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Government of Western Australia Department of Water and Environmental Regulation
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Finding new water resources, including Royalties for Regions-funded programs and other drilling programs to explore resources across the state.

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Click here to apply for rebates and grants for farmers, pastoralists and rural communities to improve local water supplies and for information about assistance to help farmers access water during dry seasons.

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Find out who is eligible to trade water entitlements and how applications are assessed. Click here to identify potential trading partners from the Water Register.

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Information on the state’s groundwater resources, locations, investigations, aquifer recharge and sustainable management of water resources, including an overview of state groundwater investigations.

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Rivers and estuaries and their importance including information on monitoring and assessing waterways, protecting, understanding, planning, restoring, and risks and threats.

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There are 166 estuaries in Western Australia as established through the National Land and Water Resources Audit (NLWRA) 2000, where an estuary is defined as

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Information on the department’s role in relation to the shale and tight gas industry.

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Macroalgae

Macroalgae, like seagrasses, typically occur in shallow water where there is suitable light for growth. Macroalgae generally attach themselves to structures such as rock, wood or other plants. Some species, particularly filamentous species, are free-floating and move around with the currents. Macroalgae are important in aquatic ecosystems as a food source and habitat to invertebrates, fish and birds. 

Macroalgae grow rapidly in response to nutrient enrichment. Land clearing and increased drainage for agriculture have been among the main causes of pollution in the drains and streams that flow into estuaries. Fertilised lawns and septic tanks are also a problem. We generally notice more macroalgae in summer when there is more light, longer days and warmer temperatures, which are ideal conditions for macroalgae and other plants to grow.   Summer storms can result in excessive macroalgal growth as more nutrients than normal wash into the estuary.Macroalgae in a lake

Macroalgal growth, when excessive, is known as a macroalgal bloom. These events are considered a nuisance as they can disrupt the growth of other plants in the estuary, such as seagrass.

Shading of seagrass can result in fewer flowers being produced (lower reproductive success), slower growth rates and ultimately the death of whole plants. The loss of seagrass and macroalgae is followed by decomposition, which consumes oxygen from the water column. Over a wider area this is undesirable for fish and invertebrates and can result in fish kill events.

A good example is the Peel-Harvey estuary which, in the 1980s, became choked by dense growths of green algae (Chaetomorpha, Enteromorphaand Cladophora). The bloom was persistent, and so severe and unpleasant, that a 'weed' harvesting scheme had to be introduced to remove accumulations which were rotting on the shore.Macoalgae in Waylen Bay, Swan River 2010

The Department of Water as part of its estuary management role is working to better understand the timing and triggers of these nuisance algal blooms, and their impact on the affected systems as a whole.

The frequency and severity of algal blooms is an indication of estuary ecological health, and an important consideration in the development of Estuary Management Plans (EMPs) and Water Quality Improvement Plans (WQIPs) developed by the department.

Page last updated - 17 Mar 2015
Related publications

Riverscience #20 Macrophytes and macroalgae in the Swan-Canning estuary

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The Department of Water and Environmental Regulation was established by the Government of Western Australia on 1 July 2017. It is a result of the amalgamation of the Department of Environment Regulation, Department of Water and the Office of the Environmental Protection Authority. This website/publication may contain references to previous government departments and programs. Please contact the Department of Water and Environmental Regulation to clarify any specific information.

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