Interactions between wave action and grazing control the distribution of intertidal macroalgae
Journal article, 2006

Canopy-forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave-induced forces and grazing for the recruitment and Survival of the canopy-forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long-term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7-8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or prune Fucus spp. larger than similar to 10 cm, while dislodgment was highly unlikely on the landward side for all sizes. Experimental transplantation of Fucus spp. supported the biomechanical analysis but also suggested that mechanical abrasion may further limit survival in wave-exposed locations. Experimental removal of the limpet Patella vulgata, which was the principal grazer at this site, resulted in recruitment of Fucus spp. on the seaward side. We present a model of limpet grazing that indicates that limpet densities > 5-20 individuals/m(2) provide a proximate mechanism preventing establishment of Fucus spp., whereas wave action > 2 m/s reduces persistence through dislodgment and battering. In a conceptual model we further propose that recruitment and survival of juvenile Fucus spp. are controlled indirectly by wave exposure through higher limpet densities at exposed locations. This model predicts that climate change, and in particular an increased frequency of storm events in the northeast Atlantic, will restrict fucoids to more sheltered locations.

wave exposure

dislodgment

SURVIVAL

Fucus spp.

PHYSICAL DISTURBANCE

transplantation

limpets

climate change

breaking waves

DISLODGMENT

hydrodynamic drag

CANOPY

SURF-ZONE

grazing

WATER MOTION

breakwaters

FUCUS-GARDNERI

Ulva sp.

LIMPET PATELLA-VULGATA

COMMUNITIES

Patella vulgata

ROCKY SHORES

Author

Per R. Jonsson

University of Gothenburg

Lena Granhag

University of Gothenburg

P. S. Moschella

Per Åberg

University of Gothenburg

S. J. Hawkins

R. C. Thompson

Ecology

0012-9658 (ISSN) 19399170 (eISSN)

Vol. 87 5 1169-1178

Subject Categories

Ecology

Biological Sciences

DOI

10.1890/0012-9658

PubMed

16761596

More information

Created

10/10/2017