Antarctic Studies Show Lichens to be Excellent Biomonitors of Climate Change

Abstract

Lichens have been used as biomonitors for multiple purposes. They are well-known as air pollution indicators around urban and industrial centers. More recently, several attempts have been made to use lichens as monitors of climate change especially in alpine and polar regions. In this paper, we review the value of saxicolous lichens for monitoring environmental changes in Antarctic regions. The pristine Antarctica offers a unique opportunity to study the effects of climate change along a latitudinal gradient that extends between 62° and 87° S. Both lichen species diversity and thallus growth rate seem to show significant correlations to mean annual temperature for gradients across the continent as well as to short time climate oscillation in the Antarctic Peninsula. Competition interactions appear to be small so that individual thalli develop in balance with environmental conditions and, as a result, can indicate the trends in productivity for discrete time intervals over long periods of time.

Study of Ecophysiological Responses of the Antarctic Fruticose Lichen Cladonia borealis Using the PAM Fluorescence System under Natural and Laboratory Conditions

“…Photosynthetic performance of lichens generally increases 1-2 h after sunrise, and then rapidly decreases because high irradiation and an increase in temperature cause CO 2 exchange to cease under the desiccating conditions [42]. Indeed, the growth rate of Usnea antarctica was sensitive to decreasing mean temperatures [23,24], and approximately 1000 µmol/m 2 /s light intensity was insufficient to induce photoinhibition [26,27]. Such photosynthetic features of Usnea sp.…”

“…In recent decades, lichens have been widely used in environmental monitoring, especially to study the effect of air pollution; however, their role as a bio-indicator reflecting climate changes in the Antarctic region was recently reassessed [23,24]. Approximately 400 species of lichens reside on dry and rocky surfaces rather than in wet habitats in the Antarctic Peninsula [24].…”

“…In recent decades, lichens have been widely used in environmental monitoring, especially to study the effect of air pollution; however, their role as a bio-indicator reflecting climate changes in the Antarctic region was recently reassessed [23,24]. Approximately 400 species of lichens reside on dry and rocky surfaces rather than in wet habitats in the Antarctic Peninsula [24]. Members of the lichen genus Usnea are distributed across most dry habitats of Antarctica and have been used to investigate ecophysiology, antioxidant production, and photoinhibition responses and in long-term and short-term monitoring studies [23][24][25][26][27][28].…”

“…Members of the lichen genus Usnea are distributed across most dry habitats of Antarctica and have been used to investigate ecophysiology, antioxidant production, and photoinhibition responses and in long-term and short-term monitoring studies [23][24][25][26][27][28]. In U. antarctica, for example, their growth rate is strongly correlated with mean summer temperature changes, and photoinhibitory quenching (qI)-a component of NPQ-mainly works to protect photosystems from high light intensity [23,24,26,27]. In addition, a low NPQ response is consistent with the finding that a small amount of glutathione is induced by high light levels, indicating that U. antarctica is likely to produce secondary compounds to protect against excess light [28].…”

Myco- and photobiont associations in crustose lichens in the McMurdo Dry Valleys (Antarctica) reveal high differentiation along an elevational gradient

“…Thus, it appears that symbiotic interactions in lichens can react very sensitively to environmental change although this conclusion is based on a small database, and these responses have been investigated only in a few species (Allen and Lendemer 2016;Colesie et al 2014b;Sancho et al 2017). In general, there is agreement that climatic changes will influence the diversity, abundance and growth of lichens (Sancho et al 2017) and that lichens therefore represent excellent bioindicators for processes associated with global warming (Alatalo et al 2015;Allen and Lendemer 2016;Bassler et al 2016;Sancho et al 2019).…”