Ocean currents as a potential dispersal pathway for Antarctica’s most persistent non-native terrestrial insect

Abstract

The non-native midge Eretmoptera murphyi is Antarctica’s most persistent non-native insect and is known to impact the terrestrial ecosystems. It inhabits by considerably increasing litter turnover and availability of soil nutrients. The midge was introduced to Signy Island, South Orkney Islands, from its native South Georgia, and routes of dispersal to date have been aided by human activities, with little known about non-human-assisted methods of dispersal. This study is the first to determine the potential for dispersal of a terrestrial invertebrate species in Antarctica by combining physiological sea water tolerance data with quantitative assessments of ocean current journey times. Fourth instar larvae tolerated sea water submergence for up to 21 days, but submerged egg sacs had significantly reduced hatching success. Using near-surface drifter data, we conclude that ocean current dispersal from Signy Island would not present a risk of species transfer beyond the South Orkney Islands on the tested timescales. However, if E. murphyi were to be introduced to the South Shetlands Islands or Adelaide Island, which are located offshore of the Antarctic Peninsula, there would be a risk of successful oceanic dispersal to neighbouring islands and the Antarctic Peninsula mainland. This study emphasises the need for effective biosecurity measures and demonstrates the role that currently undocumented pathways may have in dispersing non-native species.

Meta‐analysis of Antarctic phylogeography reveals strong sampling bias and critical knowledge gaps

“…Alongside the direct impacts of warming and human activity (Duffy and Lee 2019, Siegert et al 2019), non‐native species could also threaten Antarctic biodiversity and disrupt established biogeographic patterns. Previously uninhabitable areas may soon become available to species with the requisite physiological tolerances to cold and desiccation (Lee et al 2017, Gutt et al 2021), and although oceanic barriers are challenging to cross, they are not impenetrable (Fraser et al 2018, Cárdenas et al 2020, Bartlett et al 2021, Lagostina et al 2021, Maroni et al 2022). Developing an understanding of the physical and evolutionary processes that shape diversity and distributions in Antarctica will be critical for building useful models to forecast and help manage Antarctic ecosystems into the future.…”

Belgica antarctica (Diptera: Chironomidae): A natural model organism for extreme environments

“…High lethality is seen only after a week's exposure to 58.4% NaCl (Baust & Lee, 1987). Similar tolerance to saline and, to a lesser extent, hypersaline conditions is seen in the final-instar larvae of E. murphyi (Bartlett et al, 2021). Exposure to seawater leads to decreased body water content and increased content of the osmolytes glucose and trehalose (Elnitsky et al, 2009).…”

“…Stress resistance is thus one of the most widely studied aspects of the biology of Antarctic arthropods and other invertebrates (Cannon & Block, 1988;Convey, 1996;Peck et al, 2006;Denlinger & Lee, 2010;Convey et al, 2014;Teets & Denlinger, 2014;Everatt et al, 2015). The primary environmental stress challenges facing B. antarctica and its close relative E. murphyi are low temperatures, desiccation, and osmotic stress from exposure to seawater (Baust & Edwards, 1979;Baust & Lee, 1983, 1987Bartlett et al, 2020Bartlett et al, , 2021.…”