The Trinity River flows through the Dallas-Ft. Worth Metroplex in north central Texas where it receives effluents from numerous point sources including seven large regional wastewater treatment facilities. Historically, the Trinity River has been impacted by massive wastewater loadings which often constitute > 80% of the total river discharge during low flow periods. Normally, high mass loadings correspond to the summer months, compounding the effects of a naturally stressful period, characterized by high temperatures and low dissolved oxygen concentrations. Samples from 12 stations were collected quarterly over an 18 month period from the Trinity River and two tributaries. Water samples were analyzed for a variety of water quality variables, including metals, priority pollutants, pesticides, and general water quality parameters. Water samples were also tested for acute and subchronic effects with several test species. Fish were collected at each station and assemblages were characterized using traditional classification techniques and the Index of Biotic Integrity. In addition, sediment samples were assessed for toxic effects which could have adversely impacted fish recruitment and in situ biomonitoring experiments were performed. Quantitative habitat characterization analyses were performed to gain additional information that could possibly explains differences in fish assemblage structure related to habitat variability. Data …

A comparative study was made of environmental variables and the density, biomass, diversity, and species composition of macroinvertebrates in areas downstream from a dam with a hypolimnetic release (Hungry Horse Dam on the Flathead River) and a dam with a selective withdrawal system (Libby Dam on the Kootenai River). A major objective of this study was to examine the response of macroinvertebrate communities to defined environmental gradients in temperature, flow, substrate, and food-related variables (periphyton, particulate organic carbon in the seston). In addition, the effects of experimental manipulations in discharge on macroinvertebrate drift and stranding were assessed, and the effects of temperature on the growth rates and emergence of five species of insects were measured.

Excessive nutrient loading of natural and artificial lakes has led, in some systems, to plethoric algal and aquatic macrophyte growth which can result in aesthetic degradation and undesirable tastes and odors. It would be advantageous to have some indication of the potential trophic status of a reservoir before it is filled. An objective of this study was to assess the water quality and nutrient loading potential of the tributaries entering Ray Roberts Lake, a large reservoir located in north central Texas. Samples from a maximum of thirteen sites were collected on the Elm Fork, Trinity River, Isle duBois Creek, and five additional tributaries. Data were also collected during six storms, from atmospheric deposition collectors, and from soil-water microcosms. The relationship between watershed landuse and mean water nutrient concentrations was evaluated. Significant differences will exist between the two major arms of Ray Roberts Lake: Elm Fork, Trinity River and Isle duBois Creek. While the majority of the annual phosphorus and nitrogen load entering both tributaries is coming from overland flow, the proportion is higher in Isle duBois Creek. Point sources in the Elm Fork contribute a larger percentage of the bioavailable phosphorus, which is significantly greater than in Isle duBois Creek. …

The coefficient of body temperature change (K) ranged from -0.53 to -0.072 for bass weighing 73-1440 g. The double log regression of K on weight was similar to that reported for other poikilotherms (slope = -0.57; R = 0.93). Fingerling bass were eurythermal, being capable of surviving instantaneous temperature changes over a 20 C range at acclimation temperatures of 15, 25 and 30 C and over a 15 C range at acclimation temperatures of 20 and 35 C. Preferred temperatures for adult bass measured in the laboratory ranged from 27-32 C with no relationship to day or night. The overall mean preferred temperature was 29 C. The laboratory determined preferred temperatures were supported by limited field determined body temperatures taken in a vertical temperature gradient near the discharge of a power plant effluent. Routine metabolic rates of bass from a heated reservoir and a nearby hatchery were similar from 10-30 C in summer and winter. The weight exponent (0.77) and Q^gS (1*6-2.9) were similar to those published for more northern bass populations; however, the Texas bass had lower metabolic rates than those published for the northern populations. Bass exposed to rapid temperature increase (0.2 C/min) from 25-30 C increased their …

A total of 192 largemouth bass were caught at Lake Ray Roberts, Texas (1995) to investigate five controversial bass angling techniques relative to hooking mortality. The bait types were Texas-rigged scented and non-scented plastic worms, Carolina-rigged scented and non-scented plastic worms, and live golden shiners. Overall hooking mortality was 21.87% and mortality was dependent upon bait type. Highest mortality resulted from the Texas-rigged scented lures, while the lowest mortality was generated by live golden shiners. A creel survey indicated that few anglers were having success with the investigated baits. Factors that had a confirmed effect on hooking mortality were hooking location and water temperature. Hooking mortality was not excessive compared to other similar studies.

