Selenium (Se) is known to cause chronic toxicity in aquatic species. In particular, dietary exposure of fish to selenomethionine (SeMet), the primary form of Se in the diet, is of concern. Previous studies reported that chronic exposure to elevated dietary SeMet altered swimming performance, aerobic metabolism, and energy and endocrine homeostasis in adult fish. However, little is known about the direct effects of dietary SeMet exposure in juvenile fish. Therefore, the overall objective of this thesis was to investigate sublethal pathophysiological effects of subchronic dietary SeMet exposure in two juvenile fish species, fathead minnow (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss). In the first experiment, 20 days post hatch (dph) juvenile fathead minnow were exposed to different measured concentrations (2.8, 5.4, 9.9, 26.5 µg Se/g dry mass [dm]) of Se in food in the form of SeMet for 60 days. In the second experiment, 14 dph juvenile rainbow trout were exposed for 37 days to different measured concentrations (1.0, 4.1, 11.2, 26.1 µg Se/g dm) of Se in food in the form of SeMet. Following exposure, samples were collected for Se analysis and fish were subjected to a swimming performance challenge to assess critical swim speed (Ucrit), tail beat frequency and tail beat amplitude, oxygen consumption (MO2), cost of transport (COT), standard metabolic rate (SMR), active metabolic rate (AMR), and factorial aerobic scope (F-AS). Dietary SeMet exposure impaired swimming ability in both fathead minnow and rainbow trout. Juvenile fathead minnow showed alterations in aerobic metabolism with increased MO2, COT and AMR at the 9.9 and 26.5 µg Se/g diets, while dietary SeMet exposure did not appear to affect aerobic metabolism in juvenile rainbow trout. After swim performance experiments, swam fish were considered fatigued and metabolic and energy storage endpoints were compared to non-swam (non-fatigued) fish. Energy storage capacity was measured via whole body (fathead minnow) and liver and muscle (rainbow trout) triglyceride and glycogen concentrations. For fathead minnow, triglyceride concentrations in non-swam fish were significantly elevated in the 5.4 µg Se/g group relative to controls, and swam fish had significantly lower whole body triglycerides than non-swam fish. All non-swam SeMet exposure groups had significantly decreased whole body glycogen concentrations compared to controls while the 5.4 and 26.5 µg Se/g exposure groups had significantly greater whole body glycogen concentrations in swam versus non-swam fish. In juvenile rainbow trout, liver triglyceride concentrations were significantly lower in all SeMet exposed groups compared to controls in non-swam fish. Swimming decreased liver and muscle triglycerides in the control and 11.2 µg Se/g treatment groups. Liver glycogen concentrations were greater in swam trout in the 4.1 µg Se/g dm exposure group. Muscle glycogen concentrations in non-swam fish, were significantly decreased in the 4.1 and 11.2 µg Se/g exposed groups compared to controls, while muscle glycogen in swam fish was unaffected by dietary SeMet exposure. For the swim status factor, muscle glycogen concentrations were significantly greater in swam versus non-swam trout in all treatment groups. Therefore, dietary SeMet exposure caused impaired swimming performance and metabolic alterations in both juvenile fathead minnow and juvenile rainbow trout. Species differences were apparent, especially in the patterns of altered energy status between swam and non-swam fish exposed to Se. Overall, the pathophysiological implications of these sublethal effects are unclear, but suggest that dietary SeMet exposure may negatively influence juvenile fish survivability in natural habitats.

Background: Strength is considered an important part in swimming and is usually included in training programs for swimmers. However, studies assessing the relationship between muscle strength, muscle endurance and swim performance are not many and have showed different results. Aim: The aim of this study was to assess the correlation between bench press, pull-up and 400 meter freestyle swim performance in elite swimmers. Method: The subjects (n=15, age 16-20) performed a one repetition maximum (1RM) bench press test to measure maximal muscle strength and to measure muscle endurance the subjects performed as many pull-up repetitions as possible during 30 seconds. A velocity four (V4) speed test was performed to assess swim performance by measuring time over covered distance and blood lactate levels. Results: The results of this study showed a moderate correlation (r=-0.54) between one repetition maximum in bench press and 400 meter freestyle swim performance. It showed a strong correlation (r=-0.63) between number of pull-ups repetitions during 30 seconds and 400 meter freestyle swim performance. Conclusion: These results suggest that upper body strength contributes to swim performance over 400 meter. The stronger correlation between pull-ups and swimming may indicate that muscle endurance of m. latissimus dorsi and the back muscles may be important to incorporate in a training program since it has shown to have a strong correlation with swim performance at 400 meters. / Bakgrund: Styrka anses vara en viktig del i simning och är ofta inkluderat i träningsprogram för simmare. Dock har endast ett mindre antal studier undersökt relationen mellan muskelstyrka, muskel uthållighet och simprestation och de som har gjort det visar olika resultat. Syfte: Syftet med denna studie var att utvärdera korrelationen mellan bänkpress, pull-ups och 400m simprestation hos elitsimmare. Metod: Deltagarna (n=15, ålder 16-20) utförde ett en repetition maximum (1RM) i bänkpress för att mäta maximal muskel styrka och för att mäta muskeluthållighet utförde deltagarna så många pull-ups repetitioner som möjligt under 30 sekunder. Ett velocity four (V4) hastighets test utfördes för att utvärdera simprestation genom att mäta tid över simmad distans och blod laktat värden. Resultat: Resultatet i denna studie visade på en moderat korrelation (r=-0,54) mellan en repetition maximum i bänkpress och 400 meter fristil simprestation. Den visade på en stark korrelation (r=-0,63) mellan antalet pull-ups repetitioner under 30 sekunder och 400 meter fristil simprestation. Konklusion: Dessa resultat tyder på att överkroppsstyrka bidrar till simprestation över 400 meter. Den starkare korrelationen mellan pull-ups och simning kan indikera att muskeluthållighet hos m. latisimus dorsi och ryggmusklerna kan vara viktigt att lägga in i ett träningsprogram då det visat på en stark korrelation till simprestation på distansen 400 meter.

Research in the multidisciplinary science of ecotoxicology is crucial to assess injuries to ecosystem resources from chemical spills or other stressors used to support environmental decision-making. Established guidelines recommend the use of non-standard native species in toxicity investigations. This work focused on the use of native species for aquatic toxicity assessment to make more relevant conclusions on the potential for adverse biological effects to occur as a result to single chemical exposures or exposures to a complex mixture like oil. We apply these studies to investigate petroleum product impacts from the Deepwater Horizon incident and concerns for metal toxicity in estuarine environments using a new model organism. Data generated from comprehensive toxicity testing programs were used in the first probabilistic risk assessment of Deepwater Horizon oil toxicity highlighting a lack of appropriate data and representative phyla. Novel toxicity study methods and a stress-response index were developed and demonstrated sensitivity and success in using the starlet anemone in ecotoxicology studies. Swim performance was used as new method to investigate sublethal indicators of stress resulting in varied responses from sheepshead minnows and Florida pompano. These studies further our ability for better laboratory-to-field extrapolation and for decision-making. The use of native species and complex mixtures like oil presented novel challenges in conducting aquatic toxicity studies. Special emphasis is placed on the necessity to understand the appropriate laboratory conditions for native species not typically held in the laboratory and maintaining study parameters to obtain quality data for more accurate interpretation and replication.