Rapid recovery of fauna following simulated ice rafting in a Nova Scotian seagrass bed

Abstract

The shallow portion of Zostera marina bed in Pomquet Harbour is subject to patchy disturbance by ice rafting, in which areas of seagrass are frozen into the underside of ice, which breaks up into large pieces and floats away. Ice rafting was simulated by clearing 1.2 × 0.4 m patches in the spring. Eelgrass recovery on cleared patches was relatively slow, and 4 mo later the biomass was still significantly lower on the cleared patches than in the surrounding seagrass bed. Recovery of macroalgae was much more rapid, biomass approximating control levels 1.5 mo after disturbance. Clearing also had a relatively short-lived effect on most invertebrate species, numbers of all species on the cleared patches being at or above those in the surrounding seagrass bed 3-4 mo after clearing. Recovery of epifauna was significantly linked to macroalgal biomass on cleared patches, indicating that the rapid return of macroalgae to cleared patches enabled this community to recover rapidly after disturbance despite the slower seagrass recovery. -from Authors