Date of Award

Fall 1982

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Oceanography

Committee Director

Anthony J. Provenzano

Committee Member

Joseph H. Rule

Committee Member

Martin A. Buzas

Call Number for Print

Special Collections LD4331.O35P24

Abstract

Six variants of the highly variable foraminiferal species, Elphidium excavatum (Terquem) were recognized in the Crumps Bank and Willoughby Bank areas of the southern Chesapeake Bay. Measurements of the size of the test, the number of chambers, the number of umbilical bosses, and the number and average length of the sutural bridges on the last formed chamber, and opaqueness or translucence of the test were made on 30 specimens from each of 36 stations selected for differences in environmental parameters. The measurements were statistically analyzed by discriminant analysis to test the hypothesis that the variants are distinct morphotypes and to provide a quantitative measurement of the external characters by which these variants are distinguished.

Secondarily, these morphological measurements were compared statistically to the depth, temperature, salinity, pH, Eh, sediment texture and trace metal concentrations in the sediment at each station to determine if there is any environmental control on the variations in the study area.

From discriminant analysis of the data, it can be concluded that E. excavatum (Terquem) is a highly variable species consisting of only two distinct morphotypes, which, if necessary, can be distinguished on the forma level; E. excavatum (Terquem) forma clavata and E. excavatum (Terquem) form a selseyensis. Visual distinction of these two formae with a light microscope is usually not difficult, however, separation of the intergrading and overlapping specimens between the two end members can only be determined reliably by statistical analysis of measured characters. No acceptable correlation between morphological variation of the species and measured environmental factors was found in the study area.

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DOI

10.25777/jfpb-bz36

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