Resilience of an intertidal infaunal community to winter stressors

Disturbances can greatly affect densities and richness of biological communities. Given the relatively severe winters in Atlantic Canada, including on mudflats in the Bay of Fundy, winter may be an important structuring force for intertidal infaunal communities. Further, stressors may include effects of sub-zero temperatures, temperature variations, wind, different types of ice, scour, and low sediment oxygen content. We sampled 8 major mudflats in the Bay of Fundy (a macrotidal, temperate system) before (December) and after (March) winter over 2 years, to quantify the biotic community as well as various environmental variables related to both sediment conditions and winter severity. Infaunal communities exhibited significant, but small changes over winter. Furthermore, patterns were not consistent among years, sites or taxa: some taxa decreased in density, others did not change, and a few increased. Finally, the over-winter community change was only weakly correlated to winter stressors. Analysis of the multivariate correlation indicated that physical disturbance of sediments (i.e., scour density and depth, variance in drift ice cover) and sediment oxygen content have the potential to influence community structure. Overall, winter (strictly defined as the period with ice present in our study) did not greatly influence the infaunal community, and the mudflat infaunal community appears resilient to winter stressors.