Date of Award

Fall 1994

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Harold G. Marshall

Committee Member

Raymond W. Alden III

Committee Member

Kneeland K. Nesius

Call Number for Print

Special Collections LD4331.B46 D38


A two year study of the mesozooplankton composition and seasonal distribution was conducted in the Pagan River, a nutrient rich tidal estuary and tributary to the lower James River. The mesozooplankton was dominated by calanoid copepods (80%), with the total zooplankton abundance peaks occurring during spring and fall. The total mean abundance, 3008/m', was somewhat lower than those found by other authors, however the mean abundance at one station approximated those means. Seventy-eight percent of the calanoid copepods were Acartia spp. that were primarily responsible for the fall increase in mesozooplankton abundance. The spring increase was primarily due to increases in Eurytemora affinis which overall was 17% of total abundance. The remaining total abundance (20%), other than calanoid copepods, included 8% Uca zoea, 6% barnacle nauplii and 1% Harpacticus gracilis. Fish larvae and decapod crab zoea were abundant in summer months.

The Pagan River is a shallow tidal estuary, with waters ranging from mesohaline to fresh water, and is subject to periods of low oxygen concentrations, high turbidity and also has relatively high concentrations of nitrogen and phosphorus compounds. The effects that may be associated with the higher concentrations of nitrates and phosphates at the upstream stations are obscured by species preference for particular seasonal and/or salinity conditions.


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