The purpose of this investigation was to characterize the population dynamics of the benthos of selected pristine thermal springs.

Actinomycetes are able to utilize a great variety of carbohydrates, like sugar. The particular kind of sugar and its concentration has decisive effect on the growth of microorganisms. The proper nutritional media aids also in the production of spores. Based on this generalization, that the growth and sporulation of microorganisms are greatly influenced by the nature and the concentration of carbohydrates, an attempt has been made to study Actinoplanes philippinensis with respect to this influence.

It seemed desirable to investigate more fully the effect of hexadecanol on the microbial population of a reservoir. It was the purpose of this investigation to determine the effect of hexadecanol on the micro-biota of Lake Hefner, to ascertain which organisms were stimulated by hexadecanol both in the laboratory and the reservoir, and to investigate the degradation of hexadecanol by microorganisms selected from Lake Hefner.

This study had a three-fold purpose. First, it was decided to determine if algae and protozoa were emitted to the air at the Denton sewage treatment plant. The information obtained could be of future importance in the fields of algal and protozoan ecology and public health. Second, it was decided to make a survey of the airborne bacteria at this plant. Some researchers have described bacterial air contamination at similar sewage treatment plants, but the one in Denton has not been studied. Third, it was hoped that in this research some relationships could be found between the bacteria and the algae and protozoa in the air in the vicinity of the sewage aeration basin. It was hypothesized that pathogenic bacteria were carried in the air with these other organisms.

The purpose of this study was to demonstrate the variability of oxygen and carbon dioxide rate of change methods for measuring primary productivity and respiration in an aquatic environment.

The purpose of this paper is to detail the distribution and quantity of soluble phosphates in an activated sludge plant, its discharge creek, and receiving reservoir. The resultant analyses and comparison of data should provide some better understanding of the fate of phosphorus in a Southwestern waterway system.

The purpose of this study is to determine if a strain of Azotobacter chroococcum isolated from the soil in northern Louisiana produces cysts which are as resistant to deleterious agents as those produced by previously reported strains os Azotobacter.

It was the purpose of this investigation to attempt to quantitate the microflora of the fields which receive the effluent from the Campbell Soup Plant, Paris, Texas, and to determine whether or not there is a correlation between the numbers and types of organisms present and the efficiency of purification of the system.

Laboratory and field investigations during the past ten years have demonstrated that certain microorganisms can cause deleterious effects in jet fuel tank systems. These investigations have brought about new concepts concerning the mechanisms of utilization of certain constituents in jet fuel tanks by microorganisms. Since the presence of microorganisms is inevitable in fuel systems, research efforts have been directed towards identification and determination of the types of microorganisms which can utilize jet fuel hydrocarbons, fuel additives, polyurethane foam structural materials, and particular hydrocarbons present in the fuel.

In this study, branchiobdellids were collected from crayfish captured from two adjacent sites in Denton County, Texas. Identification of the branchiobdellid, Cambarincola vitrea Ellis, was first made and then work was extended to include several topics of ecological interest.

The coexistence of Dipodomys ordii and Perognathus hispidus with Peromyscus maniculatus and Reithrodontomys montanus was studied in a grassland association of central Texas. The food habits of these species were compared with information from habitat vegetation analysis in an effort to determine food selectivity and the amount and importance of niche overlap and competition among these rodents.

The central objective of the study was to fractionate sedimenting organic materials according to their source (allochthonous or autochthonous) and ultimately to determine the degree of biodegradability of contributions from either source with particular reference to activities at the mud-water interface.

A large, multi-basin, reservoir (Garza-Little Elm Reservoir) in north central Texas was studied to determine the relative effects of various parameters on primary productivity. The basins were impounded several years apart,thus allowing the influence of age on water chemistry and biota to be considered. Another principal influence on water quality was secondary sewage effluent that entered one basin from a nearby source.

