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Nature in Balance: The Ecology of South Georgia

Explore the special conditions that make South Georgia a thriving sub-Antarctic ecosystem.

Southern Elephant Seals (Mirounga leonina) alongside King Penguins (Aptenodytes patagonicus) and Gentoo Penguins (Pygoscelis papua) on a beach in South Georgia. Source: George Lemann

This exhibition celebrates the extraordinary biodiversity of South Georgia. These stunning islands are home to a variety of resilient plants and wildlife. South Georgia was once home to sealing and whaling industries that over-exploited natural resources and threatened the island's balance. Today South Georgia is an ecosystem in recovery.

Join us in exploring marine and terrestrial ecosystems and discover why protecting biodiversity is so important for the islands' balance.

Lead image source: Julie Shaughnessy

Around South Georgia, multiple species will colonise the same area. At Cooper Bay you can see Macaroni Penguins (Eudyptes chrysolophus), Chinstrap Penguins (Pygoscelis antarcticus) and Southern Elephant Seals (Mirounga leonina), highlighting the biodiversity of the shores. Source: Andrew Shiva, CC BY-SA 4.0

South Georgia is a hotspot for biodiversity. But what does that mean?

Biological diversity encapsulates the variety of life on Earth. Each small piece of the puzzle is just as important as the others to help maintain resilience and stability. When one piece is removed, it alters the overall picture. This disrupts the natural balance and can occur, for example, when a species becomes extinct, an alien species is introduced or a habitat is damaged or lost.

Biodiversity depends on non-living elements like landscape and geology, water and climate. The variety of geology, soils, topography, geomorphology and hydrology can be described as geodiversity.

The interaction of biodiversity and geodiversity in a particular place plays an important role in forming its ecosystem. Studying biodiversity and geodiversity helps us understand our ecosystems. In South Georgia bedrock, glaciers, climate and the surrounding ocean sets the stage for marine and terrestrial ecosystems to thrive. South Georgia is in a ‘Goldilocks zone’ in the ocean, a place just right for many species to flourish. The perfect placement of the island means that it is rich in wildlife. Most birds and mammals on South Georgia use the ocean as their source for food.

Human activity can disrupt biodiversity, geodiversity and climate, upsetting the balance in the ecosystem. We depend on balanced ecosystems for healthy populations. They supply us with medicine, fresh water, air and food. It is important to monitor and manage our ecosystems to keep the planet alive.

We can piece together the story of South Georgia’s formation looking at its geology. The geology of South Georgia sets it apart from most other South Atlantic islands which are generally volcanic. South Georgia is mostly sedimentary rock (shale and sandstone; pale blue and pale green) with small areas of volcanic rock towards the south-east. Source: British Antarctic Survey, Natural Environment Research Council

The continents were not always arranged as they are today. Continents have split and shifted over hundreds of millions of years to form the world we know today. They are still moving now. Scientists study their movement using satellites, magnetic observation and seismic monitoring. Source: United States Geological Survey (USGS)

Terrestrial ecosystems

South Georgia’s geodiversity sets the stage for its terrestrial ecosystem. The islands’ geology, geography, landscape and climate are the foundations that support life.

South Georgia’s story starts around 180 million years ago, when the supercontinent of Gondwanaland broke up. The breakup pushed the Pacific Ocean plate and the South American plate together to create a volcanic ridge. The southern tip of the ridge became an island off the shore of South America. The oldest parts of South Georgia are from this island.

Sedimentary rock started forming in the sea between the island and South America. This rock makes up the bulk of South Georgia’s bedrock today. Volcanic activity on the ocean floor formed rock formations seen in Larsen Harbour.

Ninety million years ago, South Georgia started moving towards South America. This caused the sedimentary rock to rise out of the sea and fold in formations that are visible around South Georgia today. South Georgia later broke away from South America and for the past 40 million years, it has been moving eastwards on the Scotia Ridge.

South Georgia’s landscape is sculpted by ice and the sea. Erosion during periods of high sea levels created flat headlands. Glaciers scoured out the fjords and bays. Glacial advance and retreat created moraine plains, ridges and terraces. As ice melted, the weight on South Georgia lessened and the land rose further out of the sea. The beaches and lowlands have been ice-free year-round ever since. This is a critical part of how South Georgia’s geodiversity and climate support life.

