Par Pond Research Articles

Mercury and Radiocesium Accumulation and Associations With Sublethal Endpoints in the Florida Green Watersnake (Nerodia floridana).

Mercury (Hg) and radiocesium (137 Cs) are well-known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We investigated the bioaccumulation of Hg and 137 Cs and associations with sublethal effects (standard metabolic rate [SMR] and hemoparasite infections) in Florida green watersnakes (Nerodia floridana). We captured 78 snakes from three former nuclear cooling reservoirs on the US Department of Energy's Savannah River Site in South Carolina (USA). For captured snakes, we (1) determined whole-body 137 Cs, (2) quantified total Hg (THg) using snake tail clips, (3) conducted hemoparasite counts, and (4) measured the SMR. We used multiple regression models to determine associations among snake body size, capture location, sex, tail THg, whole-body 137 Cs, Hepatozoon spp. prevalence and parasitemia, and SMR. Average whole-body 137 Cs (0.23 ± 0.08 Becquerels [Bq]/g; range: 0.00-1.02 Bq/g) was correlated with snake body size and differed significantly by capture site (Pond B: 0.67 ± 0.05 Bq/g; Par Pond: 0.10 ± 0.02 Bq/g; Pond 2: 0.03 ± 0.02 Bq/g). Tail THg (0.33 ± 0.03 mg/kg dry wt; range: 0.16-2.10 mg/kg) was significantly correlated with snake body size but did not differ by capture site. We found no clear relationship between SMR and contaminant burdens. However, models indicated that the prevalence of Hepatozoon spp. in snakes was inversely related to increasing whole-body 137 Cs burdens. Our results indicate the bioaccumulation of Hg and 137 Cs in N. floridana and further demonstrate the utility of aquatic snakes as bioindicators. Our results also suggest a decrease in Hepatozoon spp. prevalence related to increased burdens of 137 Cs. Although the results are intriguing, further research is needed to understand the dynamics between 137 Cs and Hepatozoon spp. infections in semiaquatic snakes. Environ Toxicol Chem 2022;41:758-770. © 2022 SETAC.

Radiocesium in migratory aquatic game birds using contaminated U.S. Department of Energy reactor-cooling reservoirs: A long-term perspective

Low-level releases of radiocesium into former nuclear reactor cooling-reservoirs on the U.S. Department of Energy's Savannah River Site (SRS) in South Carolina, USA, dating primarily to the late 1950s and early 1960s, have allowed examination of long-term contaminant attenuation in biota occupying these habitats. Periodic collections of migratory game birds since the 1970s have documented 137Cs (radiocesium) activity concentrations in birds of SRS reservoirs, including mainly Par Pond and Pond B. In this study, during 2014 and 2015 we released wild-caught American coots (Fulica americana) and ring-necked ducks (Aythya collaris) onto Pond B. We made lethal collections of these same birds with residence times ranging from 32 to 173 days to examine radiocesium uptake and estimate the rate of natural attenuation. The two species achieved asymptotic whole-body activity concentrations of radiocesium at different times, with ring-necked ducks requiring almost three times longer than the 30–35 days needed by coots. We estimated ecological half-life (Te) for Pond B coots over a 28-yr period as 16.8 yr (95% CI = 12.9–24.2 yr). Pond B coot Te was nearly four times longer than Te for coots at nearby Par Pond where radiocesium bioavailability had been constrained for decades by pumping of potassium-enriched river water into that reservoir. Te could not be estimated from long-term data for radiocesium in Pond B diving ducks, including ring-necked ducks, likely because of high variability in residence times of ducks on Pond B. Our results highlight the importance: (1) for risk managers to understand site-specific bio-geochemistry of radiocesium for successful implementation of countermeasures at contaminated sites and (2) of residence time as a critical determinant of observed radiocesium activity concentrations in highly mobile wildlife inhabiting contaminated habitats.