Three north central Texas reservoirs (Grapevine Reservoir, Lake Ray Hubbard, Lewisville Reservoir) were investigated in order to characterize the nutritional ecology, phytoplankton community structure, and primary productivity within the trophogenic zones of each. Emphasis was placed on elucidating the relative influences of the major nutrients (C, N, P, Fe, Si) and various other physico-chemical parameters on phytoplankton community biomass, structure, and productivity. Extensive physical, chemical, and biological analyses consisting of approximately eighty parameter measurements were made on each of twenty-three integrated water samples (surface to three meters) taken from the three reservoirs during the period July, 1971 to June, 1972. New methods which were employed included a high-intensity ultraviolet photocombustion procedure for the determination of total nitrogen, phosphorus, and iron, and an in vitro oxygen method for estimating community metabolism. General chemical and physical regimes are described for the three reservoirs, and various interrelationships discussed. Phytoplankton communities are delineated on bases of species composition, volume, diversity, pigments, and metabolism data. The more salient biotic and physico-chemical interrelationships are examined within the context of the limiting nutrient controversy.

The purpose of this study was to extend our understanding of the ecological relationships of P. aeruginosa by investigating the differences or similarities between the strains of this organism found in sewage and those found as pathogens in human infections. This research was approached by comparing the serological types of P. aeruginosa isolated from sewage contaminated waters in Argentina (South America) to those isolated from sewage contaminated waters in Texas. They were typed with sera obtained using P. aeruginosa isolated from human infections. The data obtained revealed that bacteria isolated from sewage in Texas and from soil and water in Argentina are antigenically similar to those isolated from human infections.

An illustrated key to the adults and known nymphs of Texas Plecoptera is provided. Species accounts, including geographic distribution within Texas, and biological notes are given. Of the twenty-seven species of Plecoptera known from Texas, six are new state records. TWo species new to science, Isoperla jewetti and Isoperla coushatta are described. Taeniopteryx starki Stewart and Szczytko, Zealeuctra arnoldi Ricker and Ross, and Zealeuctra hitei Ricker and Ross are endemic to the Edwards Plateau area of Texas. Two species, Mesocapnia frisoni (Baumam and Gaufin) and Isoperla jewetti New Species are western in origin. The remaining nineteen species (excluding Anacroneuria) are typically eastern species.

Nymphs of the 9 Nearctic Taeniopteryx species were reared and studied, 1976-78. Two morphologically allied groupings, the Taeniopteryx burksi-maura, and T. litalonicera- starki complexes corresponded with adult complexes. A key separating 7 species, based primarily upon pigment patterns and abdominal setal arrangements, was constructed. Taeniopteryx lita and T. starki were indistinguishable; T. burksi was separated from T. maurawhen no developing femoral spur was present. This study was based upon 839 nymphs. Mouthparts were not species-diagnostic. Detailed habitus illustrations were made for 6 species. Egg SEM study revealed that 3 species were 1.2-1.4 mm diameter, with a highly sculptured chorion, generally resembling a Maclura fruit; micropyle were scattered. Taeniopteryx lita, lonicera, starki and ugola nymphs were described for the first time.

Annual energy budgets of dominant benthic macro-invertebrates were examined during November 1973 to October 1974 from the benthos of a small pond ecosystem in north-central Texas. Estimates of annual secondary production (Hynes and Coleman 1968) were Procladius s. (Diptera, Chironimidae), 2.4 g m^-2 y^-1 (13 kcal m^-2 y^-1 ); Tendipes decorus (Diptera, Chironomidae), 6.0 g m^-2 y^-1 (40 kcal m^-2 y^-1 ); Brachycercus sp. (Ephemeroptera, Caenidae), 1.9 g m^-2 y^-1 (11 kcal m^-2 y^-1). Energy metabolism was measured in the laboratory at six seasonally encountered temperatures (5, 10, 15, 20, 25, and 30 C) on an acclimatization basis, and then extrapolated to the field. Estimates of annual energy metabolism are Procladius sp., 5.0 kcal m^-2 y^-1 ; Tendipes decorus, 17.2 kcal m^-2 y^-1 ; Brachycercus sp. 40.0 kcal m^-2 y^-1.

