Belgica antarctica, a wingless midge, has perfected the art of freezing itself to endure Antarctica's darkest winter months, carving out a unique niche as the continent's only native insect over tens of millions of years.
This hard-earned set of survival skills might be detrimental to its very existence, potentially bringing it to the brink of extinction as climate change nudges polar temperatures ever higher.
Warmer winters in the frozen south have significantly impacted the insect's movements and energy stores, putting the insect in danger of seeing another summer in the future.
The itty-bitty arthropod has the unusual distinction of being the largest animal in the world to never slap a toe in the ocean. Its entire life cycle is spent mostly in moist moss and algae beds, chomping on the greenery and decaying waste.
Even these humble refuges freeze over in Antarctica's harsh winters, locking up precious moisture and threatening to turn the tiny insects into popsicles. So to keep alive, the midge devised a clever strategy to avert death and bide its time.
The midge slowly desiccates itself to protect itself from the effects of ice crystals breaking into its tissues. Generally, individuals have a good likelihood of making it through the summer, even after losing as much as three-quarters of its moisture.
The degree of humidity that gives rise to that good chance is a major factor, as does whether the humidity rehydrates using water vapor from the air or soaks it directly from liquid water. Even minor changes in environmental conditions might make a significant difference in survival rates.
The Antarctic Peninsula, a region nearing the midge's mossy garden, is typically warm between -5 and 0 degrees Celsius. Protected by layers of snow and ice, temperatures may drop in the atmosphere above, with little impact on the midge's mossy garden.
These relatively unprotected conditions may be shifting as temperatures rise as much as half a degree per decade on the peninsula. Increased precipitation may result in more snow, which will reduce the probability of winter freezing.
Researchers collected midge larvae from the surroundings of a station on Anvers Island, at the very edge of the Antarctic Peninsula, to determine how much impact this would have on B. antarctica.
These specimens were then sent back to a lab in the United States where they spent six months living in subtly different winter conditions, ranging from a cold -5 degrees Celsius up to a warm -1 degree. Various kinds of substrate, such as algae, were also examined.
The survivors were examined for signs of movement, tissue damage, and energy stores of carbohydrates, fats, and proteins after defrosting in ice water.
Under normal circumstances, around half of the insects made it through. Warmed by just a few degrees, a mere third survived. Energy stores also varied significantly, with more fat and protein stores being retained in colder environments than in warmer ones.
"These findings coincide with locomotor activity levels, where larvae from the warm winter environment are likely to be the cause of energy drain," the researchers conclude in their research.
"Energy store depletion during late larval instars will likely have irreversible consequences on the energy available for reproduction," says one expert.
If temperatures continue to rise, it's difficult to predict just what effect it will have on long-term growth. It could be a minor inconvenience or a serious blow that wipes out entire populations.
There is a possibility that the midge will have more time to gather larger stores during the summer months.
It is up to the individual to determine whether or not this behavioral check mitigates the adverse effects of a warming environment.
The only insect to call Antarctica home might become yet another victim of our rapidly changing climate.
Functional Ecology is the publication of this research.