Contrasting cesium dynamics in neighboring deep and shallow warm-water reservoirs

To measure the long term retention and seasonal dynamics of an initial 4 kg addition of 133Cs into an 11.4-ha, 157,000 m 3 reservoir (Pond 4, near Aiken, South Carolina, USA), the concentrations and inventories of 133Cs in the water column were measured at periodical intervals for 522 days following the 1 August, 1999 release. After rapid declines in concentrations and inventories during the first 90 days, the 133Cs concentrations in the water column declined at an average proportional rate of 0.004 d −1. However, there were periods of less rapid and more rapid rates of declines, and these were correlated with periods of increasing and decreasing K concentrations in the water column. The decline rates were less and the K concentrations greater in the winter than in the summer. In the deeper, neighboring monomictic reservoirs of Par Pond and Pond B, a yearly cycle of increasing and decreasing 137Cs concentrations in the water column is driven by anoxic remobilization of Cs from the sediments into a persistent summer hypolimnion. In Pond 4, whose mean depth of 1.6 m is too shallow to support a persistent anoxic hypolimnion, the pattern of yearly dynamics for K and Cs appear to be related to the accumulation and release of these elements from the extensive, seasonal macrophyte communities. The contrasting results between Pond 4 and Pond B suggest that a full appreciation of the relative importance of 1) anoxic remobilization and 2) accumulation and release by macrophytes in these systems remains to be established.

“Active” Passive Sampling in Two Species of Lepomis from Par Pond, South Carolina, United States: a Case Study of Infracommunity Nestedness

The influence of ontological diet shifts on infracommunity nestedness was examined by comparing the infracommunity structure of Lepomis gulosus and Lepomis macrochirus at 2 localities in Par Pond, South Carolina, United States. Fill-constrained, occurrence-constrained, and abundance-constrained null models were used to evaluate the degree of nestedness. The presence-absence matrices from all 4 component communities had significantly fewer discrepancies than those produced by the fill-constrained model, and none had significantly fewer discrepancies than those produced by the occurrence-constrained model. Only the presence-absence matrix for the infracommunities of L. gulosus from the Cold Dam locality had significantly fewer discrepancies than those produced by the abundance-constrained null model. The nestedness of the 4 samples could not be distinguished from that expected under a hypothesis of passive sampling. A positive correlation between host size and total parasite abundance indicates the passive mechanism has a deterministic basis. Thus, even in the absence of habitat or diet shifts, nestedness can arise in infracommunities of freshwater fishes when older, larger fish have sampled more individuals from an uneven distribution of infective stages.

Emigration of Fish from Two South Carolina Cooling Reservoirs

AbstractWe assessed fish escapement from two South Carolina reservoirs, Par Pond and L Lake, from spring 2002 through summer 2003. Escapement was greatest in the spring and early summer, with lake chubsucker Erimyzon sucetta dominating the escapement catch in early spring and several sunfishes Lepomis spp. dominating in late spring and early summer. Most of the escaping centrarchids were bluegill L. macrochirus, warmouth L. gulosus, and redbreast sunfish L. auritus in L Lake and warmouths, bluegills, dollar sunfish L. marginatus, and spotted sunfish L. punctatus in Par Pond. Escapement was enhanced by high reservoir water levels and surface discharge over the spillway. Escapement declined during periods of hypolimnetic release from bottom discharge gates. Location of the Par Pond discharge structure in the littoral zone rather than the pelagic zone as in L Lake contributed to greater escapement of littoral species in Par Pond. Species composition in the escapement catches and reservoirs was not significantly correlated. Relatively low escapement from L Lake and Par Pond compared with that in other reservoirs may have been related to the configuration of the discharge structures, low water levels during 2002, fish habitat preferences, species composition and abundance in the reservoirs, and low rates of discharge.

