Authors: Fenstermacher L. E.; Crawford G. B.; Borgeld J. C.; Britt T.; George D. A.; Klein M. A.; Driscoll N. W.; Mayer L. A.

Source: Marine Georesources and Geotechnology, Volume 19, Number 2, 1 April 2001 , pp. 135-145(11)

Publisher: Taylor and Francis Ltd

Abstract:

Detailed acoustic surveys of benthic sediments were conducted in July 1995 and September 1998 in the vicinity of Humboldt Bay, California. During these surveys, a band of enhanced acoustic backscatter was observed offshore from the bay entrance, approximately parallel to the isobaths, in water depths ranging from 16-24 m. In order to assess the cause of the increase in backscatter levels, a more comprehensive study was conducted in August and September 1999 using 100 kHz side-scan sonar, bottom grab sampling and underwater video recording. New observations indicated that a dense population of sand dollars (Dendraster excentricus) coincided with the enhanced backscatter band. Compared to the two previous acoustic studies, the central section of the band expanded westward by 180 m and the southern section of the band shifted eastward by 160 m, possibly resulting from a change in the biological or physical factors which influence the location and breadth of sand dollars. The relationship between high sand dollar abundance and enhanced acoustic backscatter was further verified in the nearshore region off Samoa Beach California, where a dense, banded population of sand dollars was previously observed. Video footage confirmed the presence of a band of sand dollars, also nominally parallel to the isobaths, in water depths of 8–15 m. A band of enhanced backscatter coincided with the dense sand dollar population. The identification of dense aggregations of sand dollars through enhanced acoustic backscatter could lead to the use of acoustic techniques to study sand dollar distributions and abundance.

Keywords: ACOUSTICS; BIOACOUSTICS; BACKSCATTER; MAPPING; NEARSHORE; ENVIRONMENTS; SAND; DOLLARS; SIDE-SCAN; SONAR

Language: English

Document Type: Research article

Publication date: 2001-04-01

More about this publication?

• Information for Authors
• Subscribe to this Title
• ingentaconnect is not responsible for the content or availability of external websites

Related content

• In this: publication
• By this: publisher
• In this Subject: Geology ,  Mining & Metallurgy
• By this author: Fenstermacher L. E. ;  Crawford G. B. ;  Borgeld J. C. ;  Britt T. ;  George D. A. ;  Klein M. A. ;  Driscoll N. W. ;  Mayer L. A.

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers