MEPS 381:183-187 (2009)  -  DOI: https://doi.org/10.3354/meps07935

ABSTRACT: We investigated the potential utility of intertidal barnacles as ecological indicators of the intensity of ice scour on the Gulf of St. Lawrence coast of Nova Scotia, Canada. This coast is extensively covered by sea ice in winter. Shortly after ice melt, between May and June 2007, we quantified the density of adult barnacles Semibalanus balanoides in the high intertidal zone in 8 rocky locations distributed along nearly 25 km of coastline. At each location, we took measurements in 2 types of habitat that differ in ice scour intensity: habitats facing open waters, where ice scour is intense, and habitats facing a rocky land mass between a few meters and 10s of meters away, where ice scour is moderate. Adult barnacle density was significantly higher in sheltered sites than in exposed sites by a factor of 3, on average. Ice scour intensity is likely the main factor determining such a pattern, as we previously found that barnacle recruitment is similar in both types of habitat and that the potential competitors (algae and mussels) and predators (whelks) are virtually absent in the high intertidal zone. Thus, high-intertidal barnacles might serve as indicators of differences in ice scour intensity among coastal sites in our region. Future studies should determine the spatial scales of applicability of this approach.

KEY WORDS: Barnacle · Ecological indicator · Ice scour · Intertidal zone · Sea ice