Cryoconite holes

Cryoconite holes are water-filled reservoirs in the surface of glacial ice. The bottom of the cryoconite holes is usually filled with a thin layer of dark, biogenic sediment known as cryoconite. The formation of cryoconite holes results from sediments (cryoconite: fine rock fragments and mineral dust along with cryophilic organisms) that absorb solar radiation and so melt into the ice. Cryoconite holes are formed in the ablation zone of the glacier where the surface glacier ice is snow-free in the summer season. The diameter of cryoconite holes ranges from a few centimetres to even meters. Cryoconite holes are known as biodiversity hotspots on glaciers, biogeochemical factories recycle nutrients. As supraglacial biodiversity hotspots host a myriad of inhabitants ranging from microbes (bacteria, algae, fungi) to micro-invertebrates, such as tardigrades and rotifers, which dominate cryoconite holes worldwide and play the role of the apex consumers. Owing to their morphology, these holes serve as temporary sediment sinks, where mineral and organic particles (also anthropogenic contaminants) are deposited because of atmospheric fallout, and due to both abiotic and biotic processes on ice.
Cryoconite holes are inhabited by unique organisms that live exclusively on the ice surface. Global warming and shrinking of ice masses influence the disappearance of cryoconite holes, habitat loss, and threaten cryoconite holes’ biodiversity.