South Arm (24549)
Australia, Australasia
Site overview
KBA status: confirmed
Global KBA criteria: D1a
Year of last assessment: 2009
National site name: South Arm
Central coordinates: Latitude: -42.8685, Longitude: 147.5318
System: marine, terrestrial
Elevation (m): 0 to 5
Area of KBA (km2): 52.6133
Protected area coverage (%): 45.09
KBA classification: Global
Legacy site: Yes
Site details
Site description: This IBA is made up of five discrete areas of tidal inlets east of Hobart that together comprise an extensive and diverse wetland system with abundant shorebirds. These are: Ralphs Bay, Mortimer Bay, Calvert's Lagoon, South Arm Neck, Barilla Bay, Orielton Lagoon, the seaward aspect of the causeway in Pitt Water, and Pipe Clay Lagoon in Frederick Henry Bay. The IBA is defined by all areas supporting significant numbers of feeding and roosting Pied Oystercatchers; colour-banding research has shown that individual oystercatchers and migratory shorebirds move regularly among these sites to feed and roost (Birds Tasmania unpubl. data). These are predominantly estuarine mud and sand flats with significant areas of saltmarsh. This system is the southernmost destination for migratory shorebirds in the East Asian-Australasian Flyway.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.
Additional biodiversity: This IBA supports high numbers of migratory shorebirds, including Red-necked Stint regularly above 600, Eastern Curlew counts above 50, Curlew Sandpiper above 200 and Sooty Oystercatcher above 40. The South Arm IBA together with the Marion Bay IBA to the east are part of a network of wetlands which collectively support more than 1% of the global population of Red-necked Stint, but numbers within each individual IBA are below the 1% threshold. Other species which have been infrequently recorded within the IBA include Fairy Tern, Tasmanian Native-hen, Yellow Wattlebird and Striated Fieldwren (Atlas of Australian Birds database). Non-bird biodiversity: Around the rocky shores of Pitt Water and along the Sorell Causeway is the largest concentration of the small endemic seastar Patiriella vivipara, one of the few viviparous sea stars known. The saltmarshes around Barilla Bay provide one of the few recorded Tasmanian localities of the rare Chequered Blue Butterfly.
Other site values: Parts of four small protected areas are included but most of the IBA is private properties, some of which extend to low water mark.
Habitats
Land use: nature conservation and research | not utilised | rangeland/pastureland
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Marine Coastal/Supratidal | 5 | |
| Marine Intertidal | 90 | |
| Marine Neritic | 5 |
Threats
Summary of threats to biodiversity at KBA: Removal of exotic species and greater control of human disturbance would improve this IBA. The marina proposal for Ralphs Bay (Lauderdale) would destroy large feeding and roosting areas used by 700+ Pied Oystercatchers.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Pollution | Agricultural & forestry effluents | Nutrient loads | Ongoing |
| Human intrusions & disturbance | Recreational activities | Ongoing |
Additional information
References: Blake, G., Sharples, C., Bell, P. and van Putten, I. (2001) The Nature Conservation Values of the South East Coast of Tasmania. Reserve Design & Management, Tasmania. Britton, P. and Charlesworth, D. (2005) The 2004 summer and winter wader counts. Tasmanian Bird Report 31: 14-21. DEWHA (2008) Information Sheet on Ramsar Wetlands (RIS). Pitt Water-Orielton Lagoon - 6. http://www.environment.gov.au/water/publications/environmental/wetlands/database/ accessed August 2008. Draft Management Plan for Orielton/Pittwater Ramsar wetlands Park, P. (2004) Summer and winter wader counts, 2002 and 2003. Tasmanian Bird Report 30: 28-41. Rudman, T. (2003) Tasmanian Beach Weed Strategy for marram grass, sea spurge, sea wheatgrass, pyp grass & beach daisy. DPWIE Nature Conservation Branch, Technical Report 03/2, Hobart, Tasmania. Woehler, E. and Park, P. (2006) Inventory of Nationally Important Shorebird Sites in Tasmania. Unpublished report by Birds Tasmania for Birds Australia.
Contributors: Thanks to Eric Woehler as compiler. Thanks also to Priscilla Park, Mel Fazackerley, Lynne Sparrow, Sorell Council and Parks and Wildlife Service, NRM South for assistance with data and other information.