Mercury Concentrations in Largemouth BASS (Micropterus Salmoides) from Five South Carolina Reservoirs

Mercury concentrations in largemouth bass (Micropterus salmoides) bass were compared among five reservoirs in South Carolina. Three of these reservoirs (Lake Russell, Lake Thurmond, and Lake Marion) are accessible to the public and two (L-Lake and Par Pond) are located on the U.S. Department of Energy's Savannah River Site (SRS), which is closed to public access. Age-adjusted mercury concentrations were significantly higher in SRS bass compared to the offsite reservoirs. In addition, mercury concentrations were significantly higher in bass from Par Pond compared to L-Lake and in bass from Lakes Russell and Thurmond compared to Lake Marion. No mercury concentrations in excess of the U.S. Food and Drug Administration action level (1.0 mg⋅kg−1) were found in any bass from the public-accessible reservoirs. However, the majority of fish from these reservoirs had mercury concentrations that fall into or exceed the U.S. Environmental Protection Agency consumption category of “no more than one per week". In addition, most fish from these reservoirs had mercury levels in excess of those believed to be detrimental to sensitive avian species.

Inventory and spatial pattern of [formula omitted] in a pond: a comparison of two survey methods

The sediments of Pond A, a former Savannah River Site cooling pond for R-reactor, were contaminated with 137 Cs between 1954 and 1964. Pond A is unique because it is very shallow and contains an extremely high density of aquatic vegetation and old, undecomposed tree stumps which modify normal sedimentation processes and cause special radiological characterization challenges. To determine the most efficient technique for estimating inventory and spatial patterns of 137 Cs , we measured exposure rates at 124 sediment surface locations with two types of thermoluminescent dosimeters (TLDs) and compared them to estimates calculated from 137 Cs measured in 58 extracted sediment cores. The mean net exposure rate (±1SEM) measured at the sediment water interface with a UD-802 multi-element TLD (differentially shielded lithium borate and calcium sulfate) was 40±4 μR h −1, while the corresponding value measured with a CaF 2 TLD was 64±10 μR h −1. Both sets of TLD measurements were found to correlate well with each other ( R 2=0.88, p<0.001 ), and moderately well with theoretical calculations derived from 137 Cs activity concentrations measured in sediment cores ( R 2>0.50 ). The corresponding mean exposure rate calculated from the sediment data, 69±10 μR h −1, was likely an over-estimate resulting from the core sampling bias created by the large number of tree stumps. Overall, peak 137 Cs activity occurred at ∼2–4 cm depth in the sediment cores, with >99% in the top 20 cm of sediment. The total 137 Cs inventory of Pond A was estimated as 4.1±0.5×10 10 Bq, with most activity located in the deeper portions. Approximately 1% of the 137 Cs activity thought to have been released by R-Reactor can be accounted for in Pond A, with an additional 53% estimated from other work to be in the much larger Pond B, and Par Pond, located further down the drainage. However, the mean deposition in Pond A (7.9×10 9 Bq ha −1) was higher than either Pond B (4.0×10 9 Bq ha −1), or Par Pond (1.4×10 9 Bq ha −1). It was concluded that, although the TLD method was more efficient and could employ more sampling locations to estimate spatial pattern, a reasonable amount of coring was essential to determine depth distribution, radionuclide composition, and to interpret the TLD data. Optimal estimation and characterization efficiency can benefit from simultaneous application of both techniques.

Lipid and reproductive cycles of bluegills ( Lepomis macrochirus) exposed to 35 years of elevated environmental temperatures

1. We studied bluegills to compare how thermal perturbation affected lipid dynamics and reproductive cycles of fish from heated (Pond C) and normothermic (Par Pond) sites. 2. Bodies of bluegills contained over 90%, and gonads and livers 10% of the non-polar lipids. 3.Overall, the percent body lipids of bluegills from the heated pond was twice as high (12.4%) as that of Par Pond bluegills (6.6%). 4. During a prolonged reactor down period, when both ponds were normothermic, body lipids of bluegills from Pond C and Par Pond increased at a rate of approximately 3 and 1% of body mass per week, respectively. 5. Juveniles from Pond C had higher percent stored lipids than did adult males or females. 6. Lipid cycling in Par Pond bluegills was seasonal, whereas Pond C bluegill lipid cycles corresponded to long reactor down periods.

