Treatments consisted of an open plot (0.25 m2) marked by 4 stakes
(=natural control), a partial cage (=cage control), and cages stocked
with H. sanguineus between 7 and 26.9mmCWat densities representative
of the field site (=1X), double the natural density at the site
(=2X), or without H. sanguineus (=0X). Cages at normal and double
field densities were stocked with H. sanguineus at densities and sizes
reflecting numbers found in surveys at the site before each experiment.
Each block (n=5) contained one replicate of each treatment randomly
arranged in a linear fashion parallel to the shore, with each experiment
running along 64–67mof shoreline. Each experimentwas conducted in
undisturbed intertidal areas.