Disappearing Kilimanjaro snow—Are we the last generation to explore equatorial glacier biodiversity?

Abstract

Glaciation accompanied our human ancestors in Africa throughout the Pleistocene. Regrettably, equatorial glaciers and snow are disappearing rapidly, and we are likely the last generation who will get to know these peculiar places. Despite the permanently harsh conditions of glacier/snow habitats, they support a remarkable diversity of life ranging from bacteria to animals. Numerous papers have been devoted to microbial communities and unique animals on polar glaciers and high mountains, but only two reports relate to glacial biodiversity in equatorial regions, which are destined to melt completely within the next few decades. Equatorial glaciers constitute “cold islands” in tropics, and discovering their diversity might shed light on the biogeography, dispersal, and history of psychrophiles. Thus, an opportunity to protect biota of equatorial glaciers hinges on ex situ conservation. It is timely and crucial that we should investigate the glacial biodiversity of the few remaining equatorial glaciers.

Biological albedo reduction on ice sheets, glaciers, and snowfields

“…Invertebrates delivered by wind to cold, high-UV glacial ecosystems typically find the environment to be lethal (Edwards, 1987;Edwards and Banko, 1976;Heinrich and Bell, 1995;Swan, 1963). However, resident metazoans in the cryosphere do occur, including nematodes (Azzoni et al, 2015), rotifers (Shain et al, 2016), tardigrades (Zawierucha and Shain, 2019), and glacier ice worms (Dial et al, 2012;Hotaling et al, 2019a). Resident invertebrates are often present at high densities (hundreds to thousands per m 2 (Goodman, 1971;Mann et al, 1980) and tend to be highly melanized (see Fig.…”

“…A variety of temperate regions have also been overlooked, including subranges of the Rocky Mountains in North America (e.g., Teton Range, USA), the Caucasus Mountains in eastern Europe (e.g., Makowska et al, 2020), and similar localities. Rapidly receding tropical glaciers are also urgent targets for ecological studies (Veettil and Kamp, 2019;Zawierucha and Shain, 2019). Tropical glaciers, for instance, show far greater variability in terms of climate sensitivity (Kaser, 2001;Kaser et al, 2004) compared to mid-and high-latitude glaciers and differ from higher latitude glaciers by the absence of seasonal temperature cycles (monthly mean temperatures vary by less than 5ºC) and extended periods of freezing (Lentini et al, 2011).…”

The need for stewardship of lands exposed by deglaciation from climate change

“…Rabatel et al (2013) highlight the high vulnerability of tropical glaciers in the Andes located below 5400 m.a.s.l., which will probably disappear in one or two decades. Likewise, if current conditions persist, the East African and Australasian glaciers will disappear within the same timeframe (Mt Kilimanjaro: Thompson et al, 2009; Zawierucha & Shain, 2019; Puncak Jaya: Veettil & Wang, 2018). Globally, the complete extinction of 8–21 of the iconic World Heritage Glaciers is expected by the end of the century (Bosson et al, 2019).…”

Five animal phyla in glacier ice reveal unprecedented biodiversity in New Zealand's Southern Alps

“…Prior to compression, however, upper layers of ice (i.e., weathered surface and several metres below) maintain ultrastructural spaces between crystal interfaces, forming arrays of microchannels that connect with the glacial surface 3 , 4 . On maritime glaciers, those most threatened by our changing global climate 5 – 7 , ultrathin films of water fill these veinous aquifers and provide a microenvironment for extremophilic life. Permanently cold temperatures (0 °C and below), high UV radiation, nutrient-poor and hydrologically-limiting conditions constrain organismal diversity in this habitat to specialized psychrophilic taxa, predominantly single-celled microbes 8 – 11 .…”