Introduction: Increased temperature as a stress factor in aquatic environments has recently received much attention. Human population growth accompanied by expanded demands for electrical energy has resulted in increased construction of power generating facilities. Conventional fossil fuel power plants are being built to produce many times the electricity of those built in previous years. Nuclear power plants, not economically feasible in small sizes, are being constructed to generate even more electrical energy per unit than the new conventional units. Nuclear power facilities produce heat less efficiently and, thus, require approximately fifty percent more cooling per BTU than usual methods (Kolflat, 1968). Increased exposure of populations and communities of aquatic organisms to thermal pollution can thus be anticipated when natural water systems are utilized as a cooling source. The majority of research effort relative to the effects of heated waste waters on aquatic systems has been directed towards macro- as opposed to micro-organisms. While the use of microorganisms in general pollution monitoring is not a nevi concept; for examples see Kolkwitz and Marsson (1908); Butcher (1947); Fjerdingstad (1962), most of the existing effort has been in the area of correlation of species to various polluted situations. The major disadvantages of such approaches as well as the use of populations and communities of microorganisms in pollution monitoring are discussed in Cairns and Lanza (1971) and Cairns, etc. (submitted)... <i>Vita removed Nov. 30, 2011. GMc</i> / Ph. D.

This study investigated the short-term inhibitory effects of 8 chlorinated compounds on aquatic microorganism heterotrophic activity. A technique involving the measurement of substrate uptake rates using radio-actively labeled glucose was employed. All compounds studied have been identified as foreign pollutants in aquatic environments and include the highly toxic ones DDT, dieldrin and a PCB (Aroclor 1254). The aquatic microorganisms were predominatly bacteria. On a short-term basis, the PCB and tetrachlorophenol were the most toxic pollutants, decreasing the maximum glucose uptake rate (Vmax) by 50 percent at 250 ppb concentrations. The remaining pollutants had little effect under 2500 ppb. In addition, tetrachlorophenol was the only compound to significantly increase glucose turnover time (Tt). Results from other experiments were: the toxicity of tetrachlorophenol varied according to the (environmental) water temperature; tetrachlorophenol affected the uptake of glucose more than that of two amino acids, alanine and glutamic acid; with respect to di-, tri-, and tetrachlorophenol, neither the chlorine percentage per pollutant molecule, nor the number of pollutant molecules per mole of water, varied linearly with the pollutant's ability to inhibit glucose uptake; the combined toxicities of various pollutants reduced uptake to only 9 percent below the average of their separate effects; and none of the 4 pollutants tested for long-term effects (DDT, PCB, dieldrin and tetrachorophenol) inhibited uptake after 4 days. It was concluded that the two tests (Type I and Type II as described in Section 2) were quick and reliable techniques for assessing the short and long-term effects of a concentration of a pollutant on heterotrophic activity. It was also determined that other pollutants should be tested for their long-term effects under a variety of conditions (for example, their effects on different substrates and on the sediment microbial community). / Science, Faculty of / Zoology, Department of / Graduate

The influence of environmental contaminants on the muskrat population inhabiting the contaminated lower region of the Elizabeth River was studied through an analysis of contaminant burdens, physiological characteristics, and population dynamics in comparison to those of muskrat populations from a less contaminated region of the Elizabeth River (upper region) and a nearby uncontaminated river (Nansemond River). A total of 76 muskrats was collected for contaminant analysis during December 1986 - January 1987 and December 1987 - February 1988. Twenty-two of 35 carcasses analyzed for polynuclear aromatic hydrocarbons (PAHs) had detectable levels of from 1 to 6 PAH compounds. Only three muskrats from the lower region and one from the upper region of the Elizabeth River had PAH concentrations greater than 0.03 ppm dry wt (lower limit of detection). Liver DNA adduct levels were not significantly different between muskrats collected from the lower region of the Elizabeth River and muskrats collected from the Nansemond River. However, liver microsomal enzyme activity was greater in lower region Elizabeth River muskrats than in upper region Elizabeth River or Nansemond River muskrats, as indicated by significantly reduced pentobarbital sleeping times. The mean concentration of 14 PAH compounds detected in surface sediments from the lower region of the Elizabeth River (N = 10) was significantly greater than the mean concentration detected in surface sediments collected from the upper region of the Elizabeth River (N = 5) or Nansemond River (N = 5). Of 22 organochlorine compounds analyzed in 35 muskrat carcasses, dieldrin was detected in one carcass (0.25 ppm) from the lower region of the Elizabeth River, polychlorinated biphenyls were detected in two carcasses (0.66 ppm and 0.45 ppm) from the upper region of the Elizabeth River, and p,p′-DDE was detected in two carcasses (0.03 ppm each) from the upper region of the Elizabeth River and one carcass (0.03 ppm) from the Nansemond River. p,p′-DDE was detected in 5 of 10 sediment samples from the lower region and 2 of 5 sediment samples from the upper region of the Elizabeth River. p,p′-DDD was detected in 3 of 10 sediment samples from the lower region of the Elizabeth River. Twenty-seven of 33 metals analyzed were detected in muskrat kidneys and 9 of these were significantly different among the three study regions. Mean aluminum (13.19 ppm), cadmium (3.08 ppm), copper (12.85 ppm), nickel (0.50 ppm), and zinc (88.38 ppm) concentrations were greatest in lower region Elizabeth River muskrat kidneys. Mean cadmium (1.07 ppm), chromium (43.4 ppm), lead (104 ppm), tungsten (38.1 ppm), and mercury (0.50 ppm) concentrations were significantly greater in lower Elizabeth River sediment samples. Density estimates based on shore length for the lower and upper regions of the Elizabeth River were 0.86 muskrats/IOO m of shore and 1.1 muskrats/lOO m of shore, respectively in 1987. Seventy-five female muskrats had a total of 637 placental scars (x̅ = 8.49) ranging from 1 - 20. The number of placental scars per female did not differ significantly among regions. Twelve pregnant muskrats had a total of 54 fetuses (x̅ = 4.5, range = 3 - 6). Average number of litters per year was estimated to be 1.89 with births occurring primarily from April - May and in September. Results indicated that the environmental contaminants found in the lower region of the Elizabeth River have minimal influence on the muskrats from this region. Body and spleen weights were reduced but reproduction was not affected, and the muskrat density in this region appears to be stable and similar to the density in a less contaminated area. Immunological function may be depressed. / Ph. D.