Date of Award

Summer 1977

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Harold G. Marshall

Committee Member

Jame F. Matta

Call Number for Print

Special Collections LD4331.B46 C654


Phytoplankton samples were collected monthly (August 1974-June 1975) at two stations in the Back Bay system of southeastern Virginia. Measurements of phytoplankton productivity and potentially influencing environmental parameters (water and air temperature, turbidity, depth, pH, salinity, dissolved oxygen) accompanied sample collections. A total of 106 phytoplankton species, representing six algal divisions and 54 genera were identified. Cyanophyta species were dominant at both stations in the warmer months of August, September, October, and June, and in April at one station only. In all remaining months, Chlorophyta species were dominant, indicating a seasonal shift in phytoplankton composition during winter and spring. The absence of dominance by diatoms at any time during the study indicated a clear departure from typically estuarine conditions. A predominantly fresh water flora favored comparison of data with studies conducted in southeastern Coastal Plain lakes and ponds. Seasonal variation in phytoplankton density followed a bimodal pattern at both stations, with moderate increases in October, and density maxima in March and April. Phytoplankton productivity values correlated significantly with standing crop, but not with measurements of individual environmental parameters. Productivity values were similar to values measured in other shallow, upper-estuarine habitats. Seasonally elevated productivity values and associated populations of green and blue-green algae suggested advanced mesotrophic, or eutrophic conditions such as reported in nutrient-enriched Coastal Plain ponds.


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