Cryoconite: Dark Biological Secrets of the Cryosphere

Recently, Tris Irvine-Fynn, Arwyn Edwards, Nozomu Takeuchi and I put together a big review paper detailing the past century and a half of cryoconite research. Here’s a brief run-through…

What is cryoconite?

Cryoconite refers to granules comprising organic and inorganic matter that are formed due to biological activity on ice surfaces. In the paper we go into detail regarding the amounts and types of both inorganic and organic materials found in cryoconite granules and comment on geographic variability. Cryoconite granules can vary in size from sub-mm to >1 cm. We examine the likely controls on granule formation and growth and comment upon the glaciological and ecological significance of aggregation.

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A cryoconite-rich environment on the Greenland Ice Sheet

Cryoconite Holes

Cryoconite can be found in a wide range of supraglacial environments, but the most frequent is the classic cryoconite hole. We review in detail the mechanism of hole formation and development and discuss potential feedbacks between hole shape and microbial ecology, in particular the notion that hole development may represent a form of habitat-scale ecosystem engineering.

Cryoconite Biology

Cryoconite holes are sites of high microbial diversity and rates of activity in the supraglacial zone; however, the structures and functions of microbial communities in cryoconite changes over space and time. We explore these changes in detail, firstly by reporting the species that have been identified in cryoconite holes worldwide and what is known of their origins, then examining their biogeochemical cycling and potential for influencing the quality and quality of exports to other glacial and extraglacial zones.

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Beautiful Greenland Ice Sheet cryoconite holes

Arctic, Antarctic and Lower Latitude Cryoconite

We then compare and contrast physical and biological properties of cryoconite and cryoconite holes from each polar environment and lower latitudes, finding cryoconite to share some global characteristics but also have other region-specific characteristics.

Cryoconite, Climate Change and Anthropogenic Pollution

The literature incorporating future climate scenarios into cryoconite science is reviewed along with those studies that examine the impact of anthropogenic pollutants on cryoconite and vice-versa.

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On Greenland ice pitted with cryoconite holes

Is Cryoconite Science Back Where It Started?

In this section we examine the contention that much of our current knowledge of cryoconite stems from the work of the early polar explorers, who had a remarkably advanced understanding of supraglacial microbiology.

Where Should Cryoconite Science Go From Here?

We finish by making suggestions for future research, advocating the integration of wider glaciological processes into our understanding of cryoconite and vice-versa. This echoes our recent work on ‘biocryomorphology’ (see here and here) which calls for a more holistic understanding of the cryosphere, including cryoconite as an important component.

The paper is available here!

We also suggest these review papers that consider broader aspects of life in the cryosphere:

Hodson et al. (2008) Glacial Ecosystems, Ecological Monographs

Stibal et al. (2012) Biological processes on Glaciers, Nature Geoscience

Hodson et al. (2015) Cryospheric ecosystems: a synthesis of snowpack and glacial research, Environmental Research Letters

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Biocryomorphology

In a recent publication in Frontiers in Earth Science, Arwyn Edwards, Alun Hubbard and I outlined a framework for developing a more holistic understanding of the cryosphere. We suggest that the complex reciprocal relationships between physical and biological processes on ice surfaces represent a crucial gap in our knowledge of glacial systems, and propose to study them under the term ‘biocryomorphology’. The rationale for this terminology is that it is analogous to biogeomorphology –a well-established research theme focused upon biotic-abiotic interactions in terrestrial environments.

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Cryoconite: We suggest that there is still a lot to learn about these supraglacial melt features

We identify cryoconite holes as important biocryomorphic entities, especially since cryoconite science is now mature enough to incorporate complex concepts such as coevolution of ice surface topography, hydrology, hole shape, size, position and microbial communities. The figure below outlines what we consider to be priority areas for biocryomorphic research.

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Our outline of key biocryomorphic knowledge gaps and some suggested techniques for addressing them… (from Cook et al. 2015)

We propose that biocryomorphology should be established as a concept embedded within glaciology that integrates hydrology, topography, surface roughness and microbial ecology. We hope that this suggestion stimulates research into more complex, reciprocal ice-microbe interactions.

The full paper is available to download here:

http://journal.frontiersin.org/article/10.3389/feart.2015.00078/full