- Some of the most pristine estuaries in the Australia are found in southern Tasmania (e.g. Bathurst Harbour and New River Lagoon within the south-west World Heritage Area).
- Tasmanian estuaries are diverse, mainly due to extreme differences in wave energy and rainfall between the west and east coasts, a greater tidal range on the north coast and variation in local geomorphology.
- The main cities of Hobart and Launceston are situated on the shores of the Derwent and Tamar estuaries, respectively. Both estuaries have been severely modified by urban, industrial and agricultural developments yet have high levels of biodiversity and endemism.
- As an island State, many larger estuaries are important for shipping. Many mainland visitors arrive by ship in the Mersey estuary.
- Estuaries, such as the Huon estuary and D'Entrecasteaux Channel are economically important as marine farming areas and for recreational activities.
- There is a need for management coordination. This could be achieved based on a synthesis of current legislation and development of an estuarine habitat management plan.
- A range of factors affect estuarine health in Tasmania; management needs to recognise that these factors will impact differently on the different physical types of estuaries.
- We need to provide communities with the tools to monitor estuaries and, given the diversity of estuarine types, directions as to what to monitor.
- We need better mechanisms to provide environmental information about estuaries through to a local level, building understanding and better management.
- Management decisions need greater emphasis in on-ground action.
The management of Tasmanian estuaries is primarily the responsibility of the Department of Primary Industries, Water and Environment, which provides leadership in the sustainable development and conservation of Tasmania's resources by playing a central role in resource management, industry development, environment protection and conservation of natural and cultural heritage. Various agencies within the Department are responsible for the planning and management of the aquatic and terrestrial estuarine environment.
State legislation relating to estuaries management:
- Living Marine Resources Management Act 1995 (Tas)
- National Parks and Wildlife Act 1970 (Tas)
- Environmental Management and Pollution Control Act 1994 (Tas)
- Land Use Planning and Approvals Act 1993 (Tas)
- Water Management Act 1999 (Tas)
The State Coastal Policy 1996 has a central objective of sustainable development of the coastal zone. All activities, uses and developments which may impact on the coast, are required to meet the objectives of the State Coastal Policy. The three main guiding principles of the policy are:
- protection of natural and cultural values of the coast;
- use and development of the coast in a sustainable manner; and
- integrated management and protection of the coastal zone is a shared responsibility.
Under the State Policy on Water Quality Management 1997, protected environmental values must be set for all Tasmanian surface waters, including estuarine and coastal waters. Protected environmental values (the current uses and values of the waterways) have been documented in a consultative process that involved all interested industry and community groups. As a result of the consultation, water quality objectives, to achieve all protected environmental values nominated for an estuary have been set.
There are a number of community conservation and rehabilitation initiatives in and around Tasmanian estuaries. Many of these community initiatives have been established under Tasmanian Landcare Association programs (e.g. Coastcare, Waterwatch, Rivercare, Bushcare). The activities undertaken by these groups include water quality monitoring, weed eradication, re-establishment of native flora and fauna, catchment and foreshore management, and the preparation of educational materials. Over 30 community groups provide input to and are linked through the Derwent Estuary Program (a joint Commonwealth, State and Local Government initiative to restore and protect the Derwent Estuary). The Huon Healthy Rivers Project is an integrated catchment management program involving school and community groups, plus local forestry and aquaculture industries, in water quality monitoring and Landcare activities. On the north coast, Five Rivers Waterwatch is a community based water quality monitoring group covering the Rubicon (Port Sorell), Mersey, Don, Forth and Leven Rivers.
Management priorities for Tasmanian estuaries are to ensure that all activities meet the sustainable development objectives of the Resources Management and Planning System. The State Policy on Water Quality Management and the State Coastal Policy aim to meet these objectives through the establishment of protected environmental values and water quality objectives, and by defining core principles that guide all activities affecting the coastal zone.
Of Tasmania's non-pristine estuaries, many are degraded due to agriculture, forestry and urban development. Sewage, run-off and industrial pollution contribute to reduced water quality in many urban estuaries (e.g. Derwent and Tamar Rivers). Nutrient and sediment loads have increased through agriculture and land clearing, particularly in estuaries in the north-east and north-west of the State. Mining has had a significant impact on some estuaries (e.g. Macquarie Harbour-heavy metals-and in the Boobyalla and Ringarooma estuaries-siltation). In estuaries with upstream hydroelectric dams or irrigation, maintenance of environmental flows is an issue.
The presence of introduced marine pests is a significant issue in many Tasmanian estuaries. Introduced pests (e.g. toxic dinoflagellates (Gymnodinium catenatum), Northern Pacific seastars (Asterias amurensis) and New Zealand screwshells (Maoricolpus roseus) in the D'Entrecasteaux Channel, Derwent and Huon Rivers; rice grass (Spartina anglica) in many estuaries, particularly the Tamar River and Port Sorell) can threaten the ecological integrity of estuaries by altering habitat, outcompeting and preying on local species, or causing shellfish closures.
Resource allocation is a major issue in some Tasmanian estuaries. Commercial and recreational fisheries, marine farms and other coastal developments all compete for resources. Some estuaries provide a cultural and historical centre for coastal communities and support non-extractive uses such as boating, swimming and aesthetic values. Balancing these uses with conservation of estuarine habitat is a significant challenge for estuary managers.
North coast estuaries, from Cape Grim to Cape Portland are characterised by seasonal rainfall with land uses that include agriculture, forestry, urban and industrial developments. These estuaries are generally modified and mostly wave- or tide-dominated. The Tamar estuary has extremely high plant, invertebrate and fish diversity.
The estuaries on the east coast from Cape Portland to Maria Island are subject to low rainfall. Land use includes agriculture and forestry. Modified estuaries are largely wave-dominated. The region also contains a large number of coastal lagoons.
The estuaries from Maria Island to Southport are influenced by seasonal rainfall, often with very dry summers. This region has a convoluted coastline with many protected embayments. The estuaries have high levels of animal and plant endemism. Land use includes agriculture, forestry, urban and industrial developments. The estuaries are generally modified, and include both wave- and tide-dominated systems.
South and west coast
The south and west coast from Southport to Cape Grim has high rainfall. Much of the coastline is exposed to extremely high wave energy. All of the south-west coast is in national parks with grazing occurring in catchments further north on the west coast. These estuaries are predominantly near-pristine with tannin-rich waters. Unique biotic communities occur in Bathurst Harbour.
Bass Strait islands
The predominantly wave-dominated estuaries of King Island, Flinders Island and Cape Barren Island are mostly in near-pristine condition. Rainfall is seasonal and the land is primarily used for grazing.
For further information about the Australia-wide assessment, please contact: National Land and Water Resources Audit Phone: 02 6263 6035 Email: firstname.lastname@example.org
CRC Coastal Zone, Estuary and Waterway Management
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