Rocks

Most of South Georgia’s rock is sedimentary and formed from layers of silt and mud settling over time. There is metamorphic rock in the south-east. Metamorphic rock is formed from other rock at high heat when one continental plate is pushed under another. Few fossils are found in South Georgia’s sandstone and shale. The falling ashes that formed Annenkov Island trapped organisms living on the seafloor making the island rich in fossils.

This striking rock formation is at Busen Point on the approach to Stromness Bay. It was created by the compression and folding of sedimentary rock. The distinctive feature was used by whalers to navigate to the whaling stations in the Bay. Source: Robert Burton

South Georgia viewed from space. Harsh weather systems form over the seas south of South Georgia. The north-east of South Georgia is sheltered from these systems by the Allardyce and Salvesen Ranges that form the spine of the island. This means that the vegetation is better developed on this side of the island. Source: European Space Agency, contains modified Copernicus Sentinel data (2018), processed by ESA

Wandering Albatross (Diomedea exulans) nesting in tussac grassland. Source: Dr Roy Bishop

The ice-free lowland areas have been colonised by plants blowing in from across the sea to form a sub-Antarctic tundra system. Like tundra systems in the Arctic, South Georgia is too cool to support woody plants. Most native species are mosses, lichens and liverworts with only few hardy native ferns and grasses. The coastal flats are dominated by Tussac Grass (Poa flabellata).  Valley floors are often boggy with high peat accumulation covered in mosses, rush and burnet. Rocky outcrops, cliffs, and scree are populated with moss and lichen species that do not need soil to thrive.

South Georgia’s ice-free beaches and grassy lowlands make it the perfect place to nest and breed. South Georgia has no native land mammals, amphibians or reptiles, but its beaches and lowlands are teeming with flying seabirds, penguins and seals in the austral summer. The ocean around South Georgia is both deep and rich in life.

Flying seabirds nest or burrow in tussac, meadows or cliffs while thousands of breeding seals and nesting penguins settle on the beaches. Invertebrates like flies, beetles and spiders live among grasses and mosses. Landbirds nest among the tussac and seek out invertebrates for food. Seals and seabirds hunt for food in the waters surrounding South Georgia while some birds scavenge among penguin colonies and breeding seals.

Plants

South Georgia has over 400 native plant species. They were carried to South Georgia on the wind and by migrating birds from South America and the Falkland Islands. Lichen, mosses, liverwort, and ferns are prominent among the native plants. Plant species in South Georgia have adapted to thriving in extreme conditions. Many have very fine seeds or spores that spread well in the wind and shallow or no roots, allowing them to grow in limited soil conditions. Some can dry out completely and rehydrate to cope with changeable growing conditions. Plants provide food and habitats for invertebrates like beetles, flies and spiders. They also provide shelter for seals and birds.

Southern Elephant Seal (Mirounga leonina) amid tussac at Cooper Bay, South Georgia. Tussac grasslands are often boggy and can grow up to 3 metres tall. Source: Liam Quinn, CC BY-SA 2.0

Invertebrates

There are around 200 species of invertebrates recorded in South Georgia. They include mites, flies, beetles, springtails, worms, and spiders. Invertebrates are an important food source for South Georgia Pipits and Pintails. The invertebrate species in South Georgia have adapted to survive in the cold, harsh environment and several species over-winter. Some species can swim under layers of ice, while others have adapted to develop anti-freeze compounds to lower their bodies’ freezing point. Many are found among vegetation and animal colonies where they find shelter and food.

First day cover commemorating the Survey for Baseline Information of Introduced plants & invertebrates: South Georgia. The stamps have illustrations of six invertebrates identified in South Georgia. The envelope is addressed to Dr & Mrs Roger & Rosy Key, two members of the survey team (address redacted for privacy). Source: Roger Key

South Georgia Pintail (Anas georgica georgica)

Pintails are one of the few landbirds in South Georgia. They are found swimming in both fresh water and the sea near the coast. Here they are swimming in a still body of fresh water. Pintails have diverse diets. They feed on algae and invertebrates but they also scavenge seal carcasses. Their call is a distinctive whistle-like sound.

Source: Oliver Prince

Tumbleweed, SGM.2021.10 Source: South Georgia Museum

Animals and the Ground

Penguins and seals change the ground in South Georgia. They moult in the austral summer, leaving behind feathers and fur in South Georgia. This tumbleweed was formed from penguin feathers. This phenomenon happens as high winds blow moulted feathers together on the outskirts of large penguin colonies.

