The Trinity River passes through the Dallas-Fort Worth metroplex receiving point and non-point source contaminant loadings. Lepomis spp. were collected at twelve sampling locations in the Trinity River in August 1987 and September 1988 and analyzed for organochlorine pesticides and heavy metals. Results from the study were compared to existing U.S. FDA action and tolerance levels, LC50s, and historical data. Various longitudinal trends and some concentration patterns were observed. Continual study of pesticide and metal body burdens in fish allow testing for trends, and thereby, lead to a better understanding of the distribution of contaminants in the Trinity River.

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 were analyzed using regression, univariate, multivariate, and descriptive statistical techniques and new approaches for analyzing impact assessment data were discussed. Results indicated that the most substantial impacts on fish assemblages were confined to a segment of the river where a sequence of point sources, in close proximity to each other, were overloading the river's capacity to sufficiently dilute and/or detoxify the effluent. Data also indicated the presence of episodic toxicity from nonpoint sources. In addition, toxic effects in sediment samples and differences in habitat were detected and may have contributed to measured differences among fish assemblages in the Trinity River.

Federal regulations such as the Clean Water Act (P.L. 92-500), and its amendments, direct the Environment Protection Agency (EPA) to implement programs to control the releases of conventional pollutants and toxics into the waterways of the United States. The EPA began requiring treatment plants to conduct toxicity tests (biomonitoring) of their effluent discharges. To control toxicity caused by chlorination of wastewater discharges, the EPA also began requiring some treatment facilities to dechlorinate their wastewater before discharging. This research was funded by the EPA to document the changes that occurred in the Trinity River from the dechlorination of the effluent from Ft. Worth's Village Creek municipal wastewater treatment plant. The study occurred over a two year period beginning in August 1990. A wide variety of biological field assessments and toxicological assays were used to measure various responses. Seven river stations, covering approximately twenty river miles, and the treatment plant effluent were assessed. Two of the river stations were upstream from the treatment plant and used as reference sites. The remaining five river stations were downstream from the treatment plant, spread out over seventeen river miles. The study evaluated the impact of chlorination prior to dechlorination, which served as a baseline. Responses determined during dechlorination were compared to the baseline data. An overall improvement in species richness and diversity was seen at those river stations which had previously been adversely impacted by chlorine. Aquatic toxicity tests, such as those required to be used by dischargers, were conducted during this study. Periodic toxicity was observed with these tests in the effluent and river samples after dechlorination was initiated. Those tests, along with in situ toxicity assays, proved to be good predictors of biological community responses.

Grand Coulee Dam created Franklin D. Roosevelt Lake as part of the Columbia Basin Project. Located in northeastern Washington State, the Project provides economically important hydropower (19 billion kilowatt hours per year), irrigation (225,000 ha), flood control, and sport fishing ($5 to 20 million annually). A good system understanding aids in balancing these beneficial uses for the 230 km long reservoir. The reservoir's atypical 45-day mean residence time is much shorter than a typical lake, and much longer than for a riverine dam. The spring freshet requires drawdowns of 15 to 20 m for flood control—the driving characteristic of reservoir operations. A physically based two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 Version 3.5 (Cole and Wells, 2006), is coupled with a fish bioenergetics model based on the Stockwell and Johnson model (1997, 1999) to examine the effects of hydrodynamics on the reservoir algae-zooplankton-kokanee food web. This model was applied and calibrated to Lake Roosevelt with model improvements of multiple zooplankton compartments and zooplankton omnivory. Calibration parameters included temperature, dissolved oxygen, nutrients, algae, and zooplankton. The fish bioenergetics model is applied over the entire reservoir model space to generate a spatial and temporal fish growth potential distribution. The fish model refinements include sub-daily time-steps and an optimized vertical foraging strategy. The linked model suggests that kokanee fish growth potential is seasonally limited by both warm water and prey densities. While the lake ecology is significantly affected by the reservoir operations in general, the pelagic fish growth potential did not appear sensitive to minor changes in reservoir operations. However, the model suggests that the advantageous foraging locations shift seasonally and that optimal foraging strategies are dependent on fish size.

No description available.

