Experimental warming of bryophytes increases the population density of the nematode <i>Plectus belgicae</i> in maritime Antarctica

Abstract

Abstract Despite nematodes routinely being the most frequent soil- and bryophyte-associated animals in maritime Antarctica, there is a lack of clarity about the influence of warming on their populations in the region. Here, we report the results of a field experiment on Adelaide Island that tested the effects of warming with open-top chambers (OTCs) for 37 months on nematodes associated with the bryophytes Cephaloziella varians and Sanionia uncinata . Over the experiment's duration, OTCs increased the population density of the nematode Plectus belgicae in mats of both bryophytes by six-fold, with four- to seven-fold increases in the abundances of male, female and juvenile P. belgicae in warmed mats, and with the largest effects on the abundances of juveniles. Despite C. varians , which is black in colour, warming to a greater extent than S. uncinata during summer, no interactive effects of OTCs and bryophyte species were recorded on the population density of P. belgicae . Our results corroborate a previous study showing that warming increases Plectus population densities in maritime Antarctic soils, with implications for the region's terrestrial food webs.