Water Turbidity

AUS-TMI-AQU-WTU General Moderate confidence

Benchmark Value

24 NTU
Direction: Lower is desirable ↓
Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard OptimalRange Guard Point Guard MaximumOnly Guard MaximumOnly Guard MaximumOnly Guard MaximumOnly Guard OptimalRange Guard MaximumOnly Guard Point Guard LowerThreshold Guard OptimalRange Guard MaximumOnly Guard MaximumOnly Guard

Evidence & Context

Synthesizing these findings, a conservative upper detrimental threshold can be established at >24 NTU, where clear, negative impacts on fish behavior and ecosystem function are documented.

Metric Definition:

Water Turbidity is a measure of the degree to which water loses its transparency due to the presence of suspended particulates, quantified in Nephelometric Turbidity Units (NTU).

Benchmark Definition:

This benchmark defines an upper detrimental turbidity threshold of 24 NTU, beyond which significant negative impacts on fish behavior and ecosystem function occur in the Tropical & Subtropical Maritime Islands biome under aquaculture land use.

Justification:

The threshold is based on observed behavioral changes in fish and ecosystem function decline at turbidity levels above 24 NTU.

Sources (2)

Preview of Australis First in World to Achieve Tropical Marine Finfish ASC Certification, accessed August 1, 2025,
Australis First in World to Achieve Tropical Marine Finfish ASC Certification, accessed August 1, 2025, GreyLiterature

Turbidity Characteristics of The Waters on The ... - Omni-Akuatika

View Source
Preview of Sensory compensation and the detection of chemical alarm cues by a coral reef fish
Sensory compensation and the detection of chemical alarm cues by a coral reef fish Journal

Sensory compensation and the detection of chemical alarm cues by a coral reef fish

View Source

Supporting Sources (20)

Additional references from the underlying research that informed this benchmark.

Preview of Acropora tenuis energy acquisition along a natural turbidity gradient - Frontiers, accessed August 1, 2025,
Acropora tenuis energy acquisition along a natural turbidity gradient - Frontiers, accessed August 1, 2025,
Contextual Support Journal

Acropora tenuis energy acquisition along a natural turbidity gradient - Frontiers, accessed August 1, 2025,

View Source
Preview of Aquaculture species | NT.GOV.AU, accessed August 1, 2025,
Aquaculture species | NT.GOV.AU, accessed August 1, 2025,
Contextual Support Government

Aquaculture species | NT.GOV.AU, accessed August 1, 2025,

View Source
Preview of Black tiger prawn aquaculture | Business Queensland, accessed August 1, 2025
Black tiger prawn aquaculture | Business Queensland, accessed August 1, 2025
Contextual Support Government

Freshwater aquaculture | Business Queensland, accessed August 1, 2025

View Source
Preview of Cocos (Keeling) Islands Marine Park, accessed August 1, 2025,
Cocos (Keeling) Islands Marine Park, accessed August 1, 2025,
Contextual Support Government

Cocos (Keeling) Islands Marine Park, accessed August 1, 2025,

View Source
Preview of Developing a reef water quality management plan — case study, accessed August 3, 2025,
Developing a reef water quality management plan — case study, accessed August 3, 2025,
Contextual Support Government

Altered water flows and quality | Wet Tropics Management Authority, accessed July 27, 2025

View Source
Preview of Environmental Code of Practice for Australian Prawn Farmers - NTEPA, accessed August 1, 2025,
Environmental Code of Practice for Australian Prawn Farmers - NTEPA, accessed August 1, 2025,
Regulatory Framework Journal

Environmental Code of Practice for Australian Prawn Farmers - NTEPA, accessed August 1, 2025,

View Source
Preview of ESR/2015/1683 Wastewater licencing from existing marine prawn farms, accessed August 1, 2025,
ESR/2015/1683 Wastewater licencing from existing marine prawn farms, accessed August 1, 2025,
Regulatory Framework Journal

ESR/2015/1683 Wastewater licencing from existing marine prawn farms, accessed August 1, 2025,

View Source
Preview of gbr-dredge-material-management-appendixb.docx - DCCEEW, accessed August 1, 2025,
gbr-dredge-material-management-appendixb.docx - DCCEEW, accessed August 1, 2025,
Contextual Support Journal

Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments - PMC, accessed August 1, 2025,

