Date of Award

Spring 1987

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Harold G. Marshall

Committee Member

Raymond W. Alden

Committee Member

James F. Matta

Committee Member

William M. Dunstan

Call Number for Print

Special Collections LD4331.B46 O73


This study was designed to evaluate short-term temporal and spatial components of phytoplankton variability within a tidal estuarine system, in reference to natural changes in the local environment.

Multiple water samples were collected weekly from October to December 1984 at 4 stations in different branches, or sections, of the Elizabeth River. Collection of chlorophyll~ data was structured to fit an analysis of variance, while the phytoplankton species and their environmental relationships were analyzed using multivariate techniques.

Lower chlorophyll a concentrations from 0.75 to 2.87 ug/1 were characteristic of the Main Stem and Southern Branch, while higher values of 1.27 to 22.58 ug/1 were in the Western and Eastern Branches. Results indicated that distances of from 6 to 14 km between stations had a greater effect on biomass variability than daily or weekly changes in the physico-chemical environment. Slack water conditions also had a significant (pa distributions, with higher values associated with slack-before-flood, or low water conditions.

The phytoplankton was dominated by diatoms (e.g. Skeletonema costatum), pico-nanoplankton and cryptomonads. Total abundance was greater in October than December, and was higher in the Eastern and Western branches, which were identified as the high biomass areas. Biomass estimates based on cell volume were greater during December, which corresponded to an increase of diatoms.

Results from cluster analysis revealed a similar temporal separation of environmental and phytoplankton species abundance samples. Samples collected in October and December were more dissimilar than samples collected from the 4 sites. canonical variate analysis suggested that different groups and abundance levels of phytoplankton species corresponded to different ranges of environmental conditions in the River. The six week period between collections had a greater influence on species abundance patterns than mesoscale spatial lengths of from 6 to 14 km.


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