Department of Sustainability, Environment, Water, Population and Communities
About the document
An Ecological Character Description describes the ecological character of a wetland at the time of its listing as a Wetland of International Importance. The Ecological Character Description is a fundamental management tool for site managers, forming the basis of management planning and action as well as including guidance on site monitoring requirements to detect changes in the ecological character of the site.
Elizabeth and Middleton Reefs are a pair of isolated oceanic platform reefs separated from one another by 45 km of deep oceanic waters. Elizabeth and Middleton Reefs are located in the northern Tasman Sea, 630 km east of Coffs Harbour (NSW); 690 km east-southeast of Brisbane (Queensland); and 150 km north of Lord Howe Island.
The two reefs are of similar size and shape with Elizabeth Reef measuring 8.2 km by 5.5 km and Middleton Reef slightly larger at 8.9 km by 6.3 km. The reefs are largely awash, with only two small sand cays being emergent at high tide. The largest cay, Elizabeth Island, found on Elizabeth Reef, measures around 400m in length and up to 400m in width. The smaller cay, known as The Sound and located on Middleton Reef, measures 100m by 70m. Both barely emerge 1m above the high water level. At low tides much of the reef flat is exposed by the receding waters. Elizabeth and Middleton Reefs are physically and biologically similar to one another and both contain unique assemblages of tropical, temperate, endemic and cosmopolitan species.
Elizabeth and Middleton Reefs are unique in that they represent the southern-most platform reefs in the world. Despite their high latitude, both reefs display a rich and diverse marine flora and fauna, aided by their location in an area where tropical and temperate ocean currents meet. The Reefs support diverse marine fauna and coral reef communities that are distinct from others in Australia's East Marine region. These include uncommon and undescribed fish, several endemic molluscs and several species at or near their northern or southern limits of distribution. They support healthy stocks of two apex predators – the Galapagos Reef Shark (Carcharhinus galapagensis) and the Black Cod (Epinephelus daemelii). The reefs offer protection for several other species of commercially valuable pelagic and demersal fish, and many species of significance, including numbers of migratory marine turtles and seabirds. They provide the only habitat for many of these species in a vast area of deep ocean.
The ecological character of a wetland is the sum of all the components, processes and services of that wetland. Ecosystem components are physical, chemical and biological parts of a wetland, from large-scale to very small-scale (e.g. habitat, species and genes). Ecosystem processes are the dynamic forces within an ecosystem. They include all those processes that occur between organisms and within and between populations and communities, including interactions with the non-living environment, that result in existing ecosystems and bring about changes in ecosystems over time. Ecosystem services are the benefits that people receive from ecosystems.
The Ecological Character Description identifies those ecological components, processes and ecosystem services considered most critical for sustaining the character at the site. In particular, the services provided at the site are:
- It is representative of a unique ecosystem in the bioregion: southern-most open-ocean coral reef platform in the world
- It supports threatened species: Green turtle (Chelonia mydas)
- It supports regionally high species diversity:
- fish (see also Black Cod below)
- coral communities;
- molluscs, and
- It supports animal taxa at a vulnerable or critical stage of their lifecycle: Galapagos Shark (Carcharinus galapagensis), and
- It supports the last known large population of Black Cod (Epinephelus daemelii).
The description also identifies limits of acceptable change which describe the range of variation which key aspects of the ecology of the site can vary without representing a change in the ecological character. Limits of acceptable change for the Elizabeth and Middleton Reefs have been proposed for most critical components, processes and benefits and services based on existing data.
The Ecological Character Description also describes the current Ramsar listing criteria met by the site, the key threats and knowledge gaps for Elizabeth and Middleton reefs. Recommended monitoring needs and communication messages are also provided. There may be differences in the type of information contained in this Ecological Character Description to those of other Ramsar Wetlands as this Ecological Character Description preceded agreement by the Natural Resources Management Ministerial Council to the National Framework and Guidance for Describing the Ecological Character of Australian Wetlands (Department of the Environment, Water, Heritage and the Arts, 2008).
Further information on what Ecological Character Descriptions are and how critical components, processes and services are identified is available in the National Framework and Guidance for Describing the Ecological Character of Australian Ramsar Wetlands – Module 2 of the National Guidelines for Ramsar Wetlands – Implementing the Ramsar Convention in Australia.