terrestrial 46 very low temperature 36 aquatic 24 ice 21 soil 17 fresh water 6 low salinity 4 anthropogenic 2 built environment 2 forest 2 lentic 1 littoral 1 lacustrine 1 plant host 1 rhizosphere 1 host-associated 1 stream 1 subsurface 1 groundwater 1 arid 1