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You searched for +publisher:"Texas State University – San Marcos" +contributor:("Bonner, Tim"). Showing records 1 – 2 of 2 total matches.

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Texas State University – San Marcos

1. Gold Quiros, Taylor Rene. Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position.

Degree: MS, Aquatic Resources, 2018, Texas State University – San Marcos

Mercury (Hg) is known to bioaccumulate over time in freshwater fish and biomagnify up freshwater food webs, so top predatory fish have the highest Hg body burden. Within Texas, Hg studies in freshwater fish have primarily focused on the northern half of the state and south Texas is relatively understudied. This study investigated the concentration of Hg in muscle tissue from 41 trophically diverse species (n = 1,772) in relation to body length and trophic position at five sites on the Guadalupe River in South Central Texas using a direct mercury analyzer and stable isotope analysis (δ13C, δ15N). The majority of fishes showed a positive relationship between body length and Hg concentration, indicating that Hg was bioaccumulating over time. Striped mullet was the only species that displayed an inverse relationship suggesting growth dilution is occurring. Mercury concentrations were higher in top predators including longnose gar, flathead catfish, and striped bass, and lower in moderate and low trophic level fishes, including Mexican tetra, threadfin shad, and suckermouth catfish. Within the five sites examined, the average Hg concentration in each species was higher in reservoir sites than riverine sites. There was a positive relationship (p < 0.05) between δ15N and Hg concentration at 4 of the 5 sites, indicating that Hg biomagnification is occurring at these sites. The biomagnification factor differed between sites, however it was not positively correlated with food chain length. Among species, the estimated trophic level was the strongest predictor of Hg concentration and within species, total length was the strongest predictor of Hg concentration. These findings provide valuable insight into bioaccumulation and biomagnification of Hg in a relatively understudied freshwater system in South Central Texas. Four species (flathead catfish, white bass, striped bass and longnose gar) had at least one individual that exceeded the Texas Department of State Health Services (TDSHS) human health criterion for Hg (0.7 µg/g wet weight), with at least one species at Canyon Lake, Lake Dunlap, and Victoria exceeding the guideline. Based on this data, the current Hg advisory for Canyon Lake needs to be reevaluated and Victoria and Lake Dunlap may need to have Hg advisories issued. Advisors/Committee Members: Dutton, Jessica (advisor), Bonner, Tim (committee member), Nowlin, Weston (committee member), Robertson, Clint (committee member).

Subjects/Keywords: Mercury; Fish; Texas; Trophic level; Reservoir; Risk assessment; Fishes – Mercury content – Texas – Guadalupe River

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gold Quiros, T. R. (2018). Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position. (Masters Thesis). Texas State University – San Marcos. Retrieved from https://digital.library.txstate.edu/handle/10877/7876

Chicago Manual of Style (16th Edition):

Gold Quiros, Taylor Rene. “Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position.” 2018. Masters Thesis, Texas State University – San Marcos. Accessed August 23, 2019. https://digital.library.txstate.edu/handle/10877/7876.

MLA Handbook (7th Edition):

Gold Quiros, Taylor Rene. “Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position.” 2018. Web. 23 Aug 2019.

Vancouver:

Gold Quiros TR. Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position. [Internet] [Masters thesis]. Texas State University – San Marcos; 2018. [cited 2019 Aug 23]. Available from: https://digital.library.txstate.edu/handle/10877/7876.

Council of Science Editors:

Gold Quiros TR. Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position. [Masters Thesis]. Texas State University – San Marcos; 2018. Available from: https://digital.library.txstate.edu/handle/10877/7876


Texas State University – San Marcos

2. Cummings, Greg A. Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river.

Degree: MS, Aquatic Resources, 11, Texas State University – San Marcos

Rainbow Trout Oncorhynchus Mykiss are typically stocked in tailraces across the southeastern United States to mitigate fish habitat and assemblage alterations caused by large impoundments. Hypolimnetic discharges from Canyon Reservoir have created conditions suitable for a coldwater tailrace fishery and trout have been stocked there since 1966. Changes in habitat availability for adult Rainbow Trout with discharge rate were examined to provide flow and habitat improvement recommendations for the Canyon Reservoir tailrace. Physical habitat modeling incorporated habitat suitability information for trout coupled with hydraulic modeling to assess habitat quality and quantity at various flow rates. Habitat mapping included traditional surveying, remote sensing, bathymetric mapping, and side scan sonar. Side scan sonar was evaluated for efficiency and applicability to river systems similar to the tailrace. Results indicate that summer water temperature is likely the primary limiting factor for adult trout survival and could impose limitations on physical habitat during critical summer months. Modified flow rates and habitat improvement could cause a potential increase in adult trout abundance and assist put-grow-and-take strategies in the upper portion of the tailrace. Side scan sonar provided efficient mapping of non-wadable sections of the study area. Challenges related to water level, access, navigability, positional accuracy, and post-processing were overcome. Trial runs, training, map accuracy assessments, and technological development will improve the effectiveness of this technique. Advisors/Committee Members: Hardy, Thom B. (advisor), Bonner, Tim (committee member), Kaeser, Adam (committee member).

Subjects/Keywords: Rainbow trout; Habitat suitability; Habitat availability; Canyon Reservoir; Tailrace; PHABSIM; Side scan sonar; Hydraulic modeling; Rainbow trout – Habitat – Texas; Canyon Lake (Comal County, Tex.) : Lake

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cummings, G. A. (11). Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river. (Masters Thesis). Texas State University – San Marcos. Retrieved from https://digital.library.txstate.edu/handle/10877/5893

Chicago Manual of Style (16th Edition):

Cummings, Greg A. “Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river.” 11. Masters Thesis, Texas State University – San Marcos. Accessed August 23, 2019. https://digital.library.txstate.edu/handle/10877/5893.

MLA Handbook (7th Edition):

Cummings, Greg A. “Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river.” 11. Web. 23 Aug 2019.

Vancouver:

Cummings GA. Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river. [Internet] [Masters thesis]. Texas State University – San Marcos; 11. [cited 2019 Aug 23]. Available from: https://digital.library.txstate.edu/handle/10877/5893.

Council of Science Editors:

Cummings GA. Habitat suitability and availability for Rainbow Trout (Oncorhynchus mykiss) in the Canyon Reservoir tailrace and evaluation of side scan sonar for habitat mapping in a semi-wadable river. [Masters Thesis]. Texas State University – San Marcos; 11. Available from: https://digital.library.txstate.edu/handle/10877/5893

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