The Center for Reservoir Research (CRR) at Murray State University is nearing its 20th year. A series of papers on CRR research and education were presented at the 2006 meeting of the Ohio River Basin Consortium for Research and Education, and a selection of these is included in this issue of the Journal of the Kentucky Academy of Science. A major component of CRR is the Long-term Monitoring Program on Kentucky Lake and the resulting database. The database contains suites of physicochemical and biological data that have been collected primarily on 16 or 32 day cycles since 1988. These data are available to students and scientists through the CRR website.

Understanding groundwater flow in tributary watersheds is important for evaluating water and solute storage and inputs into reservoirs. We delineated groundwater flow at various spatial and temporal scales within the watershed of Ledbetter Creek, a third-order tributary of the Tennessee River (impounded to create Kentucky Lake) in western Kentucky. We monitored hydraulic heads in wells (primarily in the upper watershed) and piezometers (in the lower watershed) and measured the flow of a spring along the embayment where the creek enters the reservoir. Manual measurements were made at least quarterly from July 1999 to March 2002 and were made annually each April from 2002 through 2006. From May 2000 to March 2002, hydraulic heads were recorded continuously in selected piezometers. At the watershed scale, groundwater flow followed the topography, with discharge occurring along the creek and in the embayment. Hydraulic heads in piezometers responded to large storms over periods of hours to days. Longer-term fluctuations in hydraulic head reflect reservoir management in the embayment (stage increased in early spring and decreased in late summer) and seasonal variability elsewhere in the watershed.

We estimated the uptake lengths (S_w) of NO₃-N and PO₄-P using the nutrient enrichment method to assess their transport dynamics in Panther Creek (forested stream) and Ledbetter Creek (agricultural stream). The agricultural stream had higher ambient NO₃-N than the forested stream, while PO₄-P was higher in the forested stream than agricultural stream. Although we expected shorter S_w estimates in the forested stream based on the ambient nutrient concentrations and higher metabolism, the agricultural stream (Ledbetter) had shorter S_w (372 m for N and 327 and 242 m for P) than estimates from Panther Creek (753 and 870 m for N; 827 m for P). Nutrient uptake patterns in these streams may reflect the combined effects of biological activities and hydrologic characteristics. Ledbetter Creek contained several large pools and backwater areas that allowed longer residence and contact time for amended nutrients than Panther Creek. It was also assumed that Ledbetter had a potential for higher abiotic phosphorus adsorption and microbial denitrification due to the presence of large pools and finer substrate composition along the study reach.

The Little River is a highly disturbed system, heavily impacted by non-point source pollution from agricultural runoff in the form of excessive siltation, nitrogen and phosphorus, and organic pollution. Sixty-seven taxa of non-diatom benthic algae were documented for 16 sites in the Little River basin of western Kentucky during four sampling periods in 2000 and 2003. Algal taxa most often encountered included members of the Cyanophyta: Oscillatoria lutea (15 of 16 sites), O. subbrevis (13 of 16 sites), and Schizothrix calcicola (15 of 16 sites). Chlorophyta taxa most often encountered included Oedogonium sp. and Rhizoclonium hieroglyphicum, both at 10 of 16 sites. No trends were found between the algal taxa and areas of nutrient enrichment in the Little River basin. Because little is known of the benthic algal flora in the Little River, this report represents information complementary to that published previously on the benthic diatom taxa found at the same sites during the same study period.

One-year-old pine needles collected from residential and industrial locations in Kentucky were analyzed for polychlorinated biphenyls. For comparison, pine needle samples from the highly contaminated Linden Chemicals and Plastics (LCP) Superfund site in Brunswick, Georgia, also were analyzed. PCB concentrations in residential Kentucky ranged from 1.91 ng/g dry wt. to 12 ng/g dry wt. These sites were comparatively less polluted than those from the Superfund site, that had concentrations ranging from 15 ng/g dry wt. to 34 ng/g dry wt. Finger printing of PCB contamination sources was possible using pine needle PCB profiles. PCB-28 and PCB-52, PCB-101, PCB-153 and PCB-138 in pine needles indicated uptake of Aroclors −1016 and −1242, −1254, −1260 in Kentucky sites. Pine needles from the Superfund site and its vicinity contained higher chlorinated PCBs especially, PCB-196, PCB-199, and PCB-206 characteristic of Aroclor 1268. When the toxic equivalencies (TEQs) of PCBs were compared, Kentucky pine needles were only slightly lower (0.03–0.17 pg/g dry wt) than pine needles from the Superfund site (0.24–0.48 pg/g dry wt). Considering the homologue distribution of PCBs in pine needles from Kentucky and the Superfund site, lower chlorinated PCBs seem to have traveled farther than the higher chlorinated PCBs.

