Figure 1.
Diagram of trophic interactions in our study system.
Diagram of trophic interactions among native red rock crabs, Cancer productus, two species of invasive oyster drill, Urosalpinx cinerea and Ocenebra inornata, and two oyster species, native Ostrea lurida and non-native Crassostrea gigas. Solid lines represent direct interactions, dashed lines indirect interactions with all arrows pointing in the direction of the trophic effect.
Figure 2.
Crab feeding rates and preference on native and non-native oysters.
Number (mean ± SE) of oysters consumed by crabs over 24 hours in the oyster preference experiment. Gray bars are Crassostrea gigas, Pacific oysters, and white bars are Ostrea lurida, Olympia oysters. Crabs were randomly assigned to one of three treatments (n = 12): (1) 25 C. gigas only, (2) 25 O. lurida only, or (3) the treatment labeled “Choice”, 25 C. gigas and 25 O. lurida.
Figure 3.
Crab feeding rates and preference on oyster drills and Crassostrea gigas.
Number (mean ± SE) of prey consumed by crabs over 24 hours in the drill/oyster preference experiment. Black bars are Crassostrea gigas, Pacific oysters, gray bars are Ocenebra inornata, Japanese drills, and white bars are Urosalpinx cinerea, Atlantic drills. Crabs were randomly assigned to one of four treatments (n = 14): (1) 25 C. gigas only, (2) 25 Ocenebra inornata only, (3) 25 Urosalpinx cinerea only, or (4) the treatment labeled “Choice”, 25 C. gigas, 25 O. inornata, and 25 U. cinerea.