Seals and penguins use coastal vegetation for shelter and small bodies of water to regulate their temperature while moulting. When they are on land their waste brings nutrients like nitrogen back to the soil. The ground around seal and penguin colonies is healthy but muddy and slippery. Vegetation by seal colonies often gets trampled but when it recovers it grows back stronger because of the nutrients left behind by the animals.

Antarctic Fur Seal male (sitting upright), females (lying around male) and pup (small black seal in front of male). Source: Liam Quinn, CC BY-SA 2.0

Antarctic Fur Seal (Arctocephalus gazella)

Antarctic Fur Seals breed on beaches all over South Georgia. The island is home to around 95% of the global population of Antarctic Fur Seals. The ears of Antarctic Fur Seals are external which sets them apart from Leopard Seals and Southern Elephant Seals. Antarctic Fur Seals have sexual dimorphism, meaning a size difference between males and females. Male adult fur seals reach weights around 120–140 kg and adult females 25–50 kg. Their diet consists of krill and squid. They make use of the coastal vegetation and environment during the breeding and moulting seasons. Antarctic Fur Seals each have a unique scent profile. They use both scent and voice to recognise their pups and  family members.

Antarctic Fur Seals and King Penguins on the beach at Right Whale Bay, South Georgia. The raised beach in the background is home to a colony of around 20,000 breeding King Penguin pairs.

Source: Oliver Prince

Birds

South Georgia is home to rich birdlife. Most of South Georgia’s birds are seabirds feeding on krill, fish and squid. Some birds weather the harsh winters in South Georgia. Others migrate thousands of kilometres over the sea each year. The South Georgia Pipit, South Georgia Pintail, Yellow-billed teals and Snowy Sheathbills are South Georgia’s only landbirds. They feed on land foraging for invertebrates and algae. Pintails and Sheathbills have more diverse diets and can be found scavenging alongside some seabirds among breeding seals and nesting penguins.

Birds in South Georgia are ground nesting. They nest in the shelter from tussac and grasslands or in burrows in the ground or soft scree. Some nest in gaps in the cliffs. South Georgia’s birds were threatened by preying rats and trampling reindeer. Since the rat and reindeer eradications the birds have made a remarkable recovery. Below you can see some of the birds found in South Georgia.

King Penguin (Aptenodytes patagonicus)

Penguins are non-flying seabirds. King Penguins spend nearly 75% of their lives swimming, foraging for fish and squid. They have adapted to a life spent at sea with feet set far back, wing bones fused to flippers and dense, heavy bodies. They are expert divers known to dive up to 240 metres. They breed and nest on beaches in colonies of up to hundreds of thousands of birds. King Penguin calls may sound identical to us, but they can recognise their partner by their call. This helps them find each other in large colonies.  Only a thin shell separates the chick from the sounds of the outside world, so it will already know its parents’ call when it hatches.

Source: Oliver Prince

Wandering Albatross with chick. Source: Ewan Edwards

Wandering Albatross (Diomedea exulans) 

The Wandering Albatross is the world’s largest seabird. They have a wingspan of up to over 3 metres. They migrate tens of thousands of kilometres to nest in sheltered grasslands in South Georgia. While they incubate and rear their chicks, they undergo foraging trips of up to 10,000 kilometres in 10-20 days. Albatross can lock their wings with their shoulder tendon while they are in flight. This allows them to keep their wings straight while conserving energy. Wandering Albatross feed on fish, squid and crustaceans, catching their prey with shallow dives. They have a small gland above their nasal passage which helps them to cope with the high salt levels in their diet by excreting excess salt. Wandering Albatross have long lifespans with some living up to 60 years.

Antarctic Prions. Source: Peter Harrison

The ocean floor around South Georgia is home to a wealth of species including anemones like these. Anemones are part of the same family as jellyfish and coral and have the ability to sting. Source: Blue Green Expeditions

MARINE ECOSYSTEMS

The oceans around South Georgia are some of the most productive in the world. A mix of local conditions that boost growth and ocean currents that bring in food makes the oceans around South Georgia a ‘Goldilocks Zone’ – the perfect hotspot for wildlife. Blooms of phytoplankton (microscopic drifting plants) are the foundation of life here, feeding millions of tiny zooplankton (tiny animals), in turn feeding thousands of other marine animals.

The ocean is made up of different zones, each with its own conditions that support unique forms of life. The benthic zone encompasses the sea floor. It supports organisms such as coral, sponges and echinoderms (for example sea cucumbers or urchins). The pelagic zone refers to the area of open water away from the coast and the sea floor. The surface of the pelagic zone is where we find phytoplankton, which move with the ocean currents and use photosynthesis to make energy. Within these zones are different marine ecosystems encircling the island; the open ocean, coastal ocean and deep-sea ocean.

