Date of Award

Summer 1994

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Cynthia M. Jones

Committee Member

Ralph Stevens

Committee Member

Mark Butler

Committee Member

Mark Chittenden, Jr.

Call Number for Print

Special Collections LD4331.B46 W434

Abstract

Based on three years of data collection on the periodicity of the spawning run, the gonadosomatic index (GSI), and gonad histology, the spawning season for Chesapeake Bay black drum was found to be significantly shorter and later compared to populations from Florida and the Gulf of Mexico. The GSI is maximal in early April when black drum first enter the Chesapeake Bay region in contrast to data from Florida where GSI peaks during February and March. I confirm that black drum from the Chesapeake Bay are batch spawners. These results match those found for populations of black drum in the Northern Gulf of Mexico (Nieland and Wilson 1993). Batch fecundities were obtained using counts of hydrated oocytes in histological sections (mean = 1,286,280; n = 7). Microscopic morphometric measurements were made on ovarian histological sections and biases normally encountered with histological estimation of nuclear populations were eliminated with a function found in Abercrombie (1946). Volumetric sampling of hydrated oocytes was another method used to estimate fecundity (mean = 949,516; n = 3). Counts of hydrated oocytes within histological sections was the method best suited for this study. Using volumetric displacement the specific gravity of 27 late maturing spot, Leiostomus xanthurus, ovaries was determined to be 1.055.

A quantitative study was also preformed to determine the best of three fixation and two staining procedures for the examination of teleost ovarian tissues. Five structures were independently evaluated for stain and structural quality after having been fixed in 10 % formaldehyde, 2.5 % glutaraldehyde / 2.5 % formaldehyde, and Bouin's, and stained with hematoxylin and eosin Y (H&E) and periodic acid - Schiff and hematoxylin (PAS - hematoxylin). This study is designed for the nonhistochemist to establish the best combinations of fixatives and stains to make ovarian staging easiest. Stain quality was evaluated by assessing the contrast and clarity of ovarian structures. Structural quality was assessed by determining degree of damage to tissue components. Formaldehyde with H&E was determined to be the best combination for yolk globules (p < 0.01). Formaldehyde with PAS - hematoxylin was determined to be the best combination for nongerminal tissues (p < 0.01). H&E with either formaldehyde or glutaraldehyde / formaldehyde were found to be the worst combinations of stains and fixatives ( p < 0.01) for the evaluation of zona radiata. I recommended the use of formaldehyde and H&E for general ovarian staging.

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DOI

10.25777/epas-y865

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