SIGNAL scoring system for river bio-assessment by community groups
Land & Water Australia. 2009. SIGNAL scoring system for river bio-assessment by community groups. [Online] (Updated July 30th, 2009)
Available at: http://lwa.gov.au/node/3649 [Accessed Friday 27th of February 2015 04:59:09 PM ].
SIGNAL stands for ‘Stream Invertebrate Grade Number – Average Level.’ It is a simple scoring system for macro-invertebrate (‘water bug’) samples from Australian rivers.
A SIGNAL score gives an indication of water quality in the river from which the sample was collected. Rivers with high SIGNAL scores are likely to have low levels of salinity, turbidity and nutrients such as nitrogen and phosphorus. They are also likely to be high in dissolved oxygen.
When considered together with macro-invertebrate richness (the number of types of macro-invertebrates), SIGNAL can provide indications of the types of pollution and other physical and chemical factors that are affecting the macro-invertebrate community.
SIGNAL was first developed in 1993 for use in the Hawkesbury–Nepean River system near Sydney, and especially for assessing the impacts of discharges from sewage treatment plants. The original SIGNAL was a preliminary version, because knowledge of the distributions and tolerances of Australian river macro-invertebrates was limited at that time. Most of the knowledge that did exist was for south-eastern Australia, and the original SIGNAL was difficult to apply in northern, western and inland Australia.
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