I set up a field experiment to quantify how herbivory influences growth, by attaching small bull kelp (stipe length <30 cm) to concrete blocks and providing different levels of protection using plastic mesh: uncaged, partially caged (top and two sides), fully caged, and fully caged with a kelp crab (Figure 6). I deployed the blocks near Point Caution on San Juan Island for two weeks and measured the mass,
stipe
length, and blade length of the bull kelp at the beginning and end of the experiment. My results showed that juvenile bull kelp
grow
much more successfully when protected (fully enclosed in a cage) from large consumers like kelp crabs and urchins. The kelp enclosed in a cage with a crab
were
almost fully consumed, demonstrating the magnitude of damage these grazers can cause, especially to juvenile bull kelp.
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