Non-native midge species alters antarctic soil ecosystem, unlocking nutrient cycle

The British Antarctic Survey (BAS) and the University of Birmingham have conducted research revealing the significant impact of a non-native midge species on Signy Island in Antarctica. This flightless midge, Eretmoptera murphyi, has been found to enhance plant decomposition, leading to a three to five-fold increase in soil nitrate levels compared to areas without the midge. The study, published in the journal Soil Biology and Biochemistry, was part of Dr. Jesamine Bartlett’s Ph.D. project and highlights the midge’s role as an “ecosystem engineer” by unlocking nutrients in the soil, similar to earthworms in temperate soil systems.

Eretmoptera murphyi is originally from South Georgia in the sub-Antarctic region and was unintentionally introduced to Signy Island during a botany experiment in the 1960s. Its population expansion became apparent in the 1980s. Previously, the only areas on Signy Island with high nutrient levels were associated with marine species, such as penguin colonies and seal wallows. However, the midge’s presence has led to soil nitrate levels comparable to those near seal wallows due to the larvae’s high population densities, which can exceed 20,000 individuals per square meter at certain sites.

Human activities, primarily researchers and tourists unknowingly transporting the midges on their footwear, have facilitated the species’ spread on the island. The midge’s ability to survive in seawater suggests the possibility of colonization on other islands in the future.

Professor Peter Convey, a terrestrial ecologist at BAS, emphasizes the importance of protecting the Antarctic ecosystem, which has had limited encounters with invasive species thus far. This research sheds light on how even tiny animals can significantly impact the environment. The harsh Antarctic conditions, including low temperatures, moisture, and nutrient availability, act as barriers against invasions. However, as temperatures rise and the midges release nutrients, the door may open for other invasive species.

Dr. Scott Hayward, an ecologist at the University of Birmingham, stresses the need to monitor the midge’s spread and its impacts on Signy Island. This understanding is crucial for comprehending the potential effects on other Antarctic ecosystems, as the midge has the capacity to survive in various locations across the region and its activities, combined with climate change, may accelerate the process further.

Source: British Antarctic Survey

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