The objective of this research was to determine if physical and microbial sediment characterizations could be used to explain benthic macroinvertebrate distribution in two branches of Lake Ray Roberts, Texas.

Wetland wastewater treatment offers low-cost, energy efficient alternatives to conventional wastewater technologies. In this study, an artificial wetland was constructed at the City of Denton, Texas Pecan Creek Water Reclamation Plant to facilitate diazinon removal from treated effluent.

The proposed biology curriculum for non-majors has one main objective, namely to improve scientific literacy among college students. The National Science Education Standards defines scientific literacy as "the knowledge and understanding of scientific concepts and processes required for personal decision making, participation in civic and cultural affairs, and economic productivity". The suggested strategies to accomplish this goal are to limit the number of topics covered, introduce relevant scientific terminology, emphasize general biological concepts and themes, and hone critical thinking and problem-solving skills. Activities such as group projects, written and oral assignments, and class discussions are effective tools to assess student ability to communicate scientifically. It is also important for students to make connections between the course subject matter and how it affects real life events.

Production dynamics in the phytoplankton community of a mesotrophic Texas reservoir were measured weekly over a four month period using 14C incubation and ATP assay methodologies. Assimilation values of 14C ranged from 0.2 to 45 ug C 1 hr1 - . Significant positive and occasionally negative changes in biomass (i.e. viable organic carbon) were observed in short term (4 hr) in situ incubations juxtapo-sitioned with the 14C experiments; viable organic carbon production, estimated with the ATP assay, ranged from -25 to +50 ug C 1l1hr1. Carbon assimilation and biomass changes did not correlate in either short term (4-5 hr.) or over the study period (6 months). However, weekly biomass trends were predicted by relative positive or negative biomass changes in the short term incubations. Biomass measurements gave a more sensitive insight into production dynamics in the phytoplankton community than did carbon assimilation measurements.

Etheostoma spectabile, E. punctulatum, and Cottus carolinae were sampled Mar., 1983, - Feb., 1984, in Flint Creek, Oklahoma. Immature E. spectabile ate primarily microcrustaceans, while mature fishes relied more on mayflies and amphipods. Juvenile E. punctulatum fed upon mayflies, amphipods, and Asellus. Mature E. punctulatum ate primarily mayflies, and other relatively larger prey. Cottus carolinae consumed chironomids almost exclusively in Jan. - Feb., 1984, while mayflies were predominant the remainder of the year. No significant habitat partitioning between the two darters, and seasonal habitat segregation between C. carolinae and the two darters was found. Dietary overlap between the darters was significantly correlated (p<0.0005) to differences in x prey sizes.

The feeding ecologies of leaf pack-associated systellognathan stoneflies were examined from 6 June 1980 21 May 1981. Species composition, seasonal abundance, nymphal growth, feeding habits and mouthpart morphology were determined for the eight dominant stonefly species. Prey preferences and predator-prey size relationships were also examined for omnivorous and carnivorous species. Foregut analysis from 2860 individuals indicated opportunistic feeding on the most abundant prey insects, usually in proportion to prey frequency. Feeding preference studies generally indicated random feeding on major prey groups. Prey and predator sizes were usually highly correlated (p<0.01), with predators expanding their prey size thresholds with growth. The potential for competition between sympatric stoneflies for prey is discussed.

Adult stonefly emergence, nymphal growth, drift and microdistribution were examined in Battle Branch, a secondorder, spring-fed stream, from November, 1982 to May, 1984. Adults of 22 species emerged successionally, with specific adults present every month. Searching emergent objects and the stream margin was best for collection of winter and early spring emerging species. Sweeping the streamside and light trapping were most efficient for late spring and summer emerging species. Nymphal growth for nine abundant species generally fit double log or semilog models. Drift was low, but did show a post-sunset pulse. Generally, leaf material was found to be significantly related (p<O.001) to density, diversity and biomass of stoneflies in Battle Branch.

