Estuarine Health

The concept of health has recently been used to signify whether environments are natural (healthy) or highly polluted and disturbed (unhealthy). Thus the term "unhealthy estuary" does not imply that it is full of pathogens and is dangerous for people to swim in.

Importance of monitoring estuarine health

Estuaries are often used for recreational purposes.

Most of Australia's major cities are located around estuaries, and many of our major estuaries have cities located on them. Many Australians participate in fishing and other water sports based on estuaries. Consequently, estuarine health has a high profile in Australia.

Australia has extensive environmental laws to protect its estuaries from pollution. Many industries and municipal councils spend large sums of money to avoid or minimise estuarine pollution. However, we have no way to assess whether the overall health of our estuaries is improving, being maintained or deteriorating.

Estuarine health assessments are required to provide regional reports on the state of the environment, assess whether water quality is being maintained or improved by local and regional environmental programs, and to quantify environmental changes caused by pollution and habitat modifications. Primarily an estuarine health monitoring program would be of benefit to national, state and local authorities responsible for environmental protection and nature conservation. However, it will have widespread secondary benefit through improved management of estuaries, which are an important commercial and recreational resource for many Australians.

In the USA, biotic indices are frequently used to assess estuarine health. These indices usually incorporate knowledge of the animals biology (trophic levels, sediment depths at which different species occur, etc.). Knowledge of Australian benthic animals is not sufficient to utilise such indices. Consequently, we propose using the composition of the benthic community to assess environmental health.

Monitoring approaches

The plants and animals present in an estuarine community are dependent on the physical and chemical environment. Management of the estuary to maintain a healthy environment requires maintaining the physical and chemical environments in the range normally experienced by the natural community. A monitoring program can therefore look directly at the animals (biomonitoring) to ensure a normal community is being maintained, or the monitoring program can look at the physical and chemical variables to ensure they stay in the range required by the community.