Radiocesium in Mourning Doves: Effects of a Contaminated Reservoir Drawdown and Risk to Human Consumers

From September 1991 through January 1995, partial drawdown of a 1,130-ha U.S. Department of Energy reactor cooling reservoir (Par Pond) in South Carolina exposed sediments contaminated by low-level radiocesium ( 137 Cs). These exposed sediments were designated as a U.S. Environmental Protection Agency (EPA) superfund site. Whole-body and muscle concentrations of 137 Cs in mourning doves (Zenaida macroura) collected from Par Pond in 1992 and 1993 were 2-3 orders of magnitude higher than in doves from nearby public dove-hunting fields located 12 and 32 km away. Only 1 of 102 Par Pond doves exceeded the European Economic Community limit of 0.60 Becquerels (Bq) 137 Cs/g for fresh meat. A human risk analysis based on consumption of doves at the observed maximum of muscle 137 Cs concentration (0.82 Bq/g wet mass) indicated no more than 41 doves could be consumed by an individual per year at that level before the EPA threshold for action on a superfund site would be exceeded (i.e., further site characterization, possible remedial action). Levels of whole-body 137 Cs in doves from Par Pond declined by >75% from 1992 through 1994. Pokeweed (Phytolacca americana) seeds, the dominant food of doves foraging on the exposed lake bed, likewise declined (>90%) in 137 Cs content over the period. We noted subtle annual changes in the diets of doves that likely contributed to reduced rates of 137 Cs ingestion as the drawdown progressed. Doves differed by age class in their food intake and selection, and immature doves showed higher levels of ingesta 137 Cs. However, age classes did not differ in whole-body 137 Cs (P = 0.156) or muscle 137 Cs (P = 0.181). Dove whole-body 137 cs was a good predictor (r2 = 0.94) of muscle 137 Cs, and thus provides the opportunity to estimate levels of 137 Cs in edible muscle without destructive sampling by simply subjecting live-captured birds to whole-body determination of 137 Cs content. The radiological consequences of a long-term drawdown or complete draining of such a reservoir are not clear.

Sorption of Cs and Sr to profundal sediments of a Savannah River Site reservoir

Laboratory measurements of the sorption and desorption of 134Cs and 85Sr to sediments were conducted. These sediments were sampled from the top 1 cm of the profundal zone of Par Pond at the Savannah River Site, Aiken, South Carolina. The isotopes 134Cs and 85Sr were used to trace the sorption properties of the main contaminants found in the reservoir, which are 137Cs and 90Sr, respectively. The sorption behavior of these two elements was studied using spiked sediment/water slurries of a variable, but known, mass to volume ratio. The results reveal that Sr undergoes significant reversible sorption while a fraction of Cs irreversibly sorbs to the sediment. The K d for 137Cs was a function of the slurry ratio, pH, conductivity, and contact time. These factors were inter-related since the sediments released ions to the slurry mixture which simultaneously decreased the pH and increased the conductivity. The calculated K d at equilibrium was 2.8 × 10 4 for 134Cs after 60 days and 1 × 10 3 for 85Sr after 7 days at a pH ~ 6 and a slurry ratio of 1:1000 g/ml.

Radon tracing of groundwater input into Par Pond, Savannah River Site

The groundwater contribution into Par Pond, a former cooling reservoir for two nuclear reactors located on the Department of Energy's Savannah River Site (South Carolina), was estimated using a standard hydrologic budget as well as one augmented by a natural tracer approach. We determined a geochemical budget for 222Rn, normally found at much higher concentrations in groundwater than surface waters, to assist in constraining the hydrologic estimates. The radon budget accounted for all quantifiable surface sources and sinks including the flux across the sediment-water interface which was determined by application of an advection-diffusion model. All hydrologic parameters and radon concentrations were monitored seasonally from February 1994 to August 1995. Using the water balance approach alone, the average groundwater discharge entering the lake was estimated to have an upper limit of approximately 0.95 ± 0.13 m 3 s −1. The groundwater contribution obtained using the combined hydrologic/ 222Rn approach ranged from 0.17 to 0.76 m 3 s −1 with a best estimate of 0.35 ± 0.16 m 3 s −1. Lake profiles show enhanced 222Rn concentrations in some areas indicating that groundwater enters Par Pond mostly through a small region in the northern portion of the lake, probably via small seeps or springs. Estimates show that groundwater plays a significant role in the overall water budget of the lake, accounting for 10%–33% of the total estimated inflow from all measured sources. Our results show that supplementing a standard hydrological water balance with radon budget considerations helps to constrain estimated groundwater flow into surface reservoirs.

