An ecological reconnaissance of the deep scattering layers in the eastern tropical Pacific
Authors
Dunlap, Calvin Ray, III
Subjects
Acoustics
Scattering
Biology
Biological oceanography
ASW
Scattering
Biology
Biological oceanography
ASW
Advisors
Haderlie, Eugene C.
Date of Issue
1968-06
Date
June 1968
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
This reconnaissance is the first ecological study of the deep scattering layers (DSL) in the eastern tropical Pacific. It was made during two three month cruises of the R/V TE VEGA, one of which was predominantly in the Gulf of California. The reconnaissance is based on over 100 fathometer echograms and 100 trawls which fished for a period of one hour with an opening and closing Tucker midwater trawl. Echograms of two fathometer frequencies (30 Kc and 11 Kc) indicated that two latitudinal scattering zones may exist. Temperature, oxygen, light intensity, faunal composition, and swimbladder morphology were investigated with relation to the DSL. The oxyclines associated with the eastern Pacific oxygen minimum zone seemed to have little effect on the DSL. Possible further evidence for the migration of DSL organisms for feeding purposes was apparent as the maximum night surface scattering was observed at the depth of maximum Chlorophylla or phytoplankton. Frequency comparisons indicated a possible gradient of the size of organisms in the DSL with smaller organisms toward the top of the layer. A twenty-four hour continuous observation of an equatorial Pacific DSL diurnal cycle and an evaluation of possible scattering organisms are included.
Type
Thesis
Description
Series/Report No
Department
Meteorology and Oceanography
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.