The main objective of this study was to investigate small-bodied fish caging as an approach to evaluate selenium (Se) bioaccumulation and speciation in native fish species inhabiting lakes influenced by uranium (U) milling effluent in northern Saskatchewan, Canada. In contaminated environments freshwater fish show a high propensity to accumulate Se beyond levels needed for normal physiological function. Maternal transfer of elevated Se concentrations to offspring can cause deformities and reduced survival in fry, and in certain cases negatively impact the sustainability of native fish populations. This research included a caging validation study using wild, naïve (i.e., collected from a reference lake) lake chub (Couesius plumbeus) and spottail shiner (Notropis hudsonius), and three field based 21-day caging studies to investigate the dominance of the feeding pathway with respect to Se uptake and speciation in wild populations of northern small-bodied fish exposed to a gradient of Se. Three feeding regimes were used: an in situ benthic diet, a basal Se diet of Chironomus dilutus (1.5 µg Se/g dry weight) and a Se-spiked diet of C. dilutus (5.5 µg Se/g dry weight). Lake chub were identified as more suitable candidates for caging due to higher survival and condition factor at the completion of the in situ 21-day trial. The resulting Se bioaccumulation was compared among treatments as well as to wild small-bodied fish populations from the study area. Results from the caging experiments showed that caged lake chub exposed to natural and controlled diets with elevated Se had significantly greater whole-body Se concentrations after 21 days compared to fish caged in the reference lake. The results also showed that whole-body Se concentrations exceeded conservative Se thresholds, and approached the currently proposed USEPA regulatory threshold (7.91 µg/g dry weight) designed to protect fish species in only three weeks. The use of stable carbon (C), nitrogen (N), and sulphur (S) isotope ratios indicated that alternate benthic food sources native to the exposure lake were consumed in conjunction with the controlled diets. Stable isotope analysis of both wild and caged lake chub indicated that the N and S isotopic signatures decreased with increasing Se exposure, representing differences in isotopic signatures of the food sources. Speciation results from caged lake chub indicated that Se substituted for S in methionine (i.e. selenomethionine) was the dominant Se species found in caged lake chub exposed to dietary sources of elevated Se. Overall, this research demonstrates that using caged native lake chub represents a useful biomonitoring approach to investigate patterns of Se bioaccumulation and speciation in fish.

The main objective of this study was to investigate small-bodied fish caging as an approach to evaluate selenium (Se) bioaccumulation and speciation in native fish species inhabiting lakes influenced by uranium (U) milling effluent in northern Saskatchewan, Canada. In contaminated environments freshwater fish show a high propensity to accumulate Se beyond levels needed for normal physiological function. Maternal transfer of elevated Se concentrations to offspring can cause deformities and reduced survival in fry, and in certain cases negatively impact the sustainability of native fish populations. This research included a caging validation study using wild, naïve (i.e., collected from a reference lake) lake chub (Couesius plumbeus) and spottail shiner (Notropis hudsonius), and three field based 21-day caging studies to investigate the dominance of the feeding pathway with respect to Se uptake and speciation in wild populations of northern small-bodied fish exposed to a gradient of Se. Three feeding regimes were used: an in situ benthic diet, a basal Se diet of Chironomus dilutus (1.5 µg Se/g dry weight) and a Se-spiked diet of C. dilutus (5.5 µg Se/g dry weight). Lake chub were identified as more suitable candidates for caging due to higher survival and condition factor at the completion of the in situ 21-day trial. The resulting Se bioaccumulation was compared among treatments as well as to wild small-bodied fish populations from the study area. Results from the caging experiments showed that caged lake chub exposed to natural and controlled diets with elevated Se had significantly greater whole-body Se concentrations after 21 days compared to fish caged in the reference lake. The results also showed that whole-body Se concentrations exceeded conservative Se thresholds, and approached the currently proposed USEPA regulatory threshold (7.91 µg/g dry weight) designed to protect fish species in only three weeks. The use of stable carbon (C), nitrogen (N), and sulphur (S) isotope ratios indicated that alternate benthic food sources native to the exposure lake were consumed in conjunction with the controlled diets. Stable isotope analysis of both wild and caged lake chub indicated that the N and S isotopic signatures decreased with increasing Se exposure, representing differences in isotopic signatures of the food sources. Speciation results from caged lake chub indicated that Se substituted for S in methionine (i.e. selenomethionine) was the dominant Se species found in caged lake chub exposed to dietary sources of elevated Se. Overall, this research demonstrates that using caged native lake chub represents a useful biomonitoring approach to investigate patterns of Se bioaccumulation and speciation in fish.