Metal Levels in Mourning Doves from South Carolina: Potential Hazards to Doves and Hunters

Most game birds are found in lower trophic levels, but since such birds are harvested and consumed by humans, there is a particular need to assess their contaminant levels. In this paper, we report concentrations of mercury, lead, cadmium, selenium, manganese, and chromium in the breast feathers, liver, and muscle of mourning doves (Zenaida macroura) collected at a partially drawn-down, contaminated reactor-cooling reservoir (Par Pond) on the Department of Energy's Savannah River Site in South Carolina and at nearby agricultural fields managed as dove hunting areas. We test the hypothesis that the levels in doves are not harmful to either dove populations or humans. We also tested the simultaneous effects of collection location, year (1992, 1993), and dove age-class (hatch-year vs after hatch-year) on heavy metal and selenium levels. For all three tissues, mercury levels were nondetectable at all locations. Lead was highest in tissues from agricultural fields with prior histories of dove hunting activities. Doves at those fields were likely ingesting lead shot to a greater degree than at the recently drawn-down reservoir which was closed to public access and hunting. For other metals, Par Pond doves had equally high or higher tissue levels. For all metals, levels in doves from South Carolina were generally within the lower range of those reported in the literature, suggesting that these metals were likely to pose no health problems to these doves. Except for lead and selenium, metal levels in dove muscle that we observed were well below reference metal doses established for human intake. Lead and selenium, at the levels described here, would only be a problem if a child (not an adult) ate 120 g of dove meat every day of the year. Thus, we conclude that meat from these doves, if consumed by hunters, would not pose a risk.

Tissue mercury concentrations in alligators (Alligator mississippiensis) from the Florida Everglades and the Savannah River Site, South Carolina.

Mercury pollution is a serious problem in some areas of the southeastern United States. Due to biomagnification, long-lived predators should have high Hg concentrations in affected areas. American alligators(Alligator mississippiensis) are important predators in many southwestern wetlands, but little information is available on Hg concentrations in this species. We collected tissues from alligators inhabiting two sites in the Everglades, Florida (n = 18) and a manmade reservoir in South Carolina (Par Pond; n = 44), all with documented histories of Hg contamination, and analyzed them for total Hg. Mean concentrations in kidney, liver, muscle, and dermal scutes of alligators from the Everglades (expressed as mg Hg/kg dry mass +/- S.E.M.) were 36.42 +/- 5.23, 41.09 +/- 5.90, 5.57 +/- 0.47, and 5.83 +/- 1.04, respectively. Concentrations in liver, muscle, and scutes from Par Pond alligators were 17.73 +/- 2.56, 4.08 +/- 0.46, and 4.58 +/- 0.63,respectively. Blood from Par Pond alligators contained 2.20 +/- 0.38 mg Hg/kg wet mass. Mercury concentrations did not differ among sexes at any location. Tissue Hg levels did not differ significantly between Everglades locations,but were lower in Par Pond. In Everglades alligators, Hg concentrations in all tissues were positively correlated, as were tissue Hg and total length. Only total length and scute Hg were correlated in Par Pond alligators. Regression revealed a significant relationship between muscle and scute Hg concentrations in Everglades alligators, but not Par Pond alligators. Alligators living in polluted areas can accumulate substantial concentrations of Hg, but relationships among Hg concentrations in specific tissues may vary with location or age and size of the animals sampled.

