Life cycle and phenology of an Antarctic invader: the flightless chironomid midge, Eretmoptera murphyi

Jesamine C Bartlett,Scott A L Hayward,Peter Convey

doi:10.1007/s00300-018-2403-5

Jesamine C Bartlett, Scott A L Hayward + Show 1 more

Open Access

https://doi.org/10.1007/s00300-018-2403-5

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Journal: Polar Biology	Publication Date: Sep 29, 2018
Citations: 15	License type: open-access

Affiliation: University of Birmingham, British Antarctic Survey

Abstract

Knowledge of the life cycles of non-native species in Antarctica is key to understanding their ability to establish and spread to new regions. Through laboratory studies and field observations on Signy Island (South Orkney Islands, maritime Antarctic), we detail the life stages and phenology of Eretmoptera murphyi (Schaeffer 1914), a brachypterous chironomid midge introduced to Signy in the 1960s from sub-Antarctic South Georgia where it is endemic. We confirm that the species is parthenogenetic and suggest that this enables E. murphyi to have an adult emergence period that extends across the entire maritime Antarctic summer season, unlike its sexually reproducing sister species Belgica antarctica which is itself endemic to the Antarctic Peninsula and South Shetland Islands. We report details of previously undescribed life stages, including verification of four larval instars, pupal development, egg gestation and development, reproductive viability and discuss potential environmental cues for transitioning between these developmental stages. Whilst reproductive success is limited to an extent by high mortality at eclosion, failure to oviposit and low egg-hatching rate, the population is still able to potentially double in size with every life cycle.

Highlights

The sub-Antarctic islands, with a longer history and greater level of human influence than any other part of the Antarctic (Convey 2013), have a greater number of non-native species than the more extreme maritime and continental Antarctic regions further south (Convey and Lebouvier 2009; Frenot et al 2005)
Salinity was largely stable, with only one spike during a week of high storm activity detected in the vegetation layer, when it rose to 425 μS from an average of 174 ± 45 μS SE, n = 7
This study provides the first comprehensive documentation of the life cycle of E. murphyi, a flightless chironomid midge that is currently expanding its distribution following anthropogenic introduction to Signy Island

Summary

Introduction

The sub-Antarctic islands, with a longer history and greater level of human influence than any other part of the Antarctic (Convey 2013), have a greater number of non-native species than the more extreme maritime and continental Antarctic regions further south (Convey and Lebouvier 2009; Frenot et al 2005). With synergy between high and increasing levels of human activity in this region of the Antarctic, and recent rapid rates of regional climate change, further establishment of nonnative species is predicted, presenting fundamental challenges to the protection and conservation of Antarctic terrestrial biodiversity, and to the management and governance processes in the Antarctic (Chown et al 2012; Chown and Convey 2016; Hughes and Worland 2010; Tin et al 2009). Its larvae have the capacity to rapidly cold harden, cryoprotectively dehydrate (Everatt et al 2012, 2015; Worland 2010), respire in water and withstand ice entrapment (Everatt et al 2014) These traits have allowed it to succeed in the maritime Antarctic, which is more extreme in comparison with the species’ native sub-Antarctic South Georgia. The sub-Antarctic has a relatively stable and chronically cool oceanicinfluenced climate year-round

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