by Nicholas Sauer
For better or worse, humans have left an impact on every corner of the globe, and Antarctica is no exception. One of the ways humans have altered Antarctica’s unique environment is by unintentionally introducing new plant and animal species to the continent. The presence on the continent of human-introduced novel species can be interpreted as a mark of the Anthropocene, a term scientists use for the recent decades during which human activities have created environmental impacts great enough to constitute distinct geological and earth system change, and a new era in the Earth’s history. While most novel species do not survive Antarctica’s polar elements, a few do. As of 2021, there were eleven known novel invertebrate species, including insects and mollusks, thriving on the more hospitable coastal areas of Antarctica. For context, there are 163 species of bivalves, 568 species of gastropods, and three species of insects that currently make the continent home. Of the three insect species, only the midge B. antarctica, flightless and measuring under a centimeter long, is native to Antarctica. Novel species while not always intrinsically dangerous to their new homes and neighbors, have the potential to change their adopted ecosystems in profound and unforeseen ways.
Eretmoptera murphyi – a novel midge to Antarctica changes nutrient cycling
One of the most fascinating of Antarctica’s human-introduced invertebrate species is the midge Eretmoptera murphyi, that has made Signy Island, Antarctica home since the 1960s. This species of midge inadvertently made its way to the polar South as a stowaway on a scientific expedition focused on plant transplantation. The insects found Signy Island well-suited for colonization: they have no predators there, can survive “ice entrapment,” continue to respire when in water, and produce larvae unfazed by freezing temperatures. The fact that the species is parthenogenetic—that is, reproduces without fertilization—also eases its survival. Each new generation emerges from the soil and melting ice over the course of the summer season and then disperses on the wind, expanding the species’ range. Today the density of some E. murphyi populations on Signy exceed that of any other insect population on the island.
Furthermore, the midge discovered an excellent food source in the island’s abundant peat deposits. E. murphyi consumes the peat and then excretes it as nitrogen-rich soil. In the area that the midge occupies, the amount of nitrogen in the soil matches what a scientist could expect to find in soil surrounding a seal colony. The novel midge’s excretion of nitrogen is “opening nutrient cycling bottlenecks” on the island says Jesamine Bartlett, a scientist studying E. murphyi on Signy. Bartlett compares the species to an earthworm regarding its creation of nutrient-rich soil. However, per Bartlett, the island has never before hosted a creature that performed such a role to her knowledge. It remains to be seen just how this heightened level of nitrogen in the soil—which acts as a fertilizer—could alter the abundance of the island’s plant populations, particularly that of mosses, hair grass, and pearlwort. In addition to its potential effect on Signy’s flora, scientists caution that E. murphyi could eventually outcompete and displace the island’s pre-existing insect populations, particularly that of B. antarctica, Antarctica’s only endemic insect species and one that can only reproduce via fertilization. Because it is parthenogenetic and reproduces more easily, scientists are curious to see if the novel midge E. murphyi could one day prove heartier than the native species, and what the presence of the novel midge means for Signy Island’s biodiversity in the long-term.
How Are Novel Species Introduced to Antarctica?
Species such as E. murphyi spread into new territories traveling with humans, often via the laces and tread of shoes, acting as literal living components of our footprint. Seeds of non-native plants hitch a ride to new habitats on human travelers’ clothes. In fact, each tourist unknowingly brings on average an estimated nine seeds with them to Antarctica according to Stephen Chown of Stellenbosch University in South Africa. In 2010 there were approximately 40,000 tourists who visited the continent. That’s potentially 360,000 novel seeds introduced to Antarctica in just one year, though most will not successfully establish themselves. According to a study led by researchers from Monash University in Australia, only sixteen percent of Important Bird Areas in Antarctica are found in regions “negligibly impacted” by humans. These scholars and conservationists argue that the image of Antarctica as “remote” is unhelpful and obscures the profound impact humans have on its coastal regions, regions that contain the continent’s greatest biodiversity. The goal of the team’s research is to encourage Antarctic Treaty nations to take concrete steps to further protect Antarctica’s natural environment and wildlife. As a landmass not under the jurisdiction of any one nation, Antarctica’s ecological protection hinges on global cooperation.
More than ever before, maintaining Antarctica’s unique ecosystems—safeguarding the continent’s biosecurity—is of paramount importance. The scientific community and the ecotourism industry are making efforts to adhere stringently to the Antarctic Treaty, the Antarctic Conservation Act, and Antarctic Science and Tourism Conservation Act, international agreements in place to protect the continent’s delicate ecology and facilitate ethical research and tourism. Per these agreements, travelers to Antarctica are prohibited from bringing seeds, plants, or animals including insects onto the continent. Travelers are also barred from bringing probiotics and SCOBY (symbiotic culture of bacteria and yeast), a key ingredient of kombucha and yogurt. Both products contain “biologically viable organisms”—bacteria—that could have an adverse effect on the Antarctic environment if left uncontrolled. Under the Antarctic treaties, cargo en route to Antarctica must be thoroughly inspected and sanitized before being shipped and unloaded. Customs inspectors from treaty-member nations are on the lookout for rotting fruits and vegetables, food scraps, spores, mold, soil, living animals, and signs of living animals like wasps’ nests, and a vast array of other “biosecurity risk material.” The United States’ Antarctic Program Participant Guide asks that prospective researchers make sure that “there are no seeds or other plant parts caught in Velcro, no mud on boots, and no grass inside cuffs.” Even the smallest of novel organic materials onboard ship or onboard a traveler’s sleeve have the potential to impact Antarctica’s isolated environment.
Antarctica in the Anthropocene
In the profoundly interconnected world of the Anthropocene, people have introduced many novel species to Antarctica, be they mollusks attached to a ship’s hull, seeds stuck to a scientist’s parka, or midges clinging to a hiking boot or plant specimen. Novel species cause direct changes to the local ecology, and the impacts may be getting more dire, as the continent is also being altered by human-caused global climate change. Already Antarctica is warming five times as fast as the global average, and its ice sheets are melting (with grim consequences to the coastal regions everywhere as sea levels rise). Global climate change can only be solved through people and nations working collaboratively to reduce dependence on fossil fuels. And in the meantime in Antarctica, as we travel deeper into the twenty-first century, the scientific community and governments around the world are learning to be more mindful of the human impact on Earth’s southernmost continent and searching for ways—such as better biosecurity—to keep Antarctica’s unique ecology as intact and resilient as possible.
Nicholas Sauer is a Gallery Experience Presenter in CMNH’s Life Long Learning Department. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.
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Carnegie Museum of Natural History Blog Citation InformationBlog author: Sauer, Nicholas
Publication date: March 2, 2022