View Source
Preview of Important Water Quality Parameters in Aquaculture: An Overview - ResearchGate, accessed August 1, 2025,
Important Water Quality Parameters in Aquaculture: An Overview - ResearchGate, accessed August 1, 2025,
Contextual Support GreyLiterature

Important Water Quality Parameters in Aquaculture: An Overview - ResearchGate, accessed August 1, 2025,

View Source
Preview of Interactive effects of sedimentary turbidity and elevated water temperature on the Pugnose Shiner (Miniellus anogenus), a threatened freshwater fish | Conservation Physiology | Oxford Academic
Interactive effects of sedimentary turbidity and elevated water temperature on the Pugnose Shiner (Miniellus anogenus), a threatened freshwater fish | Conservation Physiology | Oxford Academic
Contextual Support Journal

To fear or to feed: the effects of turbidity on perception of risk by a ..., accessed August 1, 2025,

View Source
Preview of National Guidelines for Water Quality - Department of Natural Resources and Environment Tasmania, accessed August 1, 2025,
National Guidelines for Water Quality - Department of Natural Resources and Environment Tasmania, accessed August 1, 2025,
Regulatory Framework

Using the ANZECC Guidelines and Water Quality Objectives in NSW

View Source
Preview of Queensland Aquaculture Policy Statement - The Queensland ..., accessed August 1, 2025,
Queensland Aquaculture Policy Statement - The Queensland ..., accessed August 1, 2025,
Regulatory Framework Journal

Queensland Aquaculture Policy Statement - The Queensland ..., accessed August 1, 2025,

View Source
Preview of Queensland Aquaculture Strategy 2024–2034, accessed August 1, 2025,
Queensland Aquaculture Strategy 2024–2034, accessed August 1, 2025,
Regulatory Framework Government

land and water | Queensland Government

View Source
Preview of Review of Nutrient Release from Aquaculture ... - Griffith University, accessed August 1, 2025
Review of Nutrient Release from Aquaculture ... - Griffith University, accessed August 1, 2025
Contextual Support Journal

Review of Nutrient Release from Aquaculture Activities Final Report - Griffith University

View Source
Preview of Turbidity and light attenuation in coastal waters of the Great Barrier Reef - ResearchOnline@JCU, accessed August 2, 2025,
Turbidity and light attenuation in coastal waters of the Great Barrier Reef - ResearchOnline@JCU, accessed August 2, 2025,
Direct Evidence Journal

Turbidity and light attenuation in coastal waters of the Great Barrier Reef - ResearchOnline@JCU

View Source
Preview of Turbidity Characteristics of The Waters on The ... - Omni-Akuatika
Turbidity Characteristics of The Waters on The ... - Omni-Akuatika
Contextual Support Journal

Turbidity Characteristics of The Waters on The ... - Omni-Akuatika, accessed August 1, 2025,

View Source
Preview of Using the ANZECC Guidelines and Water Quality Objectives in NSW, accessed August 11, 2025,
Using the ANZECC Guidelines and Water Quality Objectives in NSW, accessed August 11, 2025,
Regulatory Framework Journal

Reference-site data - Water Quality Australia

View Source
Preview of Wastewater remediation options for prawn farms, accessed August 1, 2025
Wastewater remediation options for prawn farms, accessed August 1, 2025
Contextual Support Journal

Enhancing Nitrate Removal from Freshwater Pond by Regulating Carbon/Nitrogen Ratio - Frontiers, accessed July 24, 2025,

View Source
Preview of Water Quality - GBRMPA eLibrary, accessed August 1, 2025,
Water Quality - GBRMPA eLibrary, accessed August 1, 2025,
Contextual Support

Catchments and corals: terrestrial runoff to the Great Barrier Reef - The Australian Institute of Marine Science, accessed July 28, 2025,

View Source
Preview of Water Quality Guidelines for the Great Barrier Reef Marine Park., accessed August 3, 2025,
Water Quality Guidelines for the Great Barrier Reef Marine Park., accessed August 3, 2025,
Regulatory Framework Journal

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management - PubMed Central

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Aquaculture
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 1 Jun 2026

Notes

At 24 NTU, fish exhibited marked behavioral changes, including reduced activity and foraging, indicating a high level of stress. Other research notes that high turbidity can directly harm fish by clogging gills and reduce physiological resilience. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TMI-AQU-WTU family.

4.5 NTU Moderate
Aquaculture · Not Stated
Point Active v1