Moss in a Changing World
August 8, 2019
By Casey Nicholls, Volunteer Writer
Scientific research and media narratives tend to focus on how species are struggling to cope with climatic shifts rather than the ways that certain species are demonstrating resilience in response to ecological change. In glacial ecosystems, the retreating and shrinking glaciers and thawing permafrost poses significant risks to the futures of various species. However, Catherine Lafarge et al. (2013) made a discovery that speaks to the biological resilience of certain forms of life in polar landscapes.
While conducting research around the receding Teardrop Glacier on Ellesmere Island in Nunavut, La Farge et al. (2013) came across a moss that exhibited signs of life despite having been, until recently, imprisoned under a 100-foot thick glacier for hundreds of years. The Aulacomnium turgidum was blackened but also displayed a green color, which prompted the team to collect samples of that species and other recently exposed bryophyte species along the margin of the Teardrop Glacier.
The samples were returned to the Edmonton lab to undergo radiocarbon dating and for in vitro cultures to test their potential for regrowth after having been confined in ice. The radiocarbon dates on three of the subglacial samples ranged from 404.5 to 614.5 calibrated years Before Present. Out of the 24 samples collected for the culture experiments, 11 indicated regrowth from seven subglacial specimens of four different species. A. turgidum exhibited the most consistent regeneration and produced seven in vitro cultures from three subglacial specimens. Additionally, Distichium capillaceum, Encalypta procera, and Syntrichia ruralis regenerated from parental subglacial samples.
The key to bryophyte resiliency in polar environments lies in their ability to desiccate in unfavorable environmental conditions and their capacity for cellular dedifferentiation. When temperatures drop below freezing, moss and other bryophytes dehydrate themselves to prevent cellular damage caused by ice forming in their tissues. Furthermore, bryophytes are clonal organisms that are made up of totipotent cells. Like stem cells in human embryos, totipotent cells are capable of dedifferentiating into a meristematic state which can then be reprogrammed as the different types of tissues that make up the bryophyte. The observations and experiments of La Farge et al. (2013) plainly speaks to the evolutionary course of bryophytes which has led them to exhibit incredible biological resilience in polar environments.
As polar environments continue to undergo significant climatic shifts, it is imperative that research is conducted to understand how these changes will affect the human communities in Northern areas as well as the ecosystems.
Permafrost is emerging as a major issue under global change, permafrost stores massive amounts of carbon that now threaten to be released with climate warming. The research of Merritt Turetsky, an Integrative Biology professor in the Biological Resilience Network, focuses on how climatic disturbances like wildfire and permafrost thaw are affecting plant ecology, ecosystem carbon and nutrient cycling, and greenhouse gas fluxes in the Arctic and Boreal regions of Alaska and northwestern Canada.
Regeneration of exhumed Little Ice Age bryophytes. (2013). Catherine La Farge, Krista H. Williams, John H. England. Proceedings of the National Academy of Sciences, 110 (24) 9839-9844; DOI:10.1073/pnas.1304199110.