Prince Edward Islands (100995)
South Africa, Africa
Site overview
KBA status: confirmed
Global KBA criteria: A1a, A1b, A1c, A1d, B1, B2, D1a
Year of last assessment: 2024
National site name: Prince Edward Islands
Central coordinates: Latitude: -46.8709, Longitude: 37.7672
System: terrestrial, marine, freshwater
Elevation (m): 0 to 1097
Area of KBA (km2): 338.61693
Protected area coverage (%): 100.00
KBA classification: Global
Legacy site: No
Site details
Site description: The Prince Edward Islands (PEIs) are located in the sub-Antarctic zone of the southern Indian Ocean approximately 1 700 km southeast of the mainland of South Africa and the site is fully protected. The volcanic islands comprise of Prince Edward Island (45 km²) and the larger Marion Island (270 km²). The islands are located on a shallow volcanic plateau that breach the ocean surface. Marion and Prince Edward Island reach 1230 m and 672 metres above sea level respectively, and are separated by a 19 km shallow shelf. The islands emerged ~0.45 million years ago and have since been colonised by a wide range of sub-Antarctic flora and fauna. The dominant easterly-flowing current interacts with the plateau to form large phytoplankton blooms that enrich pelagic communities thousands of kilometres downstream. This is known as the island mass effect. The plateau supports a rich seabed community of more than 500 species and is dominated by bryozoans and tube-building polychaetes. The benthic shrimp Nauticaris marionis thrives here and provides an important food source for fish and seabirds. More than 30 fish species from 13 families occur at the islands, including the commercially important Patagonian Toothfish (Dissostichus eleginoides). Shallow parts of the plateau (< 20 m) are dominated by beds of Giant Kelp (Macrocystis pyrifera) and encrusting algae (Lithothamnion sp.), with the Bull Kelp (Durvillaea antarctica) occurring along cliff shorelines. These algal communities provide sheltered hunting areas for Killer Whales (Orcinus orca) that visit the islands in spring and summer. The coastline is irregular and mostly comprised of young black lava in many forms, including steep cliff faces, sandy beaches, bays, inlets, and rocky and boulder shores. The beaches and shores provide access to the many seals and penguins that breed at the islands. The terrestrial vegetation occurs either within the unique sub-Antarctic Tundra or Polar Desert biomes that are not found on mainland South Africa. The cold and windy conditions prevent the survival of trees, with the only woody plant species being Acaena magellanica. The Kerguelen Cabbage (Pringlea antiscorbutica), endemic to the South Indian Ocean Province, of which the PEIs form part, is the only megaherb and occurs at the northern extent of its range at the PEIs. Many plants depend on the disturbance of and manuring by seals and seabirds, with some plant species such as A. magellanica and Uncinia compacta using seabirds to disperse their hooked seeds that attach to feathers.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for 3 criteria described in the Global Standard for the Identification of KBAs. Based on current available information, 13 species meet one or more KBA criteria for this site. The KBA trigger species at this site include marine birds and mammals. These species occur as breeding aggregations at the site, and all 13 meet criterion D1 because more than 1% of their global populations occur at the site during the breeding season. Six species are threatened, and also meet the population thresholds for criterion A1. Four bird species regularly present at the site have highly restricted breeding ranges, therefore also meeting criterion B1 for individual geographically restricted species and B2 for assemblages of co-occurring range-restricted species.
Manageability of the site: The site is managed primarily by a South African protected area management authority.
Supersedes another site: Prince Edward Islands Special Nature Reserve ZA101 [100%]
Delineation rationale: The site boundaries follow those of the Prince Edward Island Special Nature Reserve.
Habitats
Summary of habitats in KBA: Rocky areas (33%), Shrubland (32%), Wetland (inland) (22%), Marine coastal/supratidal (13%)
Threats
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Climate change & severe weather | Droughts | Ongoing | |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Unspecified species | Ongoing |
Additional information
Contributors: Gavin Masterson (Fathom Data), Warrick Stewart (Resilience Environmental Advice), Anisha Dayaram (South African National Biodiversity Institute), Maphale Monyeki (South African National Biodiversity Institute), Sediqa Khatieb (South African National Biodiversity Institute), Craig Hilton-Taylor (IUCN)