Darwin Harbour Region Report Cards 2010
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Darwin Harbour Region Report Cards 2010 www.greeningnt.nt.gov.au This report was prepared by John Drewry, Peter Dostine, Julia Fortune, Matt Majid, Julia Schult, and Gisela Lamche. Aquatic Health Unit. Department of Natural Resources, Environment, The Arts and Sport. Palmerston NT 0831. Website: www.nt.gov.au/nreta/water/aquatic/index.html This report can be cited as: Drewry, J., Dostine, P.L., Fortune, J., Majid, M., Schult, J., Lamche, G. 2010. Darwin Harbour Region Report Cards 2010. Department of Natural Resources, Environment, The Arts and Sport. Report No 25/2010D. Palmerston, NT, Australia. Disclaimer: The information contained in this report comprises general statements based on scientific research and monitoring. The reader is advised that some information may be unavailable, incomplete or unable to be applied in areas outside the Darwin Harbour region. Information may be superseded by future scientific studies, new technology and/or industry practices. © 2010 Department of Natural Resources, Environment, The Arts and Sport. Copyright protects this publication. It may be reproduced for study, research or training purposes subject to the inclusion of an acknowledgement of the source and no commercial use or sale. Annual publication ISSN 1838-4625 (Print) ISSN 1838-4633 (Online) Report No 25/2010D Front cover photos The Indo-Pacific humpback dolphin (Sousa chinensis) is commonly found in Darwin Harbour. Photo: Carol Palmer. Beach stone-curlew (Esacus neglectus). A shy resident of reefs, beaches and coastal mudflats of northern and eastern Australia. Photo: Mat and Cathy Gilfedder. An undescribed sponge species of the genus Haliclona. It is restricted to the intertidal area. Found only at East Point, Channel Island and Cullen Bay. Photo: Belinda Glasby. Northern trout gudgeon (Mogurnda mogurnda) occurs in Rapid Creek. Photo: Dave Wilson. Back cover photos This species of the sponge genus Petrosia, is common in the area of Elizabeth River estuary. Photo: Belinda Glasby. Sunset at Nightcliff, Darwin. Photo: Nolan Caldwell. Rapid Creek is the largest freshwater stream in the Darwin area. Darwin HarbourDarwin Harbour Advisory Advisory Committee Committee Acknowledgements The project was supported by the Darwin Harbour Advisory Committee. We thank many people who contributed photographs. Information was kindly supplied by Belinda Glasby (sponges) and Richard Willan (cyanobacteria and algae). We thank Larrakia Nation. Data in this report were obtained from projects funded by the Northern Territory Government and the Australian Government. Symbols are courtesy of the Integration and Application Network (ian.umces.edu/ symbols/), University of Maryland Center for Environmental Science, USA. Several conceptual diagrams were adapted from base diagrams from the Integration and Application Network. ii Message from the Chair of the Darwin Harbour Advisory Committee The Darwin Harbour Advisory Committee (DHAC), in partnership with the Aquatic Health Unit of the Department of Natural Resources, Environment, The Arts and Sport, is very pleased to present the second annual Darwin Harbour Region Report Cards 2010. This annual snapshot of the Harbour’s health is critical to assess the condition of the Harbour and highlight any changes, potential impacts and cumulative effects of development at an early stage. In future years there will be increased pressure on the Harbour environment from increasing population and increasing development and industry. We are fortunate that monitoring is well underway and baseline data of areas that have been relatively unimpacted by human activity are being collected. This provides an important foundation for future decision making about the use of the region. The new report card for the West Arm region on the Cox Peninsula is an excellent addition for this purpose. As the Chair of DHAC I look forward to, and encourage, continual improvement of these Report Cards and this year is no exception. I wish to acknowledge the hard work and commitment of the Aquatic Health Unit, Department of Natural Resources, Environment, The Arts and Sport in presenting their data in a transparent and user friendly way to meet the significant public interest in our beautiful Harbour. The Darwin Harbour Strategy prepared by DHAC and endorsed by the Northern Territory Government in June this year is a comprehensive guide for the responsible stewardship and sustainable development of the Darwin Harbour region. The Darwin Harbour Region Report Cards are an important component of the Darwin Harbour Strategy in a practical way which provides government and the public with an annual snapshot of the state of the Harbour. Bill Stuchbery Chair Darwin Harbour Advisory Committee iii View across Darwin CBD and city. The Charles Darwin National Park, and the East Arm Port are in the background. Photo: Tourism NT iv Contents Darwin Harbour Region .................................................................................................1 Summary ....................................................................................................................2 The Report Cards .......................................................................................................3 Our harbour, our life, our future ..................................................................................3 Culture – land and sea country ...................................................................................4 The Aquatic Health Unit ..............................................................................................4 Understanding water quality and pollution sources....................................................5 Introduction .................................................................................................................6 Estuarine monitoring sites, pollution sources, and ecology of Darwin Harbour ..........7 Estuary processes in the wet and dry seasons ..........................................................8 Formation of cyanobacteria blooms in Darwin Harbour and beach areas ................10 Monitoring sites for beach areas, tidal creeks and mixing zone areas .....................11 Darwin Harbour water classifications ........................................................................13 Key indicators for estuarine and freshwater quality ..................................................13 Interpreting the Report Cards .....................................................................................15 Introduction ...............................................................................................................16 Interpreting the Report Cards ...................................................................................17 Darwin Harbour Beaches Report Card 2010 ..............................................................21 Darwin Harbour Report Card 2010 ..............................................................................29 Darwin-Palmerston and Estuary Report Card 2010 ...................................................33 Elizabeth River and Estuary Report Card 2010 ..........................................................39 Blackmore River and Estuary Report Card 2010 .......................................................45 Shoal Bay and Buffalo Creek Report Card 2010 ........................................................51 West Arm and Woods Inlet Report Card 2010 ............................................................59 Rapid Creek Report Card 2010 ....................................................................................63 Further reading ............................................................................................................67 Glossary .......................................................................................................................67 v The Indo-Pacific humpback dolphin (Sousa chinensis) is known as a coastal or near-shore dolphin and is typically found in small populations inhabiting shallow coastal and estuarine waters, usually within about 10 km of land, in water less than 15 m deep and within about 20 km from the nearest river mouth. This dolphin is vulnerable to habitat degradation, boat strikes, pollution and increased shipping traffic. Estimates of population size in local areas along the Queensland coast indicate that populations are notably small making them particularly vulnerable to human-induced disturbances on coastal ecosystems. The Coastal Dolphin Research Project is currently undertaking baseline research on this species in Darwin Harbour along with the two other species of coastal dolphins: the endemic Australian snubfin (Orcaella heinsohni) and the Indo-Pacific bottlenose (Tursiops aduncus). This photo of the Indo-Pacific humpback dolphin was taken in the Howard River area. Photo: Carol Palmer vi Darwin Harbour region Aerial view of creek. Photo: Jeremy Freeman Mindil Beach Nymphaea violacea in Korebum Lagoon. Nymphaea is known as dambilinggwa to Larrakia people. Photo: Gisela Lamche 1 Darwin Harbour Region Summary Water quality results The Report Cards provide a snapshot of stream water quality from sites monitored in 2009, and water quality of estuarine sites monitored quarterly in late 2008 and 2009. Water quality at Darwin beaches was monitored in 2010. Water quality in outer Darwin Harbour, Elizabeth River, Darwin-Palmerston regions and outer Shoal Bay is in excellent condition. However, water quality at Buffalo Creek sites is in very poor condition. Water quality