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examBoard: Cambridge
examType: IGCSE
lessonTitle: Antarctic Abiotic and Biotic Factors
Antarctica is the coldest, windiest and driest continent on Earth. Despite these extreme conditions, it supports a unique ecosystem adapted to survive in one of the planet's harshest environments. Understanding the abiotic (non-living) and biotic (living) factors of Antarctica helps us appreciate how ecosystems function in extreme conditions and why they're particularly vulnerable to change.
Key Definitions:
Antarctica's extreme abiotic conditions create one of the most challenging environments for life on Earth. These factors significantly influence which organisms can survive there and how they adapt.
Antarctica holds the record for the coldest temperature ever recorded on Earth: -89.2°C at Vostok Station. Average winter temperatures range from -40°C to -70°C, while summer temperatures along the coast may reach just above freezing. These extreme temperatures require special adaptations for survival.
Katabatic winds can reach speeds of over 200 km/h, blowing from the high interior plateau toward the coast. These winds increase the wind chill factor, making the effective temperature even lower. They also create snow-free areas called "dry valleys" where almost nothing can grow.
Antarctica experiences extreme seasonal variations in daylight. During summer, the sun doesn't set for months (24-hour daylight), while winter brings months of complete darkness. This creates unique challenges for photosynthetic organisms and affects animal behaviour patterns.
Despite being covered in ice, Antarctica is technically a desert, receiving only about 200mm of precipitation annually (mostly as snow). The interior receives even less - as little as 50mm per year. This limited moisture creates additional challenges for life.
About 98% of Antarctica is covered by ice, with an average thickness of 1.6km. This ice sheet contains about 90% of the world's fresh water. The ice limits soil development and creates physical barriers for organisms, but also provides habitat for some species.
The Southern Ocean surrounding Antarctica is rich in nutrients due to upwelling currents. It moderates coastal temperatures and provides essential resources for marine life. The seasonal formation and melting of sea ice creates important habitats and influences global ocean circulation.
Despite the harsh conditions, Antarctica supports a surprising diversity of life, particularly in coastal areas and the surrounding ocean. Most organisms display remarkable adaptations to survive the extreme environment.
Land-based life in Antarctica is limited and primarily consists of simple organisms. No native land mammals, reptiles, or amphibians exist in Antarctica.
Only two flowering plant species exist in Antarctica: Antarctic hair grass and Antarctic pearlwort, found mainly on the Antarctic Peninsula. Mosses and lichens are more common, growing in ice-free areas during summer months. These plants are typically small and grow close to the ground to avoid wind damage.
Tiny invertebrates like springtails, mites and tardigrades dominate terrestrial ecosystems. The largest purely terrestrial animal is the Antarctic midge (Belgica antarctica), only 6mm long. These invertebrates often have antifreeze compounds in their bodies and can enter dormant states during winter.
Bacteria, fungi and algae form the foundation of terrestrial food webs. Some live in extreme microhabitats like dry valleys or even within rocks (endolithic). Many can survive being frozen and have enzymes that function at very low temperatures.
The richest biodiversity in Antarctica is found in marine environments, where the Southern Ocean provides nutrients and relatively stable conditions compared to land.
Several penguin species (Emperor, Adélie, Chinstrap, Gentoo) breed in Antarctica. Other seabirds include skuas, petrels and albatrosses. These birds have dense feathers, thick fat layers and behavioural adaptations like huddling (penguins) to conserve heat. Most migrate north during winter.
Seals (Weddell, crabeater, leopard, Ross, southern elephant and fur seals) and whales (blue, humpback, minke, orca) feed in Antarctic waters. They have thick blubber layers for insulation and typically migrate seasonally. No land mammals are native to Antarctica.
Krill (Euphausia superba) form the cornerstone of the Antarctic food web, supporting most larger animals. Other invertebrates include squid, octopus, sea spiders and various crustaceans. Many have evolved antifreeze proteins to prevent ice crystals forming in their bodies.
Organisms living in Antarctica have evolved remarkable adaptations to survive the extreme abiotic conditions. These adaptations demonstrate how biotic factors respond to abiotic challenges.
Emperor penguins (Aptenodytes forsteri) demonstrate extraordinary adaptations to Antarctica's extreme conditions. They breed during the Antarctic winter when temperatures drop below -40°C and winds reach 200 km/h. Males incubate a single egg on their feet for about 65 days while females return to the sea to feed. During this time, males don't eat and lose up to 45% of their body weight.
To survive, they have:
This remarkable breeding strategy allows chicks to hatch in spring when conditions improve and food becomes more available, but it makes Emperor penguins particularly vulnerable to climate change impacts on sea ice.
The relationship between living organisms and their physical environment in Antarctica demonstrates key ecological principles:
In Antarctica, abiotic factors like extreme cold and limited water availability act as limiting factors that determine which species can survive. For example, only two flowering plant species can survive on the Antarctic continent due to these constraints. The principle of limiting factors explains why biodiversity increases as you move from the interior to coastal regions where conditions are less extreme.
Nutrient cycling in Antarctica is slow due to low temperatures limiting decomposition. However, coastal areas with penguin and seal colonies create "hotspots" of nutrients. Penguin guano (droppings) provides nitrogen and phosphorus that supports small plant communities. These nutrient-enriched areas demonstrate how biotic factors can modify abiotic conditions.
Antarctica's ecosystems are particularly vulnerable to environmental changes due to their extreme specialisation and the harsh conditions they've adapted to.
The Antarctic Peninsula is one of the fastest-warming regions on Earth, with temperatures rising by about 3°C since 1950. This warming is causing changes in sea ice formation, affecting species like Adélie penguins that depend on sea ice for breeding and feeding. Reduced sea ice also impacts krill populations, the foundation of the Antarctic food web.
Despite its remoteness, Antarctica faces impacts from human activities including research stations, tourism and historical exploitation (whaling and sealing). Pollution, introduced species and habitat disturbance pose threats to native ecosystems. The Antarctic Treaty System provides some protection, but challenges remain as human presence increases.
Antarctic krill (Euphausia superba) are small crustaceans that form the basis of the Antarctic food web, supporting penguins, seals, whales and many fish species. Krill depend on sea ice for their life cycle - they feed on algae that grows on the underside of ice and use ice for protection from predators.
Research indicates that krill populations have declined by up to 80% in some areas since the 1970s, primarily due to reduced sea ice coverage caused by climate change. This decline has serious implications for the entire ecosystem, as many predators have specialised diets heavily dependent on krill.
The case of krill demonstrates how changes to abiotic factors (temperature and ice coverage) can have cascading effects through biotic components of an ecosystem, potentially disrupting food webs and threatening species that have evolved in isolation for millions of years.
Antarctica's ecosystems represent some of the most extreme environments on Earth where life has adapted. The interplay between harsh abiotic factors and specialised biotic components creates a fragile balance that is increasingly threatened by global environmental change. Understanding these relationships helps us appreciate both the resilience and vulnerability of Earth's ecosystems.
The study of Antarctic ecosystems provides valuable insights into adaptation, ecosystem functioning under extreme conditions and early warning signs of global environmental change. As one of Earth's last relatively pristine environments, Antarctica serves as both a natural laboratory and a reminder of our responsibility to protect unique ecosystems.
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