The springtime phytoplankton communities shown above were spotted between the Falkland Islands to the west and South Georgia Island to the east by the VIIRS instrument aboard the Suomi-NPP satellite on November 16, 2015. Source: NASA Ocean Color Image Gallery

Leopard Seal (Hydrurga leptonyx) in the water. Leopard Seals breed close to Antarctica using the pack ice. Some travel hundreds of miles north to use the open water around South Georgia for hunting, especially in the austral winter. They are solitary creatures – hunting on their own. Source: Blue Green Expeditions

South Georgia sits on the Scotia Ridge which rises from the deep ocean. The edge of the ridge is between 50 to 150 kilometres around South Georgia’s coast. The waters closest to South Georgia get deep quickly reaching a depth of around 500 metres. This deep water goes through a process called upwelling, bringing nutrients to support life at the surface. As wind blows over the surface it ‘pushes’ warmer water out to the open ocean, this is replaced with deeper, colder, nutrient-rich water. The macro-nutrients brought from this zone are crucial including nitrogen, phosphorus and silicate, as well as metallic micronutrients. The animals deep in the sea often seem strange and alien to us. They have adapted to survive in deep waters which have little light, high pressure and cold temperatures.

The open ocean reaches from above the seabed to the ocean surface. This ecosystem supports some of South Georgia’s most famous and charismatic animals, such as seals, whales, penguins and flying seabirds. These animals use the open waters to hunt for prey. Some dive deep in search of food. Southern Elephant Seals can dive to depths of 2000 metres in hunt of prey. Many of these species feed on krill, which form swarms during the austral summer months. It is thought that there are around 500 million tonnes of krill in the Southern Ocean and a Blue Whale can consume 4200 kg of krill in one day.

The deepest waters around South Georgia are in complete darkness. This Comb Jelly (Ctenophora) has adapted to living at these depths. Source: Blue Green Expeditions

Antarctic Krill (Euphausia superba) is a keystone species in the Antarctic marine food web. Source: World Wide Fund for Nature (WWF)

MARINE FOOD WEB

Food webs describe the intricate links between different food chains (flows of energy from one animal to another) in each ecosystem. It is simple in some cases where food chains are short, like the direct path from phytoplankton to krill, and from krill to baleen whales.  Complexity arises when animals eat at different stages along the chain. For example, penguins will eat krill and fish.  Krill and copepods (both zooplankton) will eat each other when resources are less productive. Animals can alter their diets based on availability. Monitoring the diets of the top predators can highlight the changes occurring in the ecosystem. These feeding relationships indicate both the resilience and vulnerability of the marine ecosystem. 

 

Coral and Brittle Star. Corals look plant-like, but they are invertebrates. They feast on tiny zooplankton, using their arms to sweep food into their hidden mouths. The seafloor around South Georgia is rich in them, and they support life around them. Corals protect the seafloor and coastal regions by weakening the intensity of waves. Source: David Barnes

Dragon Fish (Bathydraco joannae) in the sea around South Georgia. This species is rarely collected by scientists. Source: Blue Green Expeditions

Fish provide a key link in the food web. Lanternfish are and important part of the diet of a variety of penguins and seals. Fish also feed humans, making us part of the food web.  Marbled Rock Cod were hunted to near extinction in the 1970s but seem to be recovering. This is assessed by scientific bottom trawls called Groundfish Surveys. The British Antarctic Survey regularly performs Groundfish Surveys on behalf of the South Georgia Government to inform fisheries quotas. The surveys help determine the health of the ecosystem. 

Source: South Georgia Museum

Patagonian Toothfish (Dissostichus eleginoides)

This species is known to grow longer than 2 metres, weigh 100 kilograms and can live for over half a century. Patagonian Toothfish are deep-sea predators. Travelling from the seabed into the water column to hunt their prey; fish, squid and crustaceans. In turn, they are thought to be hunted by Sperm Whale – and possibly even the elusive Giant Squid. Patagonian Toothfish are one of the species humans fish for in South Georgia waters. The fishery is strictly managed by the Government of South Georgia & the South Sandwich Islands (GSGSSI). 

