Sponge below tannin waters
by Heidi Dungey
The Ninepin Point Marine Nature Reserve occupies 731.8 hectares in the D’Entrecasteaux Channel near the mouth of the Huon River.
The reserve protects a unique assemblage of plants and animals in an unusual aquatic environment where cold, nutrient-rich sea water from the southern ocean is overlaid with tannin-rich freshwater leached from the decaying organic matter in the Huon River catchment.
The depth of the tannin layer at Ninepin Point varies throughout the year depending on rainfall. It may be almost absent during dry summer periods but can extend down to 12 metres or more after heavy rainfall and run off from the catchment resulting in near zero visibility. Water temperatures range from 8°C to 20°C.
The resulting tea-coloured water at Ninepin Point reduces light levels on the local reefs, allowing the growth of a fascinating array of invertebrates, fish and red seaweeds, normally found only in much deeper water on Tasmania's east coast. Conditions are ideal for the growth of red algae, resulting in an unusually high diversity of red algal species. The reserve also includes some beach and foreshore areas in addition to the marine environments.
The Ninepin Point Marine Nature Reserve was first declared in 1991 as a nature reserve under the National Parks and Wildlife Act 1970. This reserve classification was carried forward into the Nature Conservation Act 2002. A nature reserve provides for the conservation of the natural biological and geological diversity of the area and the conservation of the natural values of that area that are unique, important or have representative value.
The reserve area was significantly extended on 9 December 2009. The extension will greatly increase its conservation significance by providing a larger area for the protection of the unique natural values of the region. For example the deep reef habitat and invertebrate assemblages in the Arch Rock area and sheltered reef and sediments with their associated flora and fauna have been given greater protection.
Ninepin Point Marine Nature Reserve is also reserved as a marine nature reserve under the Living Marine Resources Management Act 1995
by virtue of Rule 3 of the Fisheries Rules 1999.
These Rules establish ‘no take’ fishing restrictions
within the reserve.
The reserve is jointly managed by Tasmania Parks and Wildlife Service and Marine Resources.