Global ETD Search

71	Responses of Selected Texas Fishes to Abiotic Factors, and an Evaluation of the Mechanisms Controlling Thermal Tolerance of the Sheepshead Minnow Bennett, Wayne A. (Wayne Arden) 05 1900 (has links) Low oxygen tolerances of ten fishes were estimated using an original nitrogen cascade design, and reciprocally transformed to express responses as ventilated volume necessary to satisfy minimal oxygen demand (L·mg O2^-1). Values ranged from 0.52 to 5.64 L·mg^-1 and were partitioned into three statistically distinct groups. Eight stream fishes showed moderately high tolerances reflecting metabolic adaptations associated with stream intermittency. Juvenile longear sunfish and two mollies comprised the second group. High tolerance of hypoxia may allow juvenile sunfish to avoid predation, and mollies to survive harsh environmental oxygen regimens. The sheepshead minnow was the most tolerant species of low oxygen, of those examined, explaining its presence in severely hypoxic environments. fishes thermal tolerance sheepshead minnow Fishes -- Ecology -- Texas. Oxygen -- Physiological effect. Fishes -- Effect of temperature on. Freshwater drum -- Texas.
72	Brain morphology and behavioural variation in relation to habitat and predation risk in minnows (Phoxinus phoxinus) Gallego González, Marina January 2022 (has links) So far, research on inter- and intraspecific teleost brain plasticity across different freshwater environments has been widely conducted. However, insights of brain morphological variation on social and predator avoidance behaviours are lacking. Here, we investigated variation in shape and size of the brain and its six major regions of European minnows (Phoxinus phoxinus) inhabiting Lake Ånnsjön and its tributaries, using geometric morphometrics methods. We also experimentally compared stream and lake fish activity and social behaviour under different feeding and predation regimes. Contrary to our predictions of lake minnows having evolved smaller brains because of living in habitats with reduced environmental complexity compared to their conspecifics in the streams, we found that overall brain size generally did not differ between locations. Instead, brain morphology differed between minnows caught in the lake and streams, with stream minnows showing larger dorsal medulla, telencephalon and olfactory bulbs, and lake minnows presenting larger optic tecta and hypothalamus. Experimental results showed that lake minnows were more likely to engage in social behaviour than those from streams. Our results indicate that while overall allocation of energy to the brain does not change, habitat-specific differences in activity and trophic divergence might predict specialization for different senses, allocating more resources towards different brain regions. In addition, we show how various ecological factors, such as environmental complexity and social organization seem to be reflected in brain shape. brain size Ecology environmental complexity European minnow fish geometric morphometrics morphological divergence phenotypic plasticity schooling. Ecology Ekologi
73	Assessment of the Efficacy of a Constructed Wetland to Reduce or Remove Wastewater Effluent Estrogenicity and Toxicity Using Biomarkers in Male Fathead Minnows (Pimephales Promelas Rafinesque, 1820) Hemming, Jon M. 12 1900 (has links) Vitellogenin in Pimephales promelas was used to assess estrogenicity of a local municipal effluent. Vitellogenin induction in male P. promelas increased in frequency and magnitude with increased exposure duration and was greater ("=0.05) than controls after 2 and 3 weeks of exposure. The level of vitellogenesis induced by effluent exposure was high compared to similar studies. A spring season evaluation followed. Biomarkers in P. promelas were used to assess the efficacy of a treatment wetland to remove toxicity and estrogenicity in final treated wastewater effluent. Comparisons were made with an effluent dominated stream and laboratory controls. Vitellogenin, GSIs (gonado-somatic indices), HSIs (hepato-somatic indices) and secondary sexual characteristics were biomarkers used in P. promelas models to assess aqueous estrogenicity. Biological indicators used to assess general fish health included hematocrit and condition factors. The estrogenic nature of the effluent was screened, concurrent with fish exposure, with GC/MS analysis for target estrogenic compounds including: 17-b estradiol, estrone, ethynylestradiol, Bisphenol A, nonylphenolic compounds, phthalates, and DDT. Plasma vitellogenin measured in P. promelas was significantly elevated (p < 0.0001) at the inflow site of the wetland and stream sites. GSIs for these exposures were less (a=0.001) at the wetland inflow site. At wetland sites closest to the inflow, secondary sexual charateristics, tubercle numbers and fat pad thickness, were less (a=0.0001). Hematocrit and condition factors were less (a=0.001) at sites closer to the wetland inflow. Seasonal variation was examined by repeating the effluent characterization in summer. Additionally, summer testing included exposure to an effluent dilution series. Fish condition heavily influenced interpretation of the results. Pre-acclimation exposure to spawning stresses may have altered many of the biological markers measured. Results are discussed relative to fish health and pre-exposure environment. Toxicity assessed with P. promelas biomarkers was compared with Ceriodaphnia dubia and Vibrio fischeri toxicty tests on this effluent. Biomarkers of fish health were somewhat less sensitive than C. dubia test endpoints, but more sensitive than V. fisheri. Effluent quality. Biochemical markers. Estrogen -- Environmental aspects. Wetland ecology. Vitellogenin xenoestrogens wastewater effluent Pimephales promelas constructed wetland
