Fucal Matters: Composition and Diversity of the Understory Assemblages at the Upper and Lower Limits of Canopy-Forming Fucus distichus zone

Abstract

Fucus distichus is a canopy-forming seaweed that plays a key role creating habitats in the intertidal for small invertebrates and other understory algae. These habitats are important in influencing the composition and diversity of intertidal assemblages. It has been proposed that climate change and its consequential effects on the intertidal will likely alter the vertical distribution of F. distichus which could then affect the composition and diversity of the assemblages that rely on its canopy for survival. We compared the invertebrate and algal assemblages living under the F. distichus canopy between the upper and lower limits of the F. distichus zone to compare their composition and diversity. Our findings reveal a significant difference in assemblage composition across two zonal heights at the three sites we sampled at. Our results suggests that the potential shifts in F. distichus may have a negative effect on the diversity of the understory assemblages and force a homogenization of the intertidal community.