The temporal stability of aggregate community properties depends on the dynamics of the component species. Asynchronous species dynamics can maintain stability (i.e. invariability in aggregate properties) through temporal complementarities between species with different environmental tolerances. Few manipulative studies have, however, tested in natural conditions the response of this mechanism to multiple stressors. In field experiments we tested the separate and interactive effects of two stressors associated with storminess—loss of a canopy-forming species and mechanical disturbances—on species synchrony and community respiration of intertidal hard-bottom communities on Helgoland Island, NE Atlantic. Treatments consisted of regular removal of the canopy-forming seaweed Fucus serratus and a mechanical disturbance applied once at the onset of the experiment in March 2006. The level of synchrony in species abundances was assessed from estimates of species percentage cover every three months until September 2007. Experiments at two sites consistently showed that canopy loss significantly reduced species synchrony. Mechanical disturbance had neither separate nor interactive effects on species synchrony. Accordingly, in situ measurements of CO2-fluxes showed that canopy loss, but not mechanical disturbances, significantly reduced temporal variation in community respiration during emersion periods. Our results support the idea that compensatory dynamics may stabilise aggregate properties. They further suggest that the ecological consequences of the loss of a single structurally important species may be stronger than those derived from smaller-scale mechanical disturbances in natural ecosystems.