Spiny Lobster (Panulirus interruptus) Use of the Intertidal Zone at a Santa Catalina Island MPA in Southern California
Abstract
This study investigated spiny lobster (Panulirus interruptus) use of the intertidal habitat as an important and underappreciated foraging ground during the reproductive season, and the spatial scales over which lobsters interacted with this habitat at two locations off Santa Catalina Island, California. At Bird Rock and Big Fisherman Cove, there were significantly higher densities of lobsters within the intertidal zone at night compared to the adjacent subtidal zone, as well as a higher density of reproductively active (eggcarrying) females, suggesting the non-trivial use of this habitat. Spiny lobster density, size, sex ratio (in favor of females), and reproductive condition were also higher at Bird Rock, reflecting differences in the underlying intertidal habitat composition between locations. Percent cover of the California mussel (Mytilus californianus) exhibited a significant positive correlation with lobster density, and the elevated abundance of this preferred prey item might explain the enhanced lobster population metrics at Bird Rock. In addition, the spatial distribution of mussels on Bird Rock followed a clumped distribution with discrete patches at a sub-meter scale, which may influence the spatial scale of spiny lobster foraging behavior. The results of this study highlight a critical new dimension of spiny lobster management throughout Southern California, encouraging the consideration of the intertidal zone and the effects of prey distributions on foraging behavior.