Bambara groundnut (Vigna subterranea L. Verdc) is a drought tolerant African legume capable of producing reasonable yields where other crops may fail. However, it remains an underutilised crop, owing to limited research, cultivated using landraces, of which scant information is available describing their agronomy and genetic diversity. The aim of this study was to evaluate the response of bambara landraces from different geographical locations to water stress under controlled and field conditions. Seeds were sourced from subsistence farmers of Tugela Ferry and Deepdale in KwaZulu-Natal (South Africa) and Zimbabwe, and characterised into three seed coat colours: light-brown, brown and red. Seed quality was assessed using the standard germination test. Vigour indices of germination velocity index and mean germination time were determined. Seedling establishment was evaluated using seedling trays using a factorial experiment, with four factors: 1. provenance – (Tugela Ferry and Deepdale), 2. seed colour – (red, light-brown and brown), 3. water regimes – (30%, 60% and 100% field capacity), and 4. soil media – (clay, sand and clay + sand). Seedling leaf samples were used to evaluate proline accumulation as an indicator of stress tolerance. A field trial was used to evaluate productivity of bambara landraces under rainfed and irrigated conditions. A pot trial was conducted under controlled environment conditions with three factors: temperature (33/27°C and 21/15°C), water regimes (30% and 100% of crop water requirement) and bambara landrace selections. Results showed no significant differences in germination capacity between bambara landrace selections. Germination time differed significantly (P<0.001) between bambara landrace selections. The Jozini provenance was shown to perform best, followed by Zimbabwe, Tugela Ferry and Deepdale. Brown landrace selections had higher (P<0.001) germination compared with red and light-brown selections, respectively. Seedling establishment showed that emergence was higher (P<0.001) at 100% FC compared with 60% FC and 30% FC. Emergence was higher (P<0.001) in the Sand+Clay mixture compared with Clay and Sand media. Dark-coloured selections had higher (P<0.001) emergence compared with light-coloured selections. Results from the field trial showed that the red landrace selections emerged better (P<0.001) than the light-brown and brown landrace selections, respectively. Plant growth was lower under irrigated compared with rainfed conditions. Stomatal conductance was higher (P<0.001) under irrigated compared with rainfed conditions, whereas chlorophyll content index was higher (P<0.05) under rainfed compared with irrigated conditions. Results of the pot trial showed that emergence was significantly (P<0.001) affected by temperature. It was higher at 33/27°C compared with 21/15°C (P<0.001). Dark-coloured landraces had higher emergence compared with the light-brown landraces. Stomatal conductance was lower at 30% ET relative to 100% ETc. There were no significant differences between water regimes with respect to biomass, pod number per plant, pod mass per plant, seed number per pod, seed mass per plant and harvest index. It is concluded that seed colour is an important variable in the identity of bambara landraces. Provenance plays a significant role in seed performance and there is a significant interaction between provenance and seed coat colour. This study could be expanded to obtain more data for crop improvement through inclusion of many sites and seasons for better agronomic advice to farmers. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

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.