Genetic variation was examined at 19 loci encoding enzymatic and general proteins Notropis lutrensis from the Brazos River in Texas. The thermal regime of the Brazos River below Possum Kingdom Reservoir is altered due to the release of water from the hypolimnion. Summer water temperatures fluctuate as much as 7^oC. Levels of heterozygosity at the malate dehydrogenase-2 locus were correlated with the degree of water temperature fluctuation at each locality. The isozymes from three homozygous patterns of supernatant malate dehydrogenase (Mdh-l, Mdh-2) exhibited different activities at different experimental temperatures.

Four species of net-spinning caddisflies, Hydropsyche simulans Ross, Cheumatopsyche lasia Ross, Cheumatopsyche campyla Ross and Chimarra obscura (Walker) are common in the regulated portions of the Brazos River. Hydropsyche simulans spun capture nets with the largest meshdimensions; the two Cheumatopsyche species' nets had the next largest meshes, and Chimarra obscura spun nets with the smallest dimensions. Cheumatopsyche lasia and C. campyla constructed nets with similar sized meshes. The number of individuals m~2 and standing crop biomass were not significantly different among low, medium, and high velocities. Early hydropsychid instars fed on detritus while later instar H. simulans and C. campyla had larger proportions of animal material. Guts of later instar C. lasia individuals had a greater percentage of algae and diatoms.

Qualitative and microcosm models were used to predict effects of herbicide application for control of Myriophyllum spicatum. Predictions were compared to data from Pat Mayse Lake, a Texas reservoir, where localized areas were treated with endothall. Although milf oil was temporarily eliminated, when endothall was used according to manufacturer's directions, no ecologically significant direct or indirect effects were observed on nontarget species or abiotic water quality. Comparisons of the predictions with field data confirmed the capabilities of this approach for estimating risk and emphasizing the importance of identifying regulating or driving factors that modify environmental impacts of aquatic weed control programs so they can be incorporated into future risk assessments.

Stonefly life histories were studied March, 1987 through May, 1990 in the Rio Conejos, Colorado. Adult presence phenology and intensity were monitored daily in the summers of 1988 and 1989 and were coupled with monthly benthic samples to assess nymphal growth. Eggs of several species were reared. Thirty-one species were collected, with several multi-species assemblages occurring in Capnia, Utacapnia, Taenionema, Suwallia, Triznaka, Isogenoides and Isoperla. Sufficient data were obtained to reveal partial or complete life histories of 13 species, five of which have not been previously reported. New information included the 9- to 10-mo egg diapause and semivoltine life histories of Isogenoides zionensis Hanson, Pteronarcella badia (Hagen) and Pteronarcys californica Newport. Additionally, Isoperla phalerata (Smith) had univoltine-slow growth, and L quinquepunctata (Banks) was univoltine-fast. Previously unstudied emergence periods are presented for Triznaka signata (Banks), Suwallia wardi Kondratieff and Kirchner and S. pallidula (Banks). The later two species temporally segregated emergence in both years. Isoperla fulva Claassen emerged in June, and was temporally segregated from its congeners. Regression analysis of cumulative percentage catch revealed two adult presence patterns. Eight species had slopes <7%/d (extended pattern), and only two, I. zionensis and P. cal'fornica, had slopes >7 %/d (synchronous pattern). Several stoneflies …

Allozyme frequencies and general protein patterns were surveyed among selected Texas marine fishes and shellfishes to illustrate the application of biochemical genetic techniques to stock and species identification in fisheries management.

Eighty-three species of vascular plants were inventoried on the prairie relict during peak dickcissel nesting. Based on foliar cover and occurrence frequency, the five dominant plants were heath aster (Aster ericoides), eastern gammagrass (Tripsacum dactyloides), little bluestem (Schizachyrium scoparium), sensitive briar (Schrankia roemeriana) and meadow dropseed (Sporobolus asper). Sixty-one percent of dickcissel nests were constructed on or immediately next to three plant species: eastern gammagrass, sensitive briar and green milkweed.