Recovery of a Reservoir Fish Community from Drawdown Related Impacts

Abstract Par Pond, a 10.5-km2 reservoir in South Carolina, was drained over a period of 3 months to less than 50% of its former surface area and volume; it was maintained in that state for approximately 3.5 years. The drawdown resulted in significant reductions in fish abundance and number of fish species, changes in the relative abundance of fishes, and changes in the size structure of individual species of fish. An important factor contributing to these changes was complete loss of the original littoral zone. Within approximately 9 months of the refill of Par Pond to its former level, the fish community had recovered in terms of number of species and overall fish abundance, and had nearly recovered in terms of species composition. However, size structures after refill were different than before the drawdown: large individuals were fewer and small individuals greater in number. Factors contributing to the recovery of the Par Pond fish community included recolonization from refugia, high reproductive rate...

Genetic Differentiation between Unionicola formosa and U. foili (Acari: Unionicolidae): Cryptic Species of Molluscan Symbionts

Genetic Differentiation between Unionicola formosa and U. foili (Acari: Unionicolidae): Cryptic Species of Molluscan Symbionts

Predation-Induced Differences in Growth and Reproduction of Bluegills (Lepomis macrochirus)

two years older and 80 mm longer at maturity than bluegills in other southeastern United States reservoirs. Bluegills in Par Pond began reproduction at about the same size that they outgrew the threat of predation (about 190 mm total length). Differences in bluegill growth and reproduction appeared largely attributable to differences in abundance and size structure of predators in these reservoirs. Effects of high levels of predation on growth rates and reproduction of bluegills in this study were different from the effects of predation at low levels as studied in other systems.

Long-term recovery from 137Cs contamination in Par Pond reservoir, Savannah River plant, South Carolina, USA

Long-term recovery from ¹³⁷Cs contamination in Par Pond reservoir, Savannah River plant, South Carolina, USA

Validation of Otolith Annuli of Bluegills in a Southeastern Thermal Reservoir

Abstract Opaque bands on otoliths were validated as annuli for bluegills Lepomis macrochirus throughout their lives in Par Pond, a nuclear reactor cooling reservoir in South Carolina. Whole mounts of otoliths were suitable for age determination of young bluegills (less than 5 years old), but both whole mounts and otolith sections were necessary for age determination of older bluegills. Marginal increment analyses indicated that annulus formation began as early as February and was complete by June in bluegills of ages 1–9. Annulus formation began earlier in younger (age 1–2) bluegills than in older individuals. Similarity of observed and back-calculated sizes at age supported identification of opaque bands as annuli. Input of warm water from reactor operation occasionally produced opaque bands (false annuli) on otoliths; however, the faintness and incompleteness of such bands clearly distinguished them from true annuli. Identification of the first annulus of some otoliths was problematic due to the occurre...

Growth of Juvenile Alligators in Par Pond, Savannah River Site, South Carolina

Growth of Juvenile Alligators in Par Pond, Savannah River Site, South Carolina

Long-Term Changes in a Population of Alligator mississippiensis in South Carolina

The status of the American alligator in a man-made reservoir in South Carolina was deter- mined through the use of mark-recapture and mark-resighting techniques. Results were compared to studies conducted during the 1970s to determine changes in population size, population structure, and number of nests. Over the last 14 years the number of alligators in Par Pond has more than doubled (from an estimated 110 to 266), and the size structure of the population has shifted from one with a high proportion of large adults to one with a high proportion of juveniles (<1.8 m). The sex ratio of animals captured from 1986-1989 (2.6 male: 1 female) was similar to that found in the 1970s (3.2:1; Murphy, 1977). The number of nests and the number of successful nests was variable among years, ranging from no nests in 1986 to 8 nests in 1988 for an average of 4.0 nests per year, an increase from the 2.3 observed during the 1970s. Overall, the alligator population in Par Pond appears to be quite healthy, showing an overall average annual exponential rate of increase (r.p.a) of 6% and a juvenile r.p.a. of 10%. It is expected that the population will continue to increase in size, but that the average annual exponential rate of increase will decrease as the carrying capacity of Par Pond is reached.