DOE/ORO/2327 Oak Ridge Reservation Annual Site Environmental ...

Oak Ridge Reservation
Fig. 4.31. Total taxonomic richness (mean number of taxa/sample) and total
taxonomic richness of the Ephemeroptera, Plecoptera, and Trichoptera (EPT) (mean
number of EPT taxa/sample) of the benthic macroinvertebrate communities sampled in
spring from East Fork Poplar Creek and references sites on nearby Brushy Fork
(BFK 7.6) and Hinds Creek (HCK 20.6).
in total taxa richness and EPT taxa richness at EFK 13.8 and the BFK 7.6 reference site. Although
empirical evidence is not available, the trends at these sites may be related to weather changes,
specifically precipitation. Heavy rains in spring 2009 may have affected these sites, although it is not
clear why the HCK 20.6 site was not similarly affected unless precipitation patterns in that watershed
were different. The upstream sites in EFPC, on the other hand, are dominated by species that are tolerant
of a wide range of both natural and human-caused disturbances. While the benthic macroinvertebrate
community at EFK 24.4 appears to have stabilized in recent years, there appears to have been a small
increase in both total taxa richness and EPT taxa richness at EFK 23.4.
4.5.9.3 Fish Community Monitoring
Fish communities were monitored in the spring and fall of 2009 at five sites along East Fork Poplar
Creek and at a reference stream. Over the past two decades, overall species richness, density, and the
number of pollution-sensitive fish species (Fig. 4.32) have increased at all sampling locations below Lake
4-58 The Y-12 National Security Complex