Conservation and Environment

River Health and Ecology

Rivers are an important component of the ecosystem providing habitat for many fish, aquatic invertebrates, birds, amphibians and reptiles. The health or condition of rivers and associated vegetation communities can be negatively impacted by increasing salinity, sedimentation, pollution, removal and destruction of instream habitat, and altered flow regimes. These threatening processes can impact on the fauna directly, through toxic effects, or indirectly, including by the loss of suitable breeding, sheltering and feeding sites and isolation of populations due to loss of water connectivity between floodplains and river systems. These impacts and threats can result in a loss of aquatic biodiversity from these systems. Restoration of aquatic habitats aims to return these systems back to a natural state and minimise threats. By measuring the condition of aquatic systems we can establish the severity of detrimental impacts and threats and develop strategies for restoration efforts.

Key projects (with details below)

Native Fish Guide for Coastal Victoria Linking Salt Wedge Dynamics of Estuaries to Fish Productivity - Gippsland Lakes River Health and Hydro-electricity Operations Sustainable Rivers Audit and Southern Basins Program - Macroinvertebrates An Education Strategy for Fishways The Flood Pulse Concept and Rivers with Variable Flow Regimes

Key projects (in other themes)

Survey for Threatened Alpine Stoneflies after the 2006-2007 Fires (Bushfire Recovery) Rehabilitation of Instream Habitat for Trout Cod at Seven Creeks (Threatened Species and Communities) Movement Patterns of River Blackfish (Mapping and Measuring Biodiversity)

