grounding sites and at mooring sites and slipways represents a significant risk to marine life. Leaching from antifouling paints, TBT and copper are directly available in the water column.

TBT affects cell metabolism in organisms by causing malformations of the cell membranes, which adversely effects biological functions such as growth and development, reproduction and immune response. Copper can become toxic in elevated levels by the chemical inactivation of cellular enzymes causing interference with critical life functions of organism growth, reproduction and behaviour.

The International Convention on the Control of Harmful Antifouling Systems provides that as of 1st June 2003, all ships will not be able to apply or re-apply organotin (TBT) compounds as an antifouling system.

How does the release of ballast water affect the Great Barrier Reef World Heritage Area?

Ballast water is used to alter the draft, trim and stability of a ship during cargo loading and unloading operations at port and at sea. The introduction of exotic marine species via ships ballast water has become a major environmental concern as it poses threats to local biodiversity, fisheries and aquaculture. Over 250 exotic marine pests (algae, invertebrates and fish) have been introduced to Australia via ballast water discharges and ship hull fouling.

What regulations does the Great Barrier Reef Marine Park Authority apply to tankers that travel through the Great Barrier Reef World Heritage Area?

The Great Barrier Reef Marine Park Authority has several regulations in place to regulate shipping within the Great Barrier Reef Marine Park. These regulations include compulsory pilotage areas, vessel removal orders, and waste and sewage disposal restrictions. The compulsory pilotage Regulations require all vessels over 70 metres to carry a pilot while transiting designated navigationally difficult areas within the Great Barrier Reef Marine Park. These areas are between Cape York and Cairns (the inner route), within the Whitsunday Islands group and Hydrographers Passage (off Mackay). The Great Barrier Reef Marine Park Authority is also able to prosecute vessels for illegal dumping of waste, sewage and litter, as well as requiring vessels to be salvaged from within Great Barrier Reef Marine Park waters.

What role does the Great Barrier Reef Marine Park Authority play in oil spill response?

The Great Barrier Reef Marine Park Authority maintains a high level of pollution response preparedness through training and exercising of staff in the implementation of internal and external response procedures. The Great Barrier Reef Marine Park Authority staff provide advice to the oil spill combat agency (usually Maritime Safety Queensland), to ensure Great Barrier Reef World Heritage Area environmental protection priorities are considered and protected adequately in the event of a shipping incident. In addition, selected Great Barrier Reef Marine Park Authority and Day to Day Management staff have been trained in Shoreline Assessment and Wildlife rescue techniques.

Is drilling for oil or gas allowed in the Great Barrier Reef World Heritage Area?

Drilling for oil and gas and other mining activities are prohibited in the Great Barrier Reef Marine Park, which encompasses approximately 99% of Great Barrier Reef World Heritage Area. The Great Barrier Reef Marine Park Authority has also developed the Great Barrier Reef Region (Prohibition Of Mining) Regulations 1999 to prohibit mining in the Great Barrier Reef Region. Exploration ‘outside’ the Great Barrier Reef World Heritage Area is subject to Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) requirements, if there are likely to be significantly impacts on the Great Barrier World Heritage Area. These proposals would be assessed under the EPBC Act.

What does litter do to the Great Barrier Reef World Heritage Area?

There are a number of ways that litter can end up in the marine environment. Quite often rubbish is dumped overboard from ships whilst at sea. Litter dropped in the streets may also wash into stormwater drains, which could eventually drain into adjacent waterways. Discarded rubbish can have a range of environmental consequences. Rubbish such as plastics and fishing line can entangle wildlife, often resulting in strangulation, limb amputation or drowning. Smaller pieces of rubbish, like cigarette butts and plastics, can be swallowed by marine animals (such as turtles) and cause internal blockages, often resulting in starvation and other complications. There are also economic impacts of rubbish accumulating on our beaches. This includes the loss of aesthetic values in recreational areas that are reliant on tourism –generated income.

How does global warming affect the Great Barrier Reef World Heritage Area?

Naturally occurring gases in Earth’s atmosphere act as a blanket around the earth, and help maintain its temperature. This is known as the greenhouse effect. Since the Industrial Revolution of the late 18th and early 19th centuries, large quantities of these ‘greenhouse gases’ such as carbon dioxide, methane, and nitrous oxide have been added to Earth’s atmosphere as a consequence of human activity. This has led to an increase in the amount of heat from solar radiation trapped by Earth’s atmosphere, leading to warmer global temperatures. Atmospheric carbon dioxide levels are expected to reach double pre-industrial levels by the year 2065. It is predicted that Earth’s temperature will continue to rise by approximately 0.3 ºC per decade as a consequence of increased atmospheric concentrations of greenhouse gases, and this is estimated to result in an increases in sea temperature of 1 oC to 2 oC by 2100. Elevated seawater temperatures will bleach and ultimately kill corals. See our general information on Coral Bleaching for an introduction to this phenomenon.

What actions are been undertaken to improve water quality entering the Great Barrier Reef World Heritage Area?

Please refer to the Reef Water Quality Protection Plan of our website for details.

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