The macrobenthos of Ledbetter Embayment, Kentucky Lake, were sampled monthly (January 2005 through July 2006) to determine community structure with focus on the physical and chemical factors influencing spatial distribution and density. We collected 38 species, including 27 insects, four mollusks, two crustaceans, and three annelids. Species composition was similar to that observed in other midwestern reservoirs except that some taxa, typically rare in other systems, were very abundant. Mean density was 1158 m⁻² and density increased with water depth. Macroinvertebrate distribution was patchy. Profundal collector-gatherers were associated with depositional zones created by flow patterns within the embayment driven by the main stem current. Most littoral species showed associations with allochthonous input or substrate heterogeneity provided by incoming streams. The physical structure of Kentucky Lake embayments and commensurate patterns of organic matter deposition, depth, and substrate composition appear to be the primary factors structuring the macrobenthos.

The distributions and abundance of free-living copepods in Kentucky Lake were examined for the years 2000, 2002, and 2004. Vertical tow samples were collected from 16 sites every 16 days for April through November and every 32 days for December through March as part of a long-term physicochemical and biological monitoring program. Copepods comprised 14.39% of the zooplankton in tow net samples, but only 6 species were abundant. Ectocyclops phaleratus, Cryptocyclops bicolor, Mesocyclops tenuis, Eurytemora affinis, Leptodiaptomus siciloides, and Acanthocyclops vernalis accounted for 86.44% of adult copepods. With the exception of E. affinis that was found throughout the year, observed seasonal density maxima occurred at differing points during the year for each of the other major species. Most species were present during spring and summer and absent or found in low numbers throughout the remainder of the year. A. vernalis, M. tenuis, and C. bicolor exhibited density decreases that corresponded with day 160. Day 160 also marked rapid declines of other common zooplankton such as Bosmina sp., Daphnia retrocurva, and Diaphanosoma sp. Similarities in annual distribution patterns among all zooplankton suggest that common factors are exerting influence on abundances and seasonal distributions.

The unionid mussel fauna of Kentucky Lake has changed significantly over the past century. Prior to the completion of Kentucky Dam in 1944, 42 species had been reported from the mainstem Tennessee River now inundated by Kentucky Lake. After Kentucky Dam was completed, the tailwater fauna experienced minor change in species richness with 38 species being reported between 1978 and 1985. Currently, the Kentucky portion of Kentucky Lake supports 21 species. Four of these were not reported in the historical fauna prior to impoundment: Anodonta suborbiculata, Plectomerus dombeyanus, Potamilus ohiensis, and Toxolasma parvus; thus only 17 of the original species survived impoundment while four species invaded after Kentucky Dam was constructed. Amblema plicata is now the most abundant species. Plectomerus dombeyanus, first found in the Tennessee River in 1981, is the second most abundant mussel in the Kentucky portion of Kentucky Lake. Quadrula quadrula peaked in relative abundance at 51% in 1989 but subsequently declined to 10% by 2001. Few mussels survive in the deep channel where fine sediment continues to accumulate and anaerobic conditions sometimes occur. The faunal decline is typical following large dam construction, while the continuing change in the mussel fauna may reflect an aging reservoir and invasion of opportunistic species.

Sediment samples were taken from the mudflat of Ledbetter embayment at the mouth of the stream, at summer pool when it was submerged and at winter pool when it was exposed. DNA was extracted and molecular techniques were applied to avoid problems associated with bacterial culture. Amplified Ribosomal DNA Restriction Analysis (ARDRA) found 96 different fingerprints in 350 clones containing amplified sediment 16S rDNA. There were 54 different patterns in the 180 clones examined from summer samples and 55 in the 170 clones examined from winter samples. Only 13 ARDRA patterns were found in both winter and summer. These were among the most abundant organisms found and were found frequently in both summer and winter. Sequence analysis of clones with different ARDRA patterns showed that the α and β Proteobacteria were the most abundant bacteria in these samples and were abundant in both winter and summer. The α Proteobacteria, however, were the most abundant group in winter and the β Proteobacteria were the most abundant group in the summer. Data suggest that there was seasonal turnover in the bacterial community and that the organisms that can thrive under, or at least tolerate, the differences in water level, temperature, nutrient, and oxygen availability are the most abundant species in the community throughout the year.

Polygonum cuspidatum Sieb. & Zucc. is an invasive species that has spread across Britain, Europe, Canada, and the United States. Prior to this research, no analysis of genetic diversity within, or among, populations had been conducted in the United States, although population genetic diversity had been examined in Britain. An analysis of genetic diversity was carried out using Polymerase Chain Reaction (PCR)-based DNA fingerprinting on plant populations along two creeks in Rowan County, Kentucky. One creek was sampled at one-meter intervals and the other at intervals of one to nine km. The results of this analysis indicate that the plants along both of these creeks are genetically dissimilar and not clonal. The data did not support the hypothesis that P. cuspidatum is reproducing and dispersing by asexual means.

Apex Natural Arch located in northeastern Christian County, Kentucky, is the result of surface water infiltration along parallel joints, basal erosion along a weaker section of the outcrop extending to existing joints, removal of basal support, and collapse of sandstone slabs. The arch is formally named here for the village of Apex, Kentucky.