Local maize landraces have evolved over hundreds of years of natural and farmer selection under varying conditions. These landraces may have developed tolerance to abiotic stresses such as water deficits during this cycle of selection. However, despite its continued existence and importance, little is known on their agronomy and responses to water stress. If indeed landraces have developed tolerance to water stress, they may prove a key genetic resource for future crop improvement in light of increasing water scarcity. The primary objective of this study was to evaluate the responses of a local maize landrace to water stress at different stages of growth in comparison to two known commercial hybrids, SC701 and SR52. Seed from a local maize landrace was multiplied and characterised according to kernel colour. Two distinct colours were selected for the purposes of this study, white (Land A) and dark red (Land B). In a holistic approach, the thesis consisted of four separate studies whose overall objective was to evaluate the responses of the maize landraces to water stress at different growth stages, up to and including yield and its components. These comprised three controlled environment studies (25°C; 60% RH) and a field trial. For the controlled environment, two water regimes were used, 25% field capacity (FC) (stress treatment) and 75% FC (non-stress). The first study investigated the effect of water stress on early establishment performance. Seed quality was evaluated using the standard germination test together with electrolyte leakage. Catalase activity and accumulation of proline were examined as seedling physiological response to water stress. The second study was conducted as a pot trial to investigate the effect of water stress on growth, photosynthesis and yield. Photosynthesis was measured as chlorophyll fluorescence (CF). In addition, a field study over three planting dates was conducted at Ukulinga Research Farm in Pietermaritzburg, under dryland conditions, during the period from August 2008 to June 2009. The objective was to evaluate the effect of planting dates and changing soil water content on growth, yield and yield components. Three planting dates were used, representative of early (28 August 2008), optimum (21 October 2008) and late planting (9 January 2009). Lastly, a study on hydro-priming was conducted, necessitated by observations made primarily in the first study. The study was carried out under controlled environment conditions. The objective was to evaluate whether hydropriming can improve germination, vigour and emergence under water stress. Seeds were soaked in water for 0 hours (Un-primed or control), 12 hours (P12) and 24 hours (P24). Results from the first study showed that maize landraces were slower to germinate and emerge, and produced less vigorous seedlings compared to the hybrids. The study showed that hybrids were more superior under optimum (75% FC) conditions than under stress conditions (25% FC). Physiological showed that both hybrids and landraces expressed catalase under water stress, with landraces showing slightly better expression compared to the hybrids. Proline accumulation was observed in both hybrids and landraces as a response to water stress, with hybrids being more sensitive to water stress. In the pot trial, results showed that the vegetative stage of both hybrids and landraces was less sensitive to water stress than the reproductive stage. Results showed no differences between field capacities, with respect to emergence, mean emergence time, leaf number, CF, ear prolificacy and ear length. Photosynthesis, as measured by CF, was shown to be desiccation tolerant. Water stress had a negative effect on cob mass, lines per cob, grains per cob and total grain mass, and resulted in barrenness in the landraces. The hybrids had superior yield compared to the landraces. Results for the field trials showed that planting date had highly significant effects on emergence, plant height, leaf number and days to tasseling (DTT). Landraces emerged better than hybrids in all plantings; highest emergence was in the early and late plantings. Optimum and late planting resulted in maximum plant height and leaf number, respectively, compared to early planting. Hybrids were superior, growing taller and with more leaves than landraces in all plantings. DTT decreased with successive plantings. Planting date had an effect on ear prolificacy (EP), kernels/ear (KNE) and 100 grain mass. Planting date had no effect on ear length and mass, kernel rows/cob, grain mass and yield. With the exception of EP, hybrids out-yielded the landraces in all three planting dates. Hydro-priming landraces for 12 hours and 24 hours, respectively, improved germination velocity index, reduced mean germination time and improved emergence and mean emergence time of maize landraces under water stress. Performance of hybrid seeds remained superior to that of landraces even after seed treatment to improve germination and vigour. Landraces were slower to germinate and emerge and produced less vigorous seedlings in controlled conditions only. Both hybrids and landraces expressed catalase activity and also accumulated proline in response to water stress, although hybrids were more sensitive to stress in the establishment phase. Results confirmed literature, showing that, for both hybrids and landraces, the vegetative stage is less sensitive to stress than the reproductive stage. Hybrids produced superior yields compared to landraces in both controlled environment and field conditions. However, the pattern of seedling establishment observed in the initial controlled environment study for hybrids and landraces was reversed in the field study. Lastly, hydro-priming is of some benefit to maize establishment. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

