Marine water quality guidelines

The following has been extracted from the Great Barrier Reef Marine Park Authorities Water Quality Guidelines.  The Water Quality Guidelines for the Great Barrier Reef Marine Park(2008) provide tolerances for a range of contaminants based on their effects on marine aquatic ecosystems. The trigger values derived in this guideline are presented in the following tables. Parameters that are not listed here default to the Queensland Water Quality Guidelines 2006, which in turn default to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality 2000.

Parameter	Enclosed coastal (Wet Tropics/Central Coast)	Coastal	Inshore	Offshore
Chlorophyll a (ug/L)	2.0	0.45	0.45	0.4
Secchi depth 1 (m)	1.0/1.5	10	10	17
SS (mg/L)	5.0/15	2.0	2.0	0.7
PN (ug/L)	na	20	20	17
PP (ug/L)	na	2.8	2.8	1.9

Guideline trigger values for water clarity need to be decreased by 20 per cent for areas with greater than 5 m tidal ranges.

For the following parameters, direct effects on biota occur, regardless of water body, if trigger values are exceeded. Therefore, only single values are set and apply equally to the water bodies.

Parameter	Guideline trigger value
Sedimentation rate	Maximum mean annual sedimentation rate of 3 mg/cm2/d, and a daily maximum of 15 mg/cm2/d
Sea temperature	Increases of no more than 1°C above the long-term average maximum

High, moderate and low reliability guideline trigger values were derived for listed pesticides, and for tributyltin, where sufficient marine specific data were available. Where there was insufficient data the trigger values from the Australian and New Zealand Guidelines for Fresh and Marine Water Quality 2000 are repeated here. All pesticide and biocide trigger values are set to be protective of 99 per cent of species. 

Pesticide	Trigger value, ug/L
	High reliability
Chlorpyrifos	0.005
	Moderate reliability
Diuron	0.9
Atrazine	0.4
Ametryn	0.5
2,4-D	0.8
Endosulfan	0.005
	Low reliability
Simazine	0.2
Hexazinone	75a
Tebuthiuron	0.02
MEMC	0.002
Diazinon	0.00003

 ^a This trigger value may not protect keystone species given sub lethal effect concentrations for adult coral colonies are observed at significantly lower concentrations. Research is recommended to better quantify potential impacts.

Biocide	Moderate reliability guideline trigger value, ug/L
Tributyltin	0.0002

The trigger values identified above are not targets, but are guideline values that, when exceeded, should trigger management responses.

 

De'ath and Fabricius, 2008:

Water quality in the GBR

Figure 5. Locations that are presently at less than (green) or exceed (orange and red) the water quality guideline trigger value of a maximum annual mean of 0.45 μg L-1 chlorophyll. Orange zones show areas that exceed the guideline trigger values, having chlorophyll values of 0.45 – 0.8 μg L-1. Red zones show areas of greatest concern with >0.8 μg L-1 chlorophyll. The level of fading (right panel) indicates the level of confidence in the estimates with faded areas being more uncertain.

Figure 6. Locations that are presently at less than (green) or exceed (orange and red) the water quality guideline trigger value of a minimum annual mean of 10 m Secchi depth. Orange zones show areas that exceed the guideline trigger values, having Secchi depths of 5 – 10 m. Red zones show areas of greatest concern with Secchi depth <5 m. The level of fading (right panel) indicates the level of confidence in the estimates with faded areas being more uncertain.

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Citation and/or URL

Great Barrier Reef Marine Park Authority (2008). Water Quality Guideline for the Great Barrier Reef Marine Park. Great Barrier Reef Marine Park Authority, Townsville

De'ath, G. & Fabricius, K.E. 2008, Water quality of the Great Barrier Reef: distributions, effects on biota and trigger values for the protection of ecosystem health: final report to the Great Barrier Reef Marine Park Authority. Research Publication 89, Great Barrier Reef Marine Park Authority, Townsville, Australia

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Spatial Coverage

Great Barrier Reef Marine Park

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Temporal Coverage

Chlorophyll, nutrient and secchi data collected since 1976

Hard coral biodiversity data between 1994 and 2001 

Reef Plan Marine Monitoring Program since 2005 

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Update Frequency

Annually

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Other Information

None