Small insect as a herald of Antarctic climate change | Polarjournal
The small midge Parochlus steinenii, which is not one of the stinging species, is only a few millimeters in size. Until now, the animals have only been found on sub-Antarctic islands, but could also thrive in Antarctica due to global warming. Photo: Nanopore

Insects virtually have populated the entire globe, including the Polar regions. But while the numbers of species and individuals in the north are very high, in Antarctica the situation is the other way around. Thanks to the remote location of the sub-Antarctic islands and the continent, only two native species are known and only one of them is also winged: Parochlus steinenii. But this animal, which is only a few millimeters in size, could serve as a herald of climate-related changes in Antarctica, according to a new study.

The paper, published this week in the journal Scientific Reports, concludes that the small midge has the potential to display climatic changes on the Antarctic continent. “If the predictions generated by recent climate models are correct, freshwater ecosystems on the Antarctic Peninsula may be harshly affected, thus affecting the persistence of P. steinenii in its current distribution,” the authors write in their paper. The team led by Dr. Tamara Contador and Melisa Gañan from the Universidad de Magallanes, Chile, the lead authors of the study, could be an “effective guardian of climate change in antarctic terrestrial and aquatic ecosystems”, as the habitat will change greatly due to global warming on the islands and the Antarctic Peninsula. The peninsula is one of the fastest warming regions on earth.

The midge species requires freshwater ponds in which the eggs can be laid. The larvae then hatch, feed on algae and pupate. The adult animals then hatch in the spring to mate. However, they do not survive the following winter. Photo: Gonzalo Arriagada

The life history of Parochlus steinenii includes a phase in which the animals depend on freshwater ponds. Since these freeze in winter, the larvae of the insects survive this time. In spring, the adults hatch to mate. The research team found that the animals in the South Shetlands are most common on Deception, Livingston and King George Island. There, the conditions for the specific life history are most suitable. Scientists then used the latest climate models to identify regions along the Antarctic Peninsula that could provide suitable habitats in a warming world. It turned out that by the end of the century, the animals could find various new habitats further south and along the coast of the Peninsula. At the same time, however, conditions in their current location would deteriorate, the researchers conclude. Overall, however, the dispersal depends on how the climate change in Antarctica will develop. Because the mosquitoes are temperature sensitive in their various development stages and a stronger warming would also bring a greater dispersal.

The South Shetland Islands are located west of the Antarctic Peninsula and are of volcanic origin. Researchers found the largest midge numbers on the well-known islands of Deception, Livingston and King George Island.

But the question arises as to how the midges would make the leap across the Bransfield Strait, which lies between the archipelago and the Antarctic Peninsula. Because the animals, which are only a few millimeters in size, cannot cross the 100-kilometer-wide waterway on their own, even with wind support, says Tamara Contador and her team. It is more likely that humans will unknowingly support the dispersal. “Human activity (movement by cargo, ship, aircraft and overland travel) in Antarctica has a substantial potential for transporting species from one biogeographic region to another,” the authors write. Since the potentially new areas are in the areas of increased human activity (tourism and science), it is also likely that P. steinenii will be able to reach these areas in this way. If the animals survive there, this is an effective sign that this region’s climate has changed accordingly, i.e. has warmed up, the research team concludes.

The study’s lead author, Dr. Tamara Contador, has been studying the effects of global warming on the Antarctic Peninsula on freshwater and land systems for some time. Photo: Universidad de Magallanes

Source: Contador et al. (2020) Sci Rep 10:9087 (2020)

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