Simultaneous size fractionation of plankton populations associated with NaH^14CO_3 and ^3H-glucose uptake was employed in eutrophic Lake Texoma (Texas and Oklahoma) and oligotrophic Flathead Lake (Montana). Autoradiography was utilized to determine the role of specific microorganisms in community metabolism. Ultraplankton (0.45-10 μm) dominated plankton numbers and metabolic activity in both aquatic systems. Many of the most abundant species were not the most productive, in terms of inorganic C fixation. Rates of heterotrophic uptake of ^3H-glucose were small in comparison to photolithotrophic uptake in both lakes, Photoheterotrophy was more extensive in Flathead Lake, Autoradiographs indicated that bacteria were responsible for observed photoheterotrophy. Oscillatoria sp. exhibited. mixotrophy in Lake Texoma,

Responses of periphyton and phytoplankton productivity in the lower Sulphur River (Texas-Arkansas) to bleach-kraft mill effluent (BKME) were monitored using in situ ¹⁴C incubation. Carbon assimilation rates measured downstream of mill discharge were substantially reduced from upstream levels. Periphyton and phytoplankton chlorophyll a concentrations remained relatively unchanged by the presence of BKME. Periphyton ash-free dry weight increased near the mill outfall, but decreased further downstream. Calculated productivity efficiencies (productivity:biomass) varied with variations in ¹⁴C rates. A laboratory bioassay was designed to determine the effect of BKME light-attenuation on photosynthetic rates of upstream Sulphur River periphyton and Selenastrum capricornutum Prinz. Pooled results of bioassay runs indicated a 20 per cent BKME concentration effectively reduced control ¹⁴C-assimilation levels by 50 per cent. The downstream reduction observed for in situ productivity was 5 per cent lower than that predicted by the color bioassay.

Evidence is presented to support the conclusions that (1) North Lake reservoir is less productive, contains lower standing crops of phytoplankton and total organic carbon than other local reservoirs; (2) that neither the phytoplankton nor their instantaneously-determined primary productivity was detrimentally affected by the power plant entrainment and (3) that the effect of the power plant is to cause nutrient limitation of the phytoplankton primary productivity by long-term, subtle, thermally-linked nutrient precipitation activities.

Quantification of stream macrobenthos populations has remained a perplexing problem in rivbrine ecology, despite numerous attempts at improvement. This is in part due to well documented variations in chemical and physical parameters locally and geographically, and resultant adapted macrobenthos populations. Southwood (1968) and Hynes (1970a) have reviewed the various sampling techniques developed'for the census of lotic macrobenthos populations. Needham and Usinger (1956), Chutter (1969), and others have pointed out the difficulty in obtaining adequate numbers of samples which will yield population estimates with desired statistical confidence, and still maintain some degree of sampling economy. Needham and Usinger (1956) and Gaufin et al. (1956) mentioned the "patchy" distribution of aquatic insect populations as the primary source of this difficulty. The concept of patchy distribution in insect populations was originally discussed by Andrewartha (1961). Attempts to improve confidence through improved sampling devices and techniques have led to development of numerous types of samplers. Cummins (1962) indicated that there were almost as many samplers as there were researchers.

Rates of primary production and community metabolism were monitored over a one year period using the diurnal oxygen method. Certain physico-chemical parameters were also measured, and autotrophic standing crops were estimated. An in-depth study was made of the phytoplankton community and various diversity indicies were calculated. Simple correlations were run between all parameters measured (biotic and abiotic), and their inter-relationships examined. Multiple linear regression analyses were used to develop equations predictive of production and community metabolism. Bluegreen algae were the dominant phytoplankters with blooms occurring in late summer and fall. Yearly mean production was approximately 21 kcal per meter square per day with a mean photosynthetic efficiency of 1.2 per cent. Of the various parameters measured turbidity and water temperature were most important in determining rates of primary production.

Stability of the macrobenthic community in a regulated section of the Brazos River, Texas, was evaluated. Physicochemical data and information on spatial distribution of macrobenthos were collected. Populations of two invertebrate species, Isonychia sicca and Neoperla clymene, had been greatly reduced since 1970-71 and I. sicca had been practically eliminated from this section of the Brazos. Three other insect populations, Choroterpes mexicanus, Cheumatopsche campyla and Cheumatopsyche lasia, had more than doubled their numbers since the 1970-71 study. A physicochemical gradient existed in this regulated section of the Brazos but it appeared to have changed little in comparison of earlier chemical data. A gradation of the macrobenthic community was evident as distance from the dam increased,