Native Fish Guide for Coastal Victoria Victoria’s coastal aquatic systems encompass all rivers, estuaries and wetlands south of the Great Dividing Range. These environments play a vital role in the social, economic and environmental health of the state. To improve the management of native fish, large decapod crustaceans and large bivalve molluscs in these systems, a suite of resources have recently been released. These include a published management guide, an on-line decision-support tool, and educational materials. These resources have been designed to assist local natural resource managers with various aspects of fish management, and to increase awareness and understanding of fish ecology, habitat needs and impacts of threatening processes. The development of these products was funded by the National Heritage Trust. The ‘Guide to the Management of Native Fish: Victorian Coastal Rivers and Wetlands’ provides information on fish biology and habitat requirements for native fish that occur in the coastal catchments of Glenelg Hopkins, Corangamite, Port Phillip, Western Port, West Gippsland and East Gippsland. It outlines how various threats to river health may impact on particular species and will link closely with the existing implementation of regional River Health Strategies. Broad recommendations are provided on how to set priorities and make informed decisions about native fish management. FAST (Fish Assessment Support Tool) is a web-based decision-support tool to help managers to more effectively consider fish requirements within existing and future river protection and rehabilitation programs. The educational materials include 15 stickers featuring 10 significant freshwater and estuarine fish species, and five important habitats. There are also six fact sheets outlining key habitat features and issues important to coastal native fish. Three posters highlight over 50 important freshwater, estuarine fish and crayfish species and include distributional maps, information on altitudinal zones, habitats, recreational and cultural values, threatened status, spawning calendars, and up and downstream movement of larvae, juveniles and adults. The crayfish poster also includes some key features to distinguish terrestrial, aquatic and semi-aquatic crays. For further information and copies of these products contact Pam.Clunie@dse.vic.gov.au For information on FAST contact Stephen.Saddlier@dse.vic.gov.au The following fact sheets provide information on six important coastal habitats: Native Fish in Coastal Victoria - Aquatic Vegetation (PDF - 986 KB) Native Fish in Coastal Victoria - Flow Regimes (PDF - 960 KB) Native Fish in Coastal Victoria - Salt Wedges (PDF - 1.1 MB) Native Fish in Coastal Victoria - Structural Woody Habitat (PDF - 1.2 MB) Native Fish in Coastal Victoria - Water Quality (PDF - 1.1 MB) Native Fish in Coastal Victoria - Wetlands (PDF - 1.1 MB) Page Top
Linking Salt Wedge Dynamics of Estuaries to Fish Productivity - Gippsland Lakes The freshwater needs of Australia’s estuaries are poorly understood. How freshwater flows through an estuarine system influences the productivity and dispersion of salt wedges, which are important nurseries for fish larvae. Salt wedges occur at the freshwater-saltwater interface where freshwater flows as a layer over the saltwater ‘wedge’. Maintaining and managing the health of Victoria’s estuaries depends partly on understanding their freshwater requirements and being able to make informed decisions on the allocation of water to them. This study aims to contribute to this understanding, by investigating salt wedge dynamics in the Gippsland Lakes, Victoria. Results from this study will have applications in managing the delivery of freshwater to support fish production within estuaries across Victoria. Information collected on the early life history of fish will be integrated with hydrological modelling to determine links among freshwater flows, salt wedge dynamics and fish production. Field sampling began just after substantial natural flooding of the Lakes in June 2007 and focussed on sampling fish eggs and larvae around salt wedges. ‘Hot spots’ for fish eggs and larvae were found in the vicinity of the salt wedge within the Mitchell, Tambo and Nicholson Rivers, with most bream larvae and eggs found immediately downstream of the salt wedge. To better describe the dynamics of this salt wedge, and improve the ability to model changes in the salt wedge from freshwater flows, the bathymetry of the these rivers is now being mapped. Aspects of water quality such as salinity, temperature and water level are also being recorded. During the current spawning season (September to December 2008) eggs and larvae will be sampled at different depths within the water column and acoustic telemetry will be used to study the movements of spawning fish. This information will provide further information on where, and at what depth, spawning is occurring. This study is being funded through an Australian Research Council Linkage Grant, and is being run in partnership with the Department of Primary Industries, University of Melbourne, Gippsland Coastal Board, West Gippsland Catchment Management Authority, and the Nicholson Angling Club. For more information contact Jeremy.S.Hindell@dse.vic.gov.au Page Top
River Health and Hydro-electricity Operations Over the past 10 years a monitoring program has been in place to assist AGL Hydro (formerly Southern Hydro) in managing potential environmental impacts from their dam desilting operations. AGL Hydro operates the Kiewa Hydro-electric Scheme in north-east Victoria and annually desilts two storage dams on the Kiewa River system to ensure storage capacity is maintained. In 1997 the desilting timing was changed from occurring during low river flows (summer and autumn) to during high flow periods (late winter and early spring) to minimise the impact of released silt loads on the river biota. Since then, the health of the river downstream of the desilting operation has been regularly monitored. The composition of aquatic macroinvertebrate communities is being used as the principal indicator of river health, using a mathematical model (developed during the project) that predicts which species should be present. The model is termed KieRivAS (Kiewa River Assessment System) and is similar to the Australian River Assessment System. Populations of the Two-spined Blackfish Gadopsis bispinsosus are also surveyed to provide additional information on whether the desilting is having an impact on resident biota. Analysis of the data indicates that the desilting is not adversely affecting macroinvertebrate and fish populations. It appears that although the Kiewa River system has been considered to be in poor health for several years, this is due to drought conditions (low rainfall leading to low flows). The length of time over which this data has been collected provides a unique insight into the natural variations in environmental conditions and aquatic fauna population changes that occur over many years within a river system. It is important to be able to identify such changes so that the causes can be correctly identified. Data is presented annually to AGL Hydro and a desilting working group comprising members from Catchment Management Authorities, Parks Victoria, the Environmental Protection Authority and the Department of Primary Industries. For further information contact David.Bryant@dse.vic.gov.au Page Top	. .
Sustainable Rivers Audit and Southern Basins Program - Macroinvertebrates For several years the Victorian Environment Protection Authority has commissioned ARI to undertake macroinvertebrate surveys as part of the Sustainable Rivers Audit and Southern Basins programs. These programs are designed to measure the health of river systems in the Murray-Darling Basin and south of the Great Dividing Range. Both programs aim to: determine the ecological condition and health of the river systems; provide a better insight into the variability of river health indicators across the river systems; help detect trends in river health over time; trigger changes to natural resource management by providing a more comprehensive picture of river health than is currently available. Macroinvertebrates are monitored to provide a measure of river health - some are tolerant to pollution and some are sensitive. Sampling is carried out in consecutive spring and autumn seasons using standard Rapid BioAssessment Protocols targeting both fast flowing and shallow (riffle) and slow flowing (edge) habitats so as to maximise the macroinvertebrate diversity recorded. The catchments of Otways, Portland and Werribee are currently being surveyed. For further information contact David.Bryant@dse.vic.gov.au Page Top	. .
An Education Strategy for Fishways Forty-two species of native freshwater fish have been described for Victoria, all of which need to travel varying distances within their habitat. Man-made structures such as dams and weirs, can inhibit or prevent fish from accessing new foraging areas, dispersing into new habitats and moving between breeding and spawning grounds, thereby restricting population growth. Providing fish with a way to pass over instream barriers has been recognised as an important process for maintaining and restoring native fish populations and river health. Structures for assisting fish movement over barriers, or ‘fishways’, are currently being constructed across Victoria as part of the State Fishway Program. To date, over 50 fishways have been installed, opening fish passage to at least 4500 km of riverine habitat. To help increase public awareness of the existence of fishways and the importance of fish movement within a river, a fishways website has been developed with funding assistance from the Natural Heritage Trust. The website, also designed to be a resource for management authorities, contains information on why fish need to move, fish species found in Victoria’s 39 river basins, fish species migration times, the variety of barriers to fish movement and types of fishways currently in use. For further information contact Jarod.Lyon@dse.vic.gov.au Page Top	.
The Flood Pulse Concept and Rivers with Variable Flow Regimes Much of our current knowledge on how food webs function in floodplain rivers is derived from the Flood Pulse Concept, which suggests that pulses of water flow (whether it be within-channel or floodplain inundation) coupled with high temperatures, provide optimum conditions for biological production. This model was developed based on tropical river floodplains within which flood pulses are often predictable in terms of seasonal occurrence and duration. There is, however, a lack of evidence that the model is directly applicable to the more variable temperate floodplain systems of Australia. Since 2003 the lower Ovens River, an unregulated floodplain river in north-east Victoria, has been the subject of a study examining how river channel food webs respond to flow pulses of differing magnitudes, timing and duration. To measure the responses from the lower end of the food web, levels of organic carbon, as well as its source, are being monitored in the river channel. Fish production (growth), at the upper end of the food web, is being measured by monitoring growth patterns of larval and juvenile Australian Smelt (Retropinna semoni). Information will be collected over a number of years to allow a variety of flow and temperature conditions to be compared. Investigating the link between organic matter transport, fish production and various types of flow events will give a much needed insight into this process while testing the suitability of the Flood Pulse Concept as a management tool. The information collected will contribute to the management of river systems, in particular on aspects of controlled water releases throughout the southern Murray-Darling basin. This study is being conducted in collaboration with the University of Western Australia. For more information contact: Zeb.Tonkin@dse.vic.gov.au Page Top	.