Herbivory and community organization on a subtidal cobble bed
Date
2009Author
Scheibling, Robert Eric
Kelly, Noreen E.
Raymond, Bruce G.
Metadata
Show full item recordAbstract
We examined the role of molluscan mesograzers (periwinkles Littorina littorea, limpets
Testudinalia testudinalis and chitons Ischnochiton ruber) in mediating macroalgal succession after a
mass mortality of sea urchins Strongylocentrotus droebachiensis in a subtidal cobble bed in Nova
Scotia, Canada. Experimental exclusions of mesograzers from cobbles encrusted with smooth
(Phymatolithon) or rugose (Lithothamnion) coralline algae resulted in the establishment of a variety
of ephemeral filamentous algae, suggesting that these small (2 to 5 mm) but abundant herbivores are
the dominant agents controlling early succession and community organization in this habitat. In
removing inhibitive effects of early successional species, molluscan grazing facilitated the
establishment of fleshy perennial species Fucus evanescens and Chondrus crispus, which occasionally
escaped grazing at small size to attain a growth refuge on the cobbles. Algal biomass and species
richness were greater on Lithothamnion than Phymatolithon, suggesting that rugose crusts provide
more favourable microhabitats for recruitment or survival of various macroalgae. The distribution of
mesograzers differed between coralline types, likely influencing the rate and intensity of grazing:
periwinkles foraged on both types of crust, whereas limpets Occurred primarily on Phymatolithon and
chitons on Lithothamnion. All non-coralline algae were consumed when urchins were experimentally
reintroduced to the cobble bed, returning the assemblage to the urchin barrens state.
Citation
Scheibling, Robert E., Noreen E. Kelly, and Bruce G. Raymond. 2009. "Herbivory and community organization on a subtidal cobble bed." Marine Ecology Progress Series 382: 113-128. doi:10.3354/meps07965