Succession and the Role of Ophiuroids as it Applies to the Marine Infaunal Associations off Palos Verdes, California

Abstract

Based on literature and data from monitoring surveys throughout the <br /><br />Southern Cahfomia Bight and especially off Palos Verdes, the pattern and rate of <br /><br />succession of ophiuroid populations of a previously perturbed (ocean outfall) area <br /><br />is assessed. Pre-discharge population levels of ophiroids off Palos Verdes were <br /><br />generally low, and between the early 1950's and 1970's densities were near zero. <br /><br />From 1972 to 1992 the number of ophiuroid species and densities have increased <br /><br />towards the center of the shelf and the zone of initial dilution (ZID), previously <br /><br />impacted by the effects of outfall. Even after natural mass mortalities, resettlement <br /><br />of ophiuroid populations is very slow, mainly due to adult migration rather than <br /><br />larval recruitment. In turn, the presence of high densities of adult populations <br /><br />favors settlement and metamorphosis of larvae. Conditions suitable for promoting <br /><br />and maintaining critical levels of adults represent the Catch-22 of larval recruit- <br /><br />ment, and hence successful resettlement of a previously perturbed area. Regard- <br /><br />less, conditions for infaunal benthos in general, and ophiuroids in particular, <br /><br />continue to improve off the Palos Verdes outfall as resettlement progresses.