Glaciers and ice sheets as a biome

We had a lecture today about the cryosphere – the places on Earth where water is in its solid form – and glaciers and ice sheets were introduced as a biome. I found this idea particularly interesting and I was keen to discover a little bit more about it. So, I’ve done a bit of reading and here I’m going to share what I have found with you!

A biome is commonly defined as an area of the planet that can be classified according to the plants and animals that live in it. Temperature, soil, and the amount of light and water all help determine what life exists in a biome. The term itself is something I am familiar with but when I think of it I think of Tropical Rainforests and not glaciers and ice sheets.

When I think of the term 'biome' I think of Tropical Rainforests, not glaciers and ice sheets. Source: National Geographic

Alexandre M. Anesio and Johanna Laybourn-Parry argue that glaciers, ice sheets and the cryosphere are a biome uniquely dominated by microorganisms and active biogeochemical processes that have both local and global impacts. In their paper ‘Glaciers and ice sheets as a biome’, they say that it is time to recognise the cryosphere as one of Earth’s biomes.

The different habitats of the glacial biome

The ice surface

During the melting season, the presence of water provides habitats at the surface of the ice and snow. Distinct communities develop here comprising of species that are tolerant of low temperatures and able to overcome seasonal desiccation (Simon et al., 2009).

Subglacial environments
These habitats are a lot different from the ice surface environments for a number of reasons. Firstly they have a higher rock to water ratio that means the contact time between bedrock and water is much greater and secondly there is a lack of light, which tends to lead to the development of anoxic conditions. These environments dominated by heterotrophic and chemoautotrophic prokaryotes, as well as many fungal species.

Life within ice
Finally it is important to mention that a great deal of biological activity occurs within the ice itself. There are communities of algae, small animals and microbes all living inside the actual glaciers and ice sheets. This has been demonstrated by analysis of ice cores (e.g. Greenland Ice Project).

Ice core analysis has demonstrated that microbes and algae live inside the ice. Source: colorado.edu

Glaciers and ice sheets should be included as a biome
When I think of glaciers and ice sheets I don't picture much green nor many animals running around. However it is important to remember that these habitats support a high diversity of viruses and bacteria. Anesio and Laybourn-Parry (2012) suggest that this may be because a lot of microbial species are adapted to surviving and functioning under low temperature conditions. Despite this only a few studies have investigated the biodiversity of glacial habitats and where attempts have been made they have mostly been based on microscopic observations (e.g. Porazinska et al.,2004). 

The inclusion of glaciers and ice sheets as a biome with unique life adaptations would have wider implications for the conservation of these climate-sensitive ecosystems (Anesio and Laybourn-Parry, 2012). If these environments are not considered as one of Earth's biomes they may not receive the same conservation priority as other sensitive ecosystems. There will be global implications of this. For example the loss of biodiversity may lead to the loss of a pool of genes adapted to surviving and thriving in the cold. 

The loss of biodiversity from the cryosphere could lead to the loss of a pool of genes adapted to surviving in the cold. Source: travelsupermarket.com