THE HEALTH OF STREAMS IN THE CAMPASPE, LODDON AND AVOCA CATCHMENTS Publication 704 June 2000 Introduction Careful management of our waterways and Having undertaken biological monitoring in Victoria catchments is crucial to maintain and improve river since 1983, EPA has a great deal of experience in health. Good decision making requires detailed the field. The results of previous studies will be information on the environmental condition of our combined with those of the current program, providing rivers. a solid background of data. This will be used to determine long term trends in the health of our rivers The Monitoring River Health Initiative (MRHI) – a and will help the protection of water quality and the biological monitoring program across Australia – was beneficial uses of our water courses. introduced as part of the National River Health Program funded by the Commonwealth. The main aim of the MRHI was to develop a standardised biological Monitoring water quality assessment scheme for evaluating river health. This Traditional water quality monitoring involves measuring was to be achieved by sampling reference sites and physical and chemical aspects of the water. Common using the information collected to build models to predict measurements include pH, salinity, turbidity, nutrient which macroinvertebrate families would be expected levels, toxic substances and the amount of oxygen to occur under specified environmental conditions. In dissolved in the water. These measures provide a Victoria the program was conducted by the ‘snapshot’ of environmental conditions at the moment Environment Protection Authority (EPA) and AWT samples are taken. Water quality conditions are Victoria (formerly Water EcoScience). In urban areas, variable, so such monitoring can fail to detect this is also complemented by Melbourne Water’s occasional changes or intermittent pulses of pollution. Healthy Waterways program. In contrast, the biological monitoring program involves Currently, an Australia-wide Assessment of River sampling aquatic animals, which gives an indication Health (AWARH) is being conducted under the of the health of the river as a whole. Because they National Rivercare Program to assess the health of live at the site for some time, animals reflect the build- Australia’s rivers. EPA is sampling approximately 600 up of impacts of environmental change on the river test sites in Victoria and evaluating these against the ecosystem – such as the influence of surrounding MRHI models. land use or the effects of pollution. 1 Biological monitoring techniques from shallow areas with stony or rocky substrates in Aquatic macroinvertebrates (such as insects, snails medium to fast currents. This type of habitat is called and worms) are very useful indicators in biological a riffle and is usually associated with upland streams. monitoring. They are visible to the naked eye and are In sandy streams, shallow fast flowing sandy areas commonly found in rivers and streams. They are an are sampled. important source of food for fish and many are well ◆ Sweep samples for edge habitat known to anglers – such as yabbies, mudeyes, Sweep samples are collected by sweeping a net along stoneflies and mayflies. They are widespread, easy banks and around snags in backwaters and pools to collect, relatively immobile and provide good which have slow currents or no flow. Aquatic plants information about the environment. (macrophytes) – which provide additional habitat for The presence or absence of specific species provides aquatic animals – are often found in these edge information about water quality. Some species are habitats and are included in the sweep sample. These known to have particular tolerances to environmental habitats can be found in both the upland and lowland factors such as temperature or levels of dissolved reaches of rivers. oxygen. Other information can be obtained from the Water quality measurements – including dissolved number of species found at a site (biological diversity), oxygen, pH, temperature and electrical conductivity – the number of animals found at a site (abundance) are made at each site and water samples are taken for and the relationship between all animals present laboratory analysis of nitrogen and phosphorus levels (community structure). and turbidity. The vegetation along the river banks (the Sites with a high level of species diversity generally riparian zone) and the aquatic habitat are also assessed. have good water quality. Sites which have low The aquatic habitat is those parts of the river diversity are less healthy – often due to the impacts environment which animals use to make a home. It of pollution. In polluted habitats, sensitive species are can be strongly affected by the streamside vegetation eliminated and less sensitive species show an increase as well as the environment and land use of surrounding in numbers. and upstream regions. The water quality and habitat measurements, taken at the same time as the biological samples, are also used in modelling and other data Study site selection and analyses. assessment For example, if fertiliser runoff is causing an excess Sites are selected to include a variety believed to be of nutrient to enter the river, there may be excess representative of the river basin’s waterways – growth of algae attached to rocks and snags in the including sites that are relatively unimpacted river, affecting these important habitats. It can also (reference) and sites which are subject to the impact result in blooms of toxic blue-green algae which are of pollution (test), although most of these are situated potentially hazardous to humans, animals and birds away from any obvious point source of pollution. contacting or consuming the water. Thus different factors can influence many parts of the river Sites are sampled twice a year (autumn and spring) environment. Biological monitoring can be a valuable using the rapid bioassessment technique. This involves tool to measure the overall effect of all these collecting two types of biological samples where influences. possible. ◆ Kick samples for riffle habitat Invertebrate analysis techniques To conduct kick samples, the stream bed is disturbed Biological data can be analysed in a number of by the sampler’s feet to dislodge animals which are ways – from using simple biotic indices through to swept into a net by the current. Samples are taken more complex statistical and modelling procedures. 2 A combination of analytical and interpretative several mathematical models. These models are being measures gives far more reliable results than any refined in 2000. measure on its own. Each model uses reference data collected under the MRHI from a single aquatic habitat from either a Number of families single season (autumn or spring) or from the two The number of invertebrate families found in streams seasons combined (Coysh et al. 2000). can give a reasonable representation of the health of a stream, though it is too great a simplification of data AUSRIVAS predicts the macroinvertebrates which to be adequate on its own. Lack of suitable habitat or should be present in specific stream habitats under the presence of various pollutants can cause a reference conditions. It does this by comparing a test reduction in the number of families present. This site with a group of reference sites which are as free assessment method complements SIGNAL (see as possible of environmental impacts but have similar below) which tends to underestimate toxic effects. physical and chemical characteristics to those found at the test site. SIGNAL One of the products of AUSRIVAS is a list of the aquatic macroinvertebrate families and the probability This biotic index uses families of aquatic invertebrates of each family being found at a test site if there were that have been awarded sensitivity scores according no environmental impacts. By comparing the totalled to their tolerance or intolerance to various pollutants. probabilities of predicted families and the number of The index is calculated by totalling these scores and families actually found, a ratio can be calculated for dividing by the number of families present. A single each test site. This ratio is expressed as the observed value between one and 10 is produced, reflecting the number of families/expected number of families (the degree of water pollution – high quality sites have O/E index). high SIGNAL scores (Chessman 1995) (table 1). While SIGNAL is particularly good for assessing The value of the O/E index can range from a minimum water quality problems such as salinisation and of zero (none of the expected families were found at organic pollution, its usefulness for toxic impacts and the site) to around one (all of the families which were other types of disturbance is uncertain. expected were found). It is also possible to derive a score of greater than one, if more families were found at the site than were predicted by the model. A site Table 1: Key to SIGNAL scores with a score greater than one might be an SIGNAL score Water quality unexpectedly diverse location, or the score may indicate mild nutrient enrichment by organic pollution, >7 Excellent 6-7 Clean water allowing additional macroinvertebrates to colonise. 5-6 Doubtful, mild pollution The O/E scores derived from the model can then be 4-5 Moderate pollution compared to bands representing different levels of <4 Severe pollution biological condition, as recommended under the MRHI (table 2). This allows an assessment of the AUSRIVAS level of impact on the site to be made and One of the main aims of the National River Health characterisation of the general health of the part of Program was the development of predictive models the river that was sampled. which could be used to assess river health. As a result, At this stage of its development, it appears that the Co-operative Research Centre for Freshwater AUSRIVAS is more sensitive to changes in habitat Ecology has developed the Australian Rivers than to changes in water quality.