I studied habitat preferences of Gila chub in a canyon-bound system (Bonita Creek) and a marsh system (Cienega Creek). Gila chub in Bonita Creek, frequently occurred in a broader range of habitat types and conditions than Gila chub in Cienega Creek. Gila chub in Cienega Creek were highly pool oriented. In contrast, Gila chub in Bonita Creek generally preferred, or used in proportion, swifter shallower habitat types. Segregation between size classes in relation to habitat variables was noted, but was less than expected. I studied other life-history characteristics as well and found reproduction commencing in February, peaking in spring, and dropping off as summer begins. Spawning in the fall is suggested by the presence of small YOY and gonad development. I also evaluated methods to spawn and rear Gila chub. Following initial spawning, Gila chub spawned consistently in the laboratory without hormonal, chemical, photoperiod, or drastic temperature and substrate manipulation, during all times of the year. Spawns were noted at temperatures ranging from about 15 to 26°C but spawning above 24°C occurred infrequently. Larval Gila chub fed a commercial diet grew the same or slightly better than those fed thawed Artemia sp. nauplii, and significantly better than those fed chicken Gallus domesticus egg-yolk powder, but survived significantly better when fed Artemia. Despite the latter, observations suggest Artemia nauplii may be difficult for first-feeding larval Gila chub to handle. Thawed chironomid sp. larvae clearly outperformed prepared commercial feeds for small and large juvenile Gila chub with respect to growth. Growth of larval Gila chub was highest at 28ºC and lowest at 32ºC, while survival of larval Gila chub was highest at 24ºC and lowest at 20ºC. Spinal deformities were common (about 47%) for larval Gila chub reared at 32ºC but generally uncommon for those reared at lower temperatures. Water temperatures from 20-28ºC appear suitable for rearing larval Gila chub, with temperatures from 24-28ºC more optimal. Water temperatures from 20-29ºC appear suitable for rearing juvenile Gila chub. My data strongly support increasing rearing density having a negative effect on growth and survival (larval only) of Gila chub. Although populations of Gila chub share many natural history traits, my data suggests habitat use can vary among systems. It is possible unique preferences and strategies exist between different populations of Gila chub. Thus managers should be cautious about applying information based on one population to others. The future of Gila chub may someday depend in part on hatchery propagation to provide specimens for restocking formerly occupied habitats and establishing refuge populations. Information from my study can aid future efforts to successfully spawn and rear Gila chub and related species.

No description available.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August 2007." Includes bibliographical references (leaves 40-44). Online version available on the World Wide Web.

Thesis (Ph. D.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 7, 2007) Includes bibliographical references.

M.S.

There are three recognized species of Siphateles from the Great Basin; S. alvordensis, S. boraxobius and the tui chub, S. bicolor. One species, S. boraxobius, is endangered and one population of tui chub at Hutton Spring is threatened. Despite several morphological and molecular studies, the taxonomy and relationships of tui chubs are unclear. A recurrent theme in prior studies has been the possibility of translocation of tui chubs, especially into Summer Lake Basin, and probably by bait bucket introductions. I approached this problem by using cytochrome b (cyt b) sequences to define clades and constructed a neighbor-joining tree to examine relationships. Developmental ontogeny and adult meristic characters were used to corroborate clades, and microsatellites (nDNA) used to explore the possibility of hybridization among Summer Lake Basin fish and those from surrounding basins. The cyt b tree recovered a basal polytomy containing a western clade from Sycan Marsh, an eastern clade from the Alvord Basin, and S. bicolor. The Sycan Marsh clade was represented by two fish and requires additional research. Within the Alvord Basin, S. boraxobius and S. alvordensis were well corroborated by morphological characters but sequence divergence was only 0.37%. There were three major clades in S. bicolor – a basal S. newarkensis clade in Nevada, an Oregon Lakes S. bicolor clade, and, sister to it, a disjunct S. obesa clade in Nevada and the Oregon Lakes. In the Oregon Lakes, there were two clades within S. bicolor: S. thalassinus was sister to the remaining S. bicolor and there were two clades within S. obesus: S. oregonensis was sister to a "Summer Lake Basin" clade. There was some morphological corroboration for S. oregonensis, but no corroboration for the others. Clades were geographically disjunct or not confined to single basins. The S. oregonensis clade was sister to a Nevada polytomy and historical evidence implicates that at least one population of S. oregonensis in XL Spring was introduced in the late 1800's. Average sequence divergence with the Nevada clade, 0.62 - 0.88%, did not seem to support possible Miocene or Pliocene vicariance scenarios. Elsewhere, the S. thalassinus clade was found outside of Goose Lake in Summer Lake Basin and the "Summer Lake Basin" clade was found in Goose Lake Basin. Clustering of three microsatellite loci did not match cyt b clades, rather, individuals clustered based on sample location, suggesting that the cyt b patterns were due to introgression. In Summer Lake Basin, evidence of poisoning and subsequent transplants was consistent with these observations. These results suggest the presence of three or four tui chub taxa in the Oregon Lakes and Alvord Basin, however translocation and subsequent introgression appear to have been common in many populations, and will prove challenging for taxonomists and conservation managers. / Graduation date: 2013

