The terrestrial midge, Belgica antarctica, occupies a diverse range of microhabitats along the Antarctic Peninsula. Although overwintering larvae have the physiological potential to survive by freezing or cryoprotective dehydration, use of the latter strategy may be constrained by inoculative freezing within hibernacula. To investigate the influence of microhabitat type on larval overwintering, we selected four substrate types that differed markedly in their composition and hydric characteristics. Organic content of these substrates ranged from 14 to 89 %. High organic content was associated with higher values for saturation moisture content (up to 2.0 H2O g-1 dry mass) as well as elevated levels of field moisture content. Seasonal values of field moisture content remained near or above the saturation moisture value for each microhabitat type, and when larvae were cooled in substrates rehydrated to field-based levels, they were unable to avoid inoculation by environmental ice, regardless of substrate type. Consequently, our data suggest that wet hibernacula would force most larvae to overwinter in a frozen state. Yet, dehydrated larvae were collected in April during the seasonal transition to winter suggesting that spatial and temporal variations in precipitation and microhabitat conditions may expose larvae to dehydration and promote larval overwintering in a cryoprotectively dehydrated state.
|Number of pages||9|
|State||Published - Jun 2014|
Bibliographical noteFunding Information:
Acknowledgments This research was supported by the National Science Foundation (ANT-0837559 and ANT-0837613). We are grateful for the hard work and assistance of the support staff at Palmer Station. We also appreciate data provided by the University of Wisconsin-Madison Antarctic Meteorological Research Center (NSF Grant Number: ANT-1141908). John Bailer, Jon Costanzo, Kathleen Killian, Paul Schaeffer, and three anonymous reviewers provided critical comments and suggestions on this manuscript.
- Antarctic Peninsula
- Cryoprotective dehydration
- Freeze tolerance
- Inoculative freezing
ASJC Scopus subject areas
- Agricultural and Biological Sciences (all)