DISTRIBUTION PATTERNS OF TETRAPYGUS-NIGER (ECHINODERMATA, ECHINOIDEA) OFF THE CENTRAL CHILEAN COAST
No Thumbnail Available
Date
1993
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
We investigated spatial distribution and temporal occurrence patterns of Tetrapygus niger in the subtidal zone off the central Chilean coast from March to November 1990. The shallowest portion of the subtidal zone and the shallowest edge of the kelp forest of Lessonia trabeculata appeared to be important recruitment zones for this species. We found a significant number of recruits along the bed border, and a marked decrease of urchin abundance toward the center of the kelp. Data obtained in September and November outside the kelp bed showed juvenile urchins [i.e. <24 mm test diameter (TD)] strongly associated with crevices. Size-frequency distributions at 2 m depth for those months also showed a large trough of intermediate-sized individuals (i.e. 15 to 30 mm TD). Temporal analysis of size-frequency distributions of individuals collected outside the kelp showed a relatively slow shift of modes between March and September and a major modal shift from September to November. Density values of urchins found in November were relatively low; however, the individuals appeared aggregated.