Annual Water-bug monitoring in Rapid Creek

Annual monitoring of stream health is currently undertaken in Rapid Creek and uses an assessment system known as AUSRIVAS. This stands for Australian River Assessment System, and works by comparing water-bugs present in a stream with those expected to be present in reference streams of a similar type.

Why monitor water bugs?

Organisms living in streams and rivers are biological indicators that can tell us about the condition or “health” of waterways. Diverse communities of macroinvertebrates (or water-bugs) indicate a stream in good condition, whereas simple communities of few water-bug types indicate a damaged or degraded stream.

How does it work?

AUSRIVAS produces a score based on the number of types found in a sample relative to the number of types expected. To simplify interpretation of these scores a banding system has been developed (see table below). Band A means streams are equivalent to high quality reference steams; bands B, C, or D indicate that the stream is below reference condition and is degraded to varying degrees.

Monitoring Results for Rapid Creek 2017

Two sites were sampled for water bugs in 2017. These sites are in the upper reaches of the Rapid Creek system which is a small seasonally flowing stream in the Darwin urban area.

The sites received scores of B and a C  respectively, typical of a stream with an urbanised catchment that has a slightly impoverished water bug community. These results are similar to previous years as shown in the table below.

Interpretation of AUSRIVAS Bands

Last updated: 22 May 2018