Variations of Tardigrade Assemblages in Dust-Impacted Arctic Mosses

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Abstract
Differences in the species of bryophytes (mosses) and their tardigrade (water-bear) inhabitants in tundra adjacent to the trans-Alaska [USA] Pipeline haul road (now the Dalton Highway) are associated with environmental perturbations induced by the presence of the road, primarily road dust. Vehicular traffic on this gravel road generates a calcium-rich mineral dust that is windblown onto the tundra and is considered among the road''s most significant environmental impacts. Sphagnum mosses rarely occur within 10 m of the road, where dustfall is greatest. Sphagnum specimens (S. lenense, S. balticum, S. rubellum, and S. aongstroemii) were collected in transects paralleling the road at 50 and 500 m. Roadside moss samples are dominated by species tolerant of high calcium and drier habitats (e.g., Aulacomnium turgidum, Dicranum angustum). Tardigrade species dwelling within these mosses are typical of more xeric environments (Diphascon Scoticum and Hypsibius dujardini). While these fungivorous and algal feeding species numerically dominate roadside mosses, areas farther from the road are dominated by omnivores and carnivores (Macrobiotus hufelandi and M. harmsworthi, respectively).