Emergence of burrowing urchins from California continental shelf sediments: A response to alongshore current reversals?

Estuarine, Coastal and Shelf Science
By: , and 

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Abstract

Two sequences of bottom photographs taken every two or four hours for two months during the Coastal Ocean Dynamics Experiment (CODE) off the Russian River, California, reveal the dynamic nature of interations between the water column, the sediments, and benthic organisms in the mid-shelf silt deposit.

Time-lapse photographs taken between late spring and early summer in 1981 and 1982 show that the subsurface-dwelling urchin Brisaster latifrons (one of the largest invertebrates found in shelf-depth fine sediment off the U.S. Pacific coast) occasionally emerged from the sediment, plowed the sediment surface during the course of a few hours to several days, then buried themselves again. Frame-by-frame study of the film sequences shows that the urchins typically emerged following relaxation of coastal upwelling, periods characterized by current direction reversals and increases in bottom water turbidity.

Among the possible causes of the emergence of urchins and the consequent bioturbation of the upper few cm of sediment, a response to an enhanced food supply seems most plausible. Circumstantial evidence suggests the possibility that phytoplankton sedimentation during periods of upwelling relaxation could provide a new source of food at the sediment surface.

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Publication type Article
Publication Subtype Journal Article
Title Emergence of burrowing urchins from California continental shelf sediments: A response to alongshore current reversals?
Series title Estuarine, Coastal and Shelf Science
DOI 10.1016/0272-7714(89)90006-1
Volume 29
Issue 2
Year Published 1989
Language English
Publisher Elsevier
Description 12 p.
First page 171
Last page 182
Country United States
State California
Other Geospatial Pacific Ocean, Russian River
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