Effect of offshore oil platform structures on the distribution patterns of commercially important benthic crustaceans, with emphasis on the rock crab

Abstract

This work was conducted at Platform Holly, located in the Santa Barbara Channel, southern California.

From Objective: "1) Test whether commercially important crab species occurred in higher
densities beneath a platform compared to adjacent soft bottom; 2) characterize spatial and
temporal patterns of crab recruitment to a platform, including the importance of the platform
invertebrate community as potential habitat and source of food for crabs; and 3) evaluate our
data in the context of the four scenarios described above that reflect different combinations of
recruitment, and of distribution and abundance of mobile species around oil platforms."

From Significant Conclusions: "Three species of Cancer (Cancer antennarius, C.
anthonyi, C. productus) and the majid crab, Loxorhynchus grandis, were caught in traps
deployed on the bottom. None of the crab species clearly fit the recruitment/emigration
scenario. Although Cancer antennarius recruits to the platform, emigration of this species
from the platform appears limited. There was no evidence of large scale movement of this
crab from the platform into the surrounding soft bottom habitat and a behavioral preference
for hard substrate may preclude such movement. C. anthonyi most closely fits the attraction
scenario with movement between the platform and surrounding habitat. The attraction of
primarily female C. anthonyi to the platform during the winter and spring months, may
involve seasonal changes in habitat use related to reproduction; behavior that has not been
invoked previously to explain patterns of aggregation around artificial structures. The
distribution and abundance of C. productus and L. grandis most closely fit the visitor
scenario. C. productus is present in low densities throughout the year while L. grandis is
present seasonally. Our results, in the context of these scenarios, reflect interspecific
differences in patterns of abundance, recruitment, and behavior, and illustrate the need to
consider the responses of individual species to artificial structures such as oil platforms."