Date of Award

Spring 2002

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Harold G. Marshall

Committee Member

Kneeland Nesius

Committee Member

Lewis Affronti

Call Number for Print

Special Collections LD4331.B46 W433 2002


Autotrophic picoplankton and phytoplankton composite samples were collected from the surface, pycnocline, and bottom water layers at three stations in the lower Chesapeake Bay between June and September 1993. Using light microscopy a total of 170 phytoplankton taxa were identified. Utilizing epifluorescent microscopy, the picoplankton taxa were distinguished by size, representing species with cells less than 2 microns. Diatoms were the dominant taxa during this period, with lesser representation by the other phytoplankton components. Within the picoplankton category, cyanobacteria were dominant. Statistical analyses of the data indicated the vertical composition and abundance of the phytoplankton was not significantly different over the vertical range of depths. Species diversity was high and phytoplankton densities were similar at all three stations. A Principal Component Analysis clustered the pycnocline waters together, separate from both the surface and bottom waters. Variation in the density of the picoplankton did not differ significantly at the three depths sampled. It is suggested that the variability of the phytoplankton composition, combined with the relatively small sample size, may have masked any statistically significant differences between the three stations, and that with increased sampling, differences in the spatial and seasonal species composition within the pycnocline of the lower Chesapeake Bay may be identified.


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