Marielandia Antarctic tundra

• Category: Grassland, Tundra, and Human Biomes.
• Geographic Location: Antarctica.
• Summary: One of the simplest and harshest terrestrial ecosystems on Earth is experiencing rapid environmental change.

At a distance, a visitor to Antarctica’s rocky coast may see nothing but penguins against a lifeless-looking icy backdrop. Closer to shore, however, one of the world’s simplest terrestrial ecosystems comes into view: tundra populated by low-lying plants, invertebrates, and microbes. This tundra ecosystem is at its most diverse and abundant in Marielandia, a region known most commonly as the Antarctic Peninsula and its nearby islands. Although the Marielandia Antarctic tundra has a short history of direct human contact, the biome is changing rapidly because of human activities.

The Antarctic Peninsula is a curvy, roughly triangular piece of land jutting 777 miles (1,250 kilometers) from the western part of the continent toward South America. The moderating influence of the Southern Ocean helps keep the peninsula warmer than the rest of Antarctica. From December to February, its average summer air temperatures are just above 32 degrees F (0 degrees C), whereas its average winter air temperatures from June through August range from 21 degrees F (-6 degrees C) on the west coast to -9 degrees F (-23 degrees C) on the east coast. The peninsula is also wetter than Antarctica’s dry interior. Palmer Station, on Anvers Island, gets an average of 27 inches (682 millimeters) of liquid precipitation in the form of rain and melted snow each year.

Biodiversity

The Marielandia Antarctic tundra has more than 300 species of lichens, more than 100 species of mosses and liverworts, one type of terrestrial alga, and two species of flowering plants. There are even fewer types of fauna with just under 100 species of free-living mites, springtails, nematode worms, rotifers, tardigrades, and flies. For comparison, at similar northern latitudes in Iceland, there are 329 species of flowering plants, and about 800 species of nonmarine invertebrates on the Svalbard Archipelago in Norway.

Terrestrial life in Marielandia tends to be restricted to ice-free coastal fringes where temperatures are the highest and liquid water is more freely available. Even so, the harsh environment poses multiple challenges. The short growing season is marked by low temperatures and rapid transitions between freezing and thawing. In the summer, twenty-one to twenty-four hours of daylight daily exposes organisms to high levels of radiation. Although the air is cold, ground temperatures can spike to more than 75 degrees F (25 degrees C), increasing the risk of dehydration in an already dry environment.

Marine animals such as penguins and seals deposit nutrient-rich guano, which fertilizes plants and feeds invertebrates and microbial populations. But these animals also trample vegetation, creating large bare patches where moss and grass once grew in abundance. Organisms here must also deal with winds that fling salt spray and abrasive grit to shore.

Marielandia’s tundra inhabitants have multiple adaptations that help them thrive despite harsh conditions. Lichens tend to be brilliantly colored because of natural sunscreens that protect their cells from ultraviolet (UV) radiation. Some moss species can temporarily shut down cellular activity when water is in short supply. Springtails, mites, and the Antarctic cushion plant (Colobanthus quitensis) avoid chilling damage by supercooling, meaning that their tissues remain unfrozen even when cooled well below 32 degrees F (0 degrees C). Antarctic hair grass (Deschampsia antarctica) and the wingless Antarctic midge (Belgica antarctica), on the other hand, can survive internal ice formation. Both freeze-tolerant species accumulate special proteins and large quantities of carbohydrates that reduce the size and number of potentially damaging ice crystals that form within their bodies.

One of the best protections against extreme cold is snow and ice. In the winter, a blanket of snow can provide an insulating microhabitat for both invertebrates and plants. Even if the air above the snow is -40 degrees F (-40 degrees C), the temperature beneath the frozen blanket remains a cozy 23 degrees F (-5 degrees Celsius) or warmer.

Conservation Efforts

Since 1961, Antarctica has been governed by an international treaty that sets aside the continent for scientific purposes. No one lives in Antarctica permanently, but each year about 4,000 scientists and support personnel and 30,000 tourists visit the region. More than 90 percent of tourism activities occur in western Marielandia. The Antarctic Treaty heavily regulates the activities of researchers and tourists alike. Hazardous waste, for example, must be removed from the continent, and visitors must keep their distance from wildlife.

Another international treaty is helping stabilize the ozone hole, a region of low ozone concentration that forms over Antarctica each spring. Earth’s ozone layer, which absorbs harmful UV in sunlight, has been damaged by chemicals formerly used in refrigerators, aerosol cans, and other industrial and household items. Many ozone-depleting chemicals are being phased out under the Montreal Protocol, finalized in 1987, but Antarctic ozone concentrations are not expected to recover until late in the twenty-first century. By 2019, the use of ozone depleting chemicals was outlawed by 197 countries around the world and scientists concurred that the ozone layer is slowly recovering as a result.

Environmental Threats

One of the most pressing threats to the Marielandia Antarctic tundra is climate change. The western Antarctic Peninsula is one of the fastest-warming regions on Earth, with winter temperatures increasing five times faster than the global average. The warming here has been accompanied by decreases in cloud cover, increased precipitation in some areas, and changes in storm patterns. The potential effects of these changes are still not well understood.

In the short term, warmer and wetter conditions likely will encourage plant growth and open new habitats by melting glacial ice. However, reduced snow and cloud cover may make freeze-thaw cycles more frequent, which early research suggests can damage both plants and invertebrates. And despite the restrictions of the Antarctic treaty, non-native species are more likely to invade Marielandia as conditions become milder. An international research team investigating invasive species in the Antartic Peninsula identified approximately thirteen invasie species and assessed their likelihood to threaten the biodiversity of the peninsula. They were assessed using three criteria, "their risk of coming to the Antarctic Peninsula, the risk of surviving and reproducing and the risk of causing a negative impact on the biodiversity and ecosystems of the region." The researchers determined the species of most concern included the Chilean mussel, the Mediterranean mussel, edible seaweed known as wakame, and some species of crabs, mites, and some insects. They also identified land plants such as Leptinella scariosa and Leptinella plumose. Invasive species can arrive to a new location a variety of ways, include by foot traffic, attached to or aboard a boat, or mixed in with supplies being delivered to the peninsula. Once invasive species take root and adapt to the new area, it can be very difficult and costly to remove them, especially before they do damage to the existing ecosystem. Invasive species are kown to disrupt the new area's delicate ecosystem, potentially outcompeting native species for food and resources, altering food webs, and even leading to local extinctions. On example scientists found in the mid 2010s, and which has only grown through the 2020s, was an overabundance of king crabs migrating to the Antarctic Peninsula near the continental shelf. If they grow their range as the wate temperature continues to gradually warm, they will threaten the delicate ecosystem of sea stars and sea urchins that live along the shelf.

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