Humpback Chub Gila cypha are endangered cyprinids endemic to the Colorado River drainage and are adapted to live in fast currents of warm, turbid water. Although nine known aggregations of Humpback Chub currently exist in the main-stem Colorado River in the Grand Canyon, little is known about their reproduction. I hypothesized that Colorado River water temperatures below Glen Canyon Dam are too low due to hypolimnetic water releases from Lake Powell for female Humpback Chub to develop mature eggs for spawning. Ultrasonic imaging, also called ultrasound, is an effective, non-lethal method used to determine sex and maturity of a variety of freshwater, anadromous, and marine fishes. However, many previous studies have been performed in laboratory environments. I developed a standardized method for ultrasonically scanning endangered Humpback Chub Gila cypha in remote locations within Grand Canyon, Arizona, USA. This method minimized stress to individual fish and took less than 1 min to perform. I was able to identify female fish with eggs based on two jpeg images and one 10 s video clip collected in the field. I also used ImageJ®, a National Institute of Health image processing program, to develop a brightness index to evaluate the maturity of eggs in female fish. I collected ultrasonic scans of captive, ripe Humpback Chub held at the Southwestern Native Aquatic Resources and Recovery Center (SNARRC) to determine that female fish were potentially ripe when a subsample of their eggs exhibited a brightness value within the 32-44 range. Although I was able to estimate egg maturity, I was not able to estimate egg mass of female fish. I used ultrasound to evaluate reproductive condition of 751 Humpback Chub in Grand Canyon. I documented egg development in female fish from the main-stem Colorado River, Little Colorado River, Havasu Creek, and Shinumo Creek. Egg development in Humpback Chub varies by location and time of year. Potentially ripe (stage 3) female fish were found at all sample locations and dates except at Shinumo Creek in 2013 and 2014. Potentially ripe females were also detected in every main-stem aggregation except for Pumpkin Springs and in two locations outside of established aggregations. Fisheries managers can use ultrasound to collect vital information about the reproductive status of fishes that cannot be killed and that are found in remote or rugged field locations. My findings indicate that female Humpback Chub are able to produce eggs throughout the main-stem Colorado River and that internal egg development and egg production likely do not limit recruitment. However, female fish may never experience the environmental triggers they need to spawn or may not experience conditions that would allow eggs and larvae to survive.

Previous literature indicates the opercular bone as a useful tool for the determination of age and growth of fish. The reliability and validity of this method is tested for two populations of Utah chub. Age and growth are calculated for 222 Utah chub collected from Panguitch Lake and 212 Utah chub collected from Navajo Lake, southern Utah, in 1952-1953 from both scales and opercular bones. Scales are measured with the aid of a projector. Opercular bones are measured directly. The center of growth of the opercular bone is posterior to the posterior lip of the fulcrum. Correction for curvature is necessary in opercular bone measurements. The body-scale relationships for both populations are linear. The body-opercular bone relationships for both populations are slightly curvilinear. Agreement of dominant age classes for successive years, agreement of empirical length-frequency modes of young fish with calculated length-frequency modes of lower age classes, agreement of ages as indicated by scales and opercular bones, agreement of age with sexually immature fish and an increase in length with an increase in age are accepted as evidence for both methods. Opercular bones have less variation for calculated lengths in older age classes while the scales have less variation in the younger age classes. The scale method is a generally more efficient method for determining the age and growth of the Utah chub.