Marine Organisms

Setting up camp on Bird Island in the 1960s. Source: Alec Bottomley

Scientists camping in South Georgia in the 1970s. Source: Geoff Firmin

PROTECTING BIODIVERSITY

South Georgia is an ecosystem in recovery. We have come this far by taking science-based measures to conserve and protect the island. South Georgia is still vulnerable. Environments, the world over, are increasingly under threat from human activity and climate change. Ongoing monitoring and protection are critical to continuing South Georgia’s ecological recovery.  

Scientists from the British Antarctic Survey (BAS) have been monitoring sites on South Georgia such as Bird Island and King Edward Point for decades. This research informs policy and decisions made by the Government of South Georgia & South Sandwich Islands (GSGSSI) who govern this UK Overseas Territory. BAS research helps to shape policies set by international agreements, including the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), International Whaling Commission (IWC) and Agreement for the Conservation of Albatrosses and Petrels (ACAP).  

The biggest conservation achievements are underpinned by science. In 2018, South Georgia was declared rat- and mice-free after a successful invasive species eradication programme, with reindeer removal delivered by GSGSSI and rodents eradicated by the South Georgia Heritage Trust, in partnership with Friends of South Georgia Island (FOSGI) and GSGSSI. The programme eliminated key threats to South Georgia’s ground nesting birds. They have since made a remarkable recovery.   

Learn more about the habitat restoration project
The South Georgia Pipit (Anthus antarcticus)

This sparrow sized bird lives only on South Georgia, but its evocative song was almost lost forever. It had been exterminated from most of South Georgia by rats and was only found nesting on offshore islands.

The success of the habitat restoration has meant that pipit song is heard again around King Edward Point and Grytviken. These small birds can once again be seen feeding on insects in summer and small invertebrates found along the shore in winter. The pipit lays up to four eggs in a nest of dried grass among the tussac and is growing in numbers annually.

Image source: George Lemann

The wreck of coaling ship Bayard in Ocean Harbour, South Georgia. Now overgrown with tussac and a popular nesting spot for Blue-eyed Shags. Source: Thies Matzen

Helicopters were used to eradicate rats and mice from South Georgia by dropping rodent-bait from the air. Three helicopters flew a combined 600 hours over South Georgia during the Habitation Restoration Project. Rodents were introduced accidentally during the whaling industry. Source: South Georgia Heritage Trust

GSGSSI has designated Terrestrial Protected Areas (TPAs) that cover the whole landmass of South Georgia and the South Sandwich Islands. The government regulates and manages work, visits and science in South Georgia to ensure that it is sustainable and with minimal impact to the ecosystem. GSGSSI has also designated the South Georgia and South Sandwich Islands Marine Protected Area (MPA). This MPA is one of the largest in the world, covering an area 5 times the size of the UK. The no-take zone, area where fishing is prohibited, was significantly expanded in 2025 from 12km to 30km around the islands. These designations bring us a step closer to restoring biodiversity and furthering conservation and protection of ecosystems in South Georgia.

Monitoring of specific species informs conservation efforts and governance. Satellite tracking of animals has informed the creation of Important Bird and Biodiversity Areas (IBAs) and Key Biodiversity Areas (KBAs) in the Southern Ocean. This has helped focus conservation efforts where they matter the most.

Long-term monitoring of seabirds, whales, fish and seals help us understand their feeding habits and needs. This helps GSGSSI set quotas for the South Georgia fishery. Albatross and Petrel research identified threats to the species during the breeding and nonbreeding seasons. This led to regulations that greatly reduced seabird mortality (bycatch) in fisheries in South Georgia waters, and internation pressure to do the same elsewhere. Long-term scientific monitoring can also be used to help us understand how climate change affects South Georgia’s ecosystem.

Species protected by SGSSI MPA and ACAP

Top and middle: Endangered, vulnerable, and near threatened species protected by South Georgia and South Sandwich Islands Marine Protected Area (MPA).
Bottom: Three of the seven species breeding at South Georgia that are listed by the Agreement on the Conservation of Albatrosses and Petrels (ACAP)

Map detailing the South Georgia and South Sandwich Islands Marine Protected Area (MPA). Source: Government of South Georgia & the South Sandwich Islands

South Georgia Pintails (Anas georgica georgica) flying over rainbow. Source: Oliver Prince

FURTHER READING

Scientific and conservation work in South Georgia is ongoing. You can follow along and learn more below.

Resources

Acknowledgements

This exhibition would not have been possible without funding from the Natural Environment Research Council (NERC). Plus, the advice and research data from scientists at the British Antarctic Survey.