Date of Award

Spring 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Harold G. Marshall

Committee Member

Rebecca Bray

Committee Member

G. Richard Whittecar

Call Number for Print

Special Collections LD4331.B46 K66 2001

Abstract

Five ephemeral ponds were identified in and around the Grafton Ponds Natural Area Preserve, approximately 56 km north of the City of Norfolk, Virginia. These ponds, which are filled seasonally by precipitation and groundwater discharge, range from 0.1 ha to 2 ha in size and from 4 cm to 3 meters in depth. Ponds for the study were chosen based on variations in their size, depth, basin cover material, canopy openness, and historical inundation period. The purpose of this study is to relate differences in the phytoplankton assemblages to the physical and chemical characteristics of the ponds. All five ponds followed the expected seasonal patterns for water temperature and depth, and maintained a stable acidity throughout 1999. There were 119 taxa identified, 36 of which were in all five ponds. Shannon Diversities ranged from 0.94 — 2.66. Bray-Curtis Dissimilarity values ranged from 3.8 — 54.3. The larger ponds were typically more similar to each other and the smaller ponds were typically more similar to each other. Three ponds exhibited seasonal patterns that were dominated by chlorophytes in the cooler months and cyanobacteria in the warmer months. Dinoflagellates dominated the fourth pond during the cooler months. The fifth pond maintained a diverse community year round. Cryptomonas erosa was predominant in all five ponds during the late summer.

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DOI

10.25777/dw4f-sw18

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