Stormwater runoff is a major environmental concern, particularly in urban environments. Trends in managing stormwater have evolved (and continue to evolve) from a quantity only approach into a sustainable approach, which integrates quantity, quality, the environment, and aesthetics. Best management practices (BMPs) and Low Impact Development (LID) are two well-documented techniques capable of managing to sustainable standards. There are a number of stormwater models available to design professionals today. However, there are few which integrate site-scale BMP/LID analysis in a simplified fashion. The purpose of this study is to determine if there is a demand in the design profession for simplified stormwater modeling tools to help designers make informed decisions about integrating BMP/LID strategies into site plans. A Web-based questionnaire was administered to a group of design professionals to determine their knowledge of BMPs and their technological needs and preferences in meeting stormwater goals and requirements.

Oxidative storage stability was conducted to determine the optimum antioxidant for the production of catfish methyl esters (CFME) for use as biodiesel. Peroxide value, anisidine value, 2-thiobarbituric reaction substances, acid value, iodine value, UV absorbance, and induction period were measured. Antioxidant, stability parameters changed over a storage time of one year when stored at 25°C. The CFME were not stable to oxidation without the addition of TBHQ. When stored at 25°C, oxidative parameters indicated that CFME was a stable product that met oxidative stability standards when TBHQ was added. When held at 80°C for 28 days, the samples with TBHQ were stable to oxidation. However, the acid value rose above the maximum at 28 days. Thus, CFME can be stable to oxidative breakdown when THBQ was added at 800 ppm, but when exposed to high temperatures, one will have to limit water or protect CFME against hydrolytic rancidity.

The importing of tra, basa, and channel catfish at relatively lower prices has resulted in less catfish purchased from U.S. farmers and processors. Claims have been filed with the U.S. International Trade Commission (ITC) accusing Vietnamese exporters of selling catfish to the U.S. at less than fair market value. Consequently, the U.S. International Trade Commission ruled against Vietnam in 2003 and recommended tariffs from 37% to 64%. The primary objective of this research is to assess the impact of the tariffs on imported Vietnamese catfish on the U.S. catfish industry. In this study, we develop a supply and demand model of the U.S. catfish industry at the farm and wholesale level. In this model, we incorporate the effects of imports and estimate the short-run and long-run effects of changes in import prices on U.S. prices, quantities and welfare at the farm and wholesale level.

Planorbella trivolvis, a snail routinely found in catfish ponds, is an intermediate host in the life cycle of Bolbophorus damnificus, a digenetic trematode responsible for mortalities in catfish. This research generated information on the life cycle and the population dynamics of P. trivolvis in catfish ponds which could be implemented to control P. trivolvis. Research indicated that: P trivolvis is present year-round; survives overwintering at water temperatures of 5°C; reproduces year-round; is found in vegetation, sediment and water in ponds year-round; lays eggs two months post-hatch; and has a life span of at least one year. Planorbella trivolvis infected with Bolbophorus spp. were found in 0.8% of the snails examined; found in juvenile snails (4 mm), and could shed 3,200 cercariae/day, and shed these cercariae for up to 21 days. This data indicated that constant snail monitoring and persistent snail control is imperative to control P. trivolvis in catfish ponds.

Channel catfish (Ictalurus punctatus) are raised for aquaculture in ponds characterized by dramatic swings in dissolved oxygen concentration. If morning dissolved oxygen concentration falls below approximately 3.0 mg/L catfish consume less feed, leading to a reduction in growth and production. Although the effects of low oxygen on channel catfish appetite have been described, the underlying mechanisms responsible for those effects are unknown. Increased production of the neuropeptides corticotropin-releasing factor (CRF) and urotensin I (UI) are implicated in other fishes as neuropeptides that reduce appetite once an environmental stressor is detected. This project characterizes the hematological responses and transcriptional response of the hypothalamus to acute, chronic, and cyclical (repeating periods of hypoxia and normoxia) hypoxia. During acute (12 hours) hypoxia, venous PO2 decreased within 6 hours, coupled with an increase in hematocrit and decreased blood osmolality. These changes reversed within 12 hours after returning to normoxia but were not coupled with a change in transcription of the genes for CRF and UI. If this pattern of hypoxia and normoxia is repeated cyclically for 5 days, the same physiological responses repeat continually. During chronic hypoxia up to 5 days in duration, channel catfish have a similar hematological response, but did not recover to normoxic control values over the duration of the challenge. Likewise, no significant change in gene expression of CRF or UI were detected during chronic hypoxia. The hypothalamic transcriptome was analyzed during a 12-hour exposure to hypoxia followed by a 12-hour normoxic recovery. Across all time points, 190 genes were differentially expressed, with the greatest numbers occurring during periods of hypoxia. Differentially expressed genes were grouped into Gene Ontology biological processes and were most overrepresented by the term “response to hypoxia,†which included genes involved with angiogenesis, red blood cell production, and negative feedback to hypoxia-inducible factor proteins. Although this study did not find a change in hypothalamic transcription of CRF and UI, it did identify multiple adaptive responses that work together to reduce the severity of hypoxia along with several gene candidates for future hypoxia studies.

