Publication Date

1979

Document Type

Dissertation/Thesis

First Advisor

Johnson, Robert Karl

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences

LCSH

Vinciguerria nimbaria; Photichthyidae; Vinciguerria lucetia; Fishes--Pacific Ocean

Abstract

Vinciguerria lucetla, a mesopelaglc photichthyid, is endemic to the eastern tropical Pacific and there replaces the widespread, nearly circumtropical, V. nimbaria. A comparison of morphological features was made between 808 adult specimens of V. lucetia and 391 V. nimbaria in the Pacific Ocean. Significant differences exist between the two species in gill raker counts, spacing and length of gill rakers, photophore counts, and caudal peduncle depth. Only gill raker counts give complete separation between these two species, V. lucetia possessing 26 to 36 rakers on the first gill arch, and V. nimbaria 18 to 24. The eastern Pacific distributions of V. lucetia and V. nimbaria are described. Westward extensions in the range of V. lucetia are closely associated with the North and South Equatorial currents, whereas poleward extensions appear to follow currents along the coast of North and South America. Circumscribing the range of V. lucetia is the extent of the oxygen minimum core with levels of 0.5 ml/l or less. Intrusions of V. nimbaria into the eastern Pacific are associated with the presence of more highly oxygenated waters. Specimens from throughout the range of V. lucetia were examined for intraspecific variation. Discriminant analysis and clustering computer programs were utilized in this, and in the interspecific study. Variation is greatest between longitudinal zones, with greatest diversity at the north and south extremes. Some meristic characters are negatively correlated with productivity and temperature. Upper jaw length is negatively correlated with productivity. The zonal nature of the variability is probably due to these correlations.

Comments

Includes bibliographical references.||Includes illustrations and maps.

Extent

viii, 171 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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