96 
Michael A. Mallin 
40 
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
Month 
■ Copepods 
£v.v»l Cladocerans 
1 I Rotifers 
Fig. 4. Percent composition of total zooplankton biomass by major taxa groups 
for Sutton Reservoir during 1985. 
biomass was composed mainly of Diaptomus dorsalis , Daphnia ambigua, 
B. coregoni, and Mesocy clops edax. 
Comparisons were made to determine if there were differences 
between the pelagic and near-shore zooplankton communities. The trap 
sampling method was designed to capture typical planktonic species, 
and therefore the common littoral taxa associated with the benthos or 
littoral zone were not sampled. The results indicated that significantly 
greater densities of copepods and rotifers were captured at Station 6B, 
the pelagic location, than at 6C, the near-shore sampling station (Fig. 
5). These differences were a result of greater densities of the copepods 
Eurytemora affinis and Diaptomus dorsalis and the rotifers Brachionus 
havanaensis, B. plicatilis, Keratella americana, K. cochlearis, and K. 
valga in midwater as opposed to near shore. 
The interesting ecological situation of Sutton Reservoir is illustrated 
by its zooplankton taxonomic composition. The taxonomic composition 
of the zooplankton is probably a result of the estuarine influence from 
the makeup water and the reservoir’s coastal geographical location. The 
two principal copepods, D. dorsalis and E. affinis , have not been 