Commercial catfish production is an inveterate industry within the southeastern United States. Bacterial disease is a significant detriment to global aquaculture, including the United States catfish industry. Among them, an atypical strain of the bacterium Aeromonas hydrophila has plagued the industry since the late 2000s. Atypical A. hydrophila (aAh) outbreaks are largely acute, resulting in catastrophic losses. The disease ecology, prevalence, and genetic distribution are poorly understood. Atypical Aeromonas hydrophila displays a rapid onset with few warning signs of the impending disease, making it difficult for early detection. At present there are two recognized haplotypes of aAh. This project aimed to investigate changes in the spatial and temporal distributions of these haplotypes. The analysis of clinical isolates from different geographic regions across multiple years revealed complete supplanting by the younger haplotype in the Mississippi Delta within 5 years of first isolation. Comparative genomics demonstrated distinct divergences in specific virulence components between the two strains, specifically the Type VI Secretion System, which may explain putative differences in outbreak dynamics and recent displacement of one strain by the other. Also, a rapid, non-lethal screening method was validated that can detect aAh within the catfish host. This method affords data collection regarding infection severity prior to onset of disease and, can predict aAh prevalence at the fish- and pond-levels. The occupancy model indicates more than half the population within a pond may be infected with aAh despite no overt signs of disease. Additionally, aAh is commonly present in approximately 10% of the population, providing the first evidence of a carrier state in this disease. Lastly, a compartmental SLIR model was used to investigate disease dynamics of aAh in catfish aquaculture ponds. Simulations suggest the introduction hypothesis does affect estimated pond profit and antibiotic intervention is an economical treatment for aAh. Routine monitoring was less economical and could dramatically reduce profit in some scenarios. Overall, this work expands our current knowledge of aAh in catfish aquaculture and lays the foundation for future studies investigating aAh management and mitigation of bacterial disease in catfish aquaculture.

This thesis is concerned with the study on the effect of the swimbladder on hearing sensitivity in Ameiurus nebulosus. The investigation has been performed by means of auditory threshold curves in normal catfish and in catfish in which the resonance of the swimbladder was eliminated. The results were compared. The thesis consists of an introduction to the investigation, followed by a review of the literature in relation to the problem, a description of the material and technique and of the experimental work, the results obtained with a discussion and a summary. / Thesis / Master of Science (MSc)

This study was designed to develop a method of rapidly evaluating dietary proteins for channel catfish (Ictalurus punctatus) and to gain basic knowledge of its nitrogen metabolism with respect to dietary protein quantity and protein quality. Experiments l, 2 and 3 were short-term (7-week) growth trials with fingerling catfish in aquaria under controlled laboratory conditions. Parameters measured each week included instantaneous daily gain of the fish (IDG) and the activities of selected enzymes - glutamate dehydrogenase (GDH), aspartate aminotransferase (GOT), alanine aminotransferase (GPT) and alkaline phosphatase (AP). Fish were fed purified diets differing in protein quantity and protein quality in experiments 1 and 2, respectively. GDH, GOT, GPT and AP activity and IDG increased with increased dietary protein quantity. The consistency of the relationship between enzyme activity and IDG decreased as follows: GOT, GDH, GPT and AP. GOT activity and IDG increased, and GDH activity decreased, with increased dietary protein quality. IDG was positively correlated to GOT activity and negatively correlated to GDH activity. GPT activity was unrelated to either dietary protein quality or IDG. GDH and GOT activity responded to changes in dietary proteins within 3 weeks in experiments 1 and 2. The ratio of GOT activity to GDH activity was positively correlated to dietary protein quality. The growth and enzyme activity data from experiments 1 and 2 were used to develop indices of growth based on enzyme activity. The growth indices were tested as a method of rapidly evaluating dietary proteins in experiment 3 where fish were fed natural ingredient diets differing in protein source. The proteins included fish meal and four types of seafood processing wastes. GDH, GOT and GPT activity, the GOT/GDH ratio, IDG and the growth indices were similar among treatments in catfish fed different protein sources at 10 percent of the diet in experiment 3. The results of experiment 3 could not be used to adequately assess the growth indices and the GOT/GDH ratio but did indicate the feasibility of using seafood processing wastes as fish meal substitutes at 10 percent of the diet. / Ph. D.

Thesis (Ph.D.) -- Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Basic Sciences. / Title from title screen. Includes bibliographical references.