74	The Sub-Chronic Effects of Polycyclic Aromatic Hydrocarbons on the sheepshead minnow (Cyrpinodon variegatus) Gut-Microbiome and Foraging Behavior Maggie A Wigren (8741202), Timothy A. Johnson (2384710), Robert J. Griffitt (241837), Marisol S. Sepúlveda (2919935) 24 April 2020 (has links) The microbiome plays a key symbiotic role in maintaining host health and aids in acquiring nutrients, supporting development and immune function, and modulating behavior. However, more research is needed to elucidate the potential impact of environmental pollutants on host microbial communities and how microbiomes can modulate the toxicity of contaminants to the host. Through a literature review of 18 studies that assessed the impacts of various anthropogenic chemicals on fish-associated microbiomes, we found that toxicants generally decrease microbial diversity, which could lead to long-term health impacts if chronically stressed, and can increase the host’s susceptibility to disease as well as the chemical resistance of certain microbes. These findings led us to explore the impacts of one of the reviewed contaminants, polycyclic aromatic hydrocarbons (PAHs), typically found in oil. The Deepwater Horizon disaster of April 2010 was the largest oil spill in U.S. history and had catastrophic effects on several ecologically important fish species in the Gulf of Mexico (GoM). This study tested the hypotheses that exposure to weathered oil would cause significant shifts in fish gut-associated microbial communities, with taxa known for hydrocarbon degradation increasing in abundance and that foraging behavior would decrease, potentially due to microbial dysbiosis via the gut-brain axis. We characterized the gut microbiome (with 16S rRNA gene sequencing) of a native GoM estuarine species, the sheepshead minnow (Cyprinodon variegatus). Fish were exposed to High Energy Water Accommodated Fractions (HEWAF; tPAH = 80.99 ± 12.5 μg/L) of oil over a 7-day period and whole gastrointestinal tracts were sampled for microbiome analyses. A foraging behavioral assay was used to determine feeding efficiency before and after oil exposure. The fish gut microbiome did not experience any significant changes in alpha or beta diversity but known hydrocarbon degrading taxa were noticeably present in oil-exposed communities and were absent in controls. We found the order Pseudomonadales, the family Paenibacillaceae, and Pseudomonas pachastrellae to be among these, with Pseudomonadales increasing in abundance. Foraging behavior was not significantly affected by oil exposure. This work highlights the need for further research to elucidate the functional metagenomic responses of the fish gut-microbiome under oil spill conditions. Bioinformatics Ecology not elsewhere classified Genomics Microbial Ecology Animal Behaviour Polycyclic Aromatic Hydrocarbons (PAHs) Deepwater Horizon Microbiome Foraging behavior
75	Photo-Induced Toxicity and Toxicokinetics of Single Compounds and Mixtures of Polycyclic Aromatic Hydrocarbons in Zebrafish and Sheepshead Minnow Willis, Alison Micha 05 July 2013 (has links) No description available. Aquatic Sciences Biology Environmental Science Experiments Toxicology Zoology polycyclic aromatic hydrocarbon (PAH) toxicokinetics LC50 carbazole phenanthrene anthracene pyrene fluoranthene phototoxicity mixtures toxic unit (TU) zebrafish sheepshead minnow risk assessment
76	Cardiotoxic effects of polycyclic aromatic hydrocarbons and abiotic stressors in early life stage estuarine teleosts Elizabeth B Allmon (10724124) 29 April 2021 (has links) <div>Following the 2010 Deepwater Horizon oil spill, extensive research has been conducted on the toxicity of oil and polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment. The location and timing of the Deepwater Horizon surface slick coincided with the spawning seasons of many important pelagic and estuarine fish species. As such, there has been particular emphasis placed on the effects of PAHs on sensitive life history stages in fish, such as the embryonic and larval periods. Additionally, the spill occurred throughout the spring and summer months which, in estuaries, are marked by regular fluctuations in abiotic environmental factors such as dissolved oxygen, salinity, and temperature. Until recently, there has been little work done to elucidate the combined effects that PAHs from oil spills and adverse environmental conditions (hypoxia, increased salinity, and elevated temperatures).</div><div>Work presented in this dissertation uses next generation sequencing technology (RNA Seq) to determine differential gene expression in larval estuarine teleosts following exposure to adverse environmental conditions and PAHs. Downstream canonical pathway and toxicological function analysis were then applied to the identified differentially expressed genes (DEGs) to predict cardiotoxic responses at the organismal level. To verify the predicted responses, a phenotypic anchoring study was conducted and identified a cardiotoxic phenotype (pericardial edema) and reduced cardiac output in embryos exposed to oil. Finally, the mechano-genetic interplay governing the morphological development of the teleost heart was investigated and correlations between developmental gene expression and blood flow forces within the cardiovascular system were identified.</div> Molecular Biology Physiology Toxicology Developmental Biology Marine Biology Bioinformatics Genomics polycyclic aromatic hydrocarbons hypoxia Deepwater Horizon Cardiac Development estuarine fish species transcriptomics Cardiac output Fundulus grandis Gulf killifish Cyprinodon variegatus sheepshead minnow Japanese medaka Oryzias latipes mechano-genetics teleost gene expression PAHs RNASeq early life history embryo larval fish
77	The Effect of Dredging on Fish Communities in Agricultural Streams in Crawford, Sandusky and Seneca Counties of Ohio. Selden, Justin D. 27 November 2013 (has links) No description available. Agriculture Animals Aquaculture Aquatic Sciences Animal Sciences Biology Biostatistics Conservation Ecology Environmental Geology Environmental Science Environmental Studies Geology Geobiology Hydrology Natural Resource Management Organismal Biology Sustainability Wildlife Conservation Wildlife Management Zoology Agriculture fish community morphology stream ditch river shiner minnow darter sunfish chub stoneroller dace topminnow Shannon Diversity Simpson's Index IBI Index of Biotic Integrity Richness Abundance dredge coefficient of variation

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