Effects of Biota on Backscatter: Experiments with the Portable Acoustic Laboratory (PAL)
Abstract
This is a report of the field test of a "portable acoustic laboratory," a set of observational tools that can be used for in situ testing of the effects of organisms, biological processes, and benthic structures on underwater acoustic propagation in sediments. A test was conducted off the end of a pier at the Friday Harbor Laboratories of the University of Washington. A semicircular region of seabed was monitored for several weeks, then clean sand was spread over two muddy patches. Monitoring showed a sudden drop in backscatter, but this was short lived. Abundant mysid shrimp appeared to have caused microtopographic changes that quickly raised backscatter intensity to near-background levels. Subsequent introduction of burrowing thalassinid shrimp had the anticipated effect of enhancing backscatter above background and pre-sand-layer levels. It is anticipated that this kind of portable laboratory will be able to answer many specific questions about potential biological effects on backscatter. For example, how does the acoustic signature- of a mine-like object change as organisms foul the exposed surfaces? And, how does the acoustic coupling of such an object with overlying water and underlying sediments) change in the presence of bioturbation and geochemical processes?
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 03, 2003
- Accession Number
- ADA414899
Entities
People
- Christopher D. Jones
Organizations
- University of Washington