The fish community structure of two contrasting estuaries, one with a well developed mangrove forest (Mngazana) and the other without mangroves (Mngazi) was compared. Both the Mngazi and Mngazana estuary fish communities were dominated by marine species, reflecting the importance of these systems as nursery areas for marine fishes. The Mngazi Estuary contained 18% more estuarine fishes in terms of catch per unit effort (CPUE) than the Mngazana Estuary. The reduced tidal influence due to the narrow mouth opening is a possible reason for the heightened CPUE of estuarine species in the Mngazi estuary. The recorded higher diversity of fish species in the Mngazana Estuary when compared with the Mngazi Estuary was attributed to the greater influence of the marine environment due to the wide permanently open mouth, as well as the presence of a variety of habitats in this system. In both estuaries tropical and temperate species were captured, confirming the transitional nature of their biogeographic location which is situated close to the boundary between the subtropical and warm temperate regions of the Southern African coastline. Contrary to previous studies, which recorded seasonal changes in the proportions of tropical and temperate species, the proportions of tropical species remained unchanged at approximately 70% during the January and June sampling occasions. Global warming as a possible reason for the increased dominance of tropical species is discussed. Although several studies in southern Africa have investigated estuarine food web structure, none have compared mangrove and non-mangrove estuaries. In this study, the primary sources of carbon utilised by the fish fauna in the Mngazi and Mngazana estuaries was investigated. The carbon isotopic values of fishes in both estuaries displayed a continuum rather than a tight clustering around particular energy sources. Most detritus feeders of the family Mugilidae (mullets) from both estuaries were relatively more enriched than other fish taxa. The isotopic values of the mullet species suggest a diet derived from relatively enriched carbon sources such as benthic microalgae, the eelgrass Zostera capensis and associated epiphytes. Based on the isotopic values, piscivorous fishes from both estuaries could not be linked to specific prey fish taxa, but clearly the mullet species were not their main food source. The invertebrate feeders that were found in both estuaries showed greater isotopic variations in the Mngazana Estuary than in the Mngazi Estuary, probably reflecting the higher diversity of habitats (carbon sources) and invertebrate prey species in the Mngazana system. Generally the isotopic signatures of fishes from the Mngazi Estuary were more enriched than those from the Mngazana Estuary, thus indicating the possible effect of δ¹³C depleted mangrove derived carbon in the latter system.

Recent research conducted throughout the Northern California Current (NCC) on the ecology of Pacific salmon (Oncorhynchus spp.) indicates that variable ocean conditions affect the community composition of zooplankton in the nearshore environment which, in turn, can affect the quality of prey for fish, sea birds and mammals. Interannual variability in the quality and composition of the copepod community in the NCC during early marine residency of some Pacific salmon populations is related to survival to adulthood. However, copepods make up a small portion of the diet of coho and Chinook salmon, and the mechanistic linkages between ocean climate, zooplankton composition and salmon prey remain unclear. Parasite analysis provides a supplement to traditional diet analysis that can describe the foraging history of a host species. Coho salmon (O. kisutch) and Chinook salmon (O. tshawytscha) serve as hosts to an array of marine parasites acquired through consumption of infected intermediate hosts such as copepods, euphausiids, and planktivorous fishes. Causing little or no harm to their salmon host, the presence of trophically transmitted parasites provides information on the dietary history of their salmonid host beyond the 24 hours associated with traditional diet analysis. This study (1) examined differences in feeding behavior of coho and Chinook salmon during their early marine residency using both stomach and parasite community analyses and (2) tested the hypothesis that variability in ocean circulation patterns (measured through the Pacific Decadal Oscillation, sea surface temperature (SST) and Bakun's upwelling index) and copepod species composition are related to variability in the community structure of trophically transmitted marine parasites found in juvenile salmon. I compared the abundance and species composition of parasites recovered from juvenile Columbia River coho and upper Columbia River summer and fall Chinook salmon captured off the coast of Washington from 2002 to 2009. I also compared interannual variability in parasite assemblages to physical and biological indices of ocean conditions. Coho and Chinook salmon consumed similar prey taxa; however, the species richness and abundance of trophically transmitted parasites indicated that Chinook salmon consumed a greater diversity and abundance of infected prey. In addition, differences in the abundance of fish in the diet and Anisakis simplex, a parasitic nematode known to infect salmon through fish consumption, suggest that Chinook salmon consistently consumed more fish prey than coho. In contrast, coho appeared to consume more euphausiids as indicated by stomach content analysis and increased abundance of the euphausiid parasite, Rhadinorhynchus trachuri. Shifts in the parasite community composition of both coho and Chinook salmon were related to interannual variability in SST and the biomass of southern-origin copepods (r > 0.7, P < 0.05). The acanthocephalan R. trachuri and a tetraphyllid cestode were associated with "warm" SSTs and greater biomass of lipid-poor, subtropical copepods while the nematode A. simplex was more abundant in years of "cold" SST and a relatively low biomass of subtropical copepods. These results provide novel insight into differences in the diet of Columbia River coho and Chinook salmon and illustrate linkages between ocean climate, zooplankton community composition and salmon diet during early marine residency. / Graduation date: 2012