Rainbow trout are an important salmonid species whose poor utilization of dietary carbohydrates spurred research investigating molecular and physiological components of its glucoregulation. Among the environmental factors described to exert robust changes in glucose metabolism in rainbow trout, nutrition and social stress are among the most studied: Diets exceeding 20% of carbohydrates and chronic social stress induce hyperglycemia in adult and juvenile rainbow trout, respectively. Common to both responses is a contribution of hepatic de novo gluconeogenesis, which has been described to evade repression in response to high dietary carbohydrate content and to be stimulated in subordinate rainbow trout. Compared to previous studies investigating the regulation of hepatic gluconeogenesis at the molecular level, the recent publication of the annotated rainbow trout genome has opened novel possibilities to investigate paralogue-specific and posttranscriptional regulation of gluconeogenesis. In this thesis, I identify and describe the regulation of the novel phosphoenolpyruvate carboxykinase paralogue pck2b in rainbow trout and identify specific miRNA candidates predicted to contribute to gene paralogue-specific regulation of gluconeogenesis in nutritional and social contexts using small RNA next generation sequencing, real-time RT-PCR and in silico target prediction approaches. In nutritional and social status experiments, in silico predicted targets of differentially expressed hepatic miRNAs are enriched for gluconeogenesis regulation, suggesting a posttranscriptional component in regulating gluconeogenic transcript abundance. Differentially expressed hepatic miRNAs in both experiments comprise evolutionarily conserved and teleost-specific miRNAs, and are indicative of both environmental factor-specific and common regulation of gluconeogenesis transcripts in rainbow trout liver. Together this work provides novel comparative insight into hepatic miRNA-dependent glucoregulation and identifies several specific candidate miRNAs for future functional validation in hepatic glucoregulation in rainbow trout.

As all of Sweden's hydropower is to be re-examined within a 20-year period, methods are needed to carry out ecological investigations of dammed waterways. The first aim of this thesis is to evaluate whether methods for salmon and trout habitat mapping take all relevant indicators into account. In addition, the report aims to investigate which factors affect the results of habitat mapping based on hydraulic simulation and to investigate whether this method can be made more efficient through the use of simpler models, drone images and calculations. The work began with a literature study. A model was then built over a dammed stretch where mapping through hydraulic simulation was carried out. A mapping was then carried out on another stretch of stream based on a simpler model, drone images and shadow calculations, in parallel with a field mapping. The results of the literature study showed that the mapping methods capture the physical indicators well and indirectly link to certain chemical and ecological indicators. The method could be improved by including the water's nitrogen content and pH in the assessment.Important factors in habitat estimation with hydraulic simulation are the flow and the accuracy of the terrain model, as well as how the result is produced. The result from mapping with a simpler hydraulic model showed large deviations from the results obtained in the field, with respect above all to depth and width. Drone imagery for substrate assessment works well in shallow and clear water bodies. Shadow calculations based on how they were applied in this work to habitat mapping have not given satisfactory results, why the method needs to be developed. / Då all Sveriges vattenkraft ska omprövas inom en 20-årsperiod behövs metoder för att genomföra ekologiska utredningar av uppdämda vattendrag. Det första syftet med detta examensarbete är att utvärdera om metoder för lax- och öringhabitatkartering tar hänsyn till alla relevanta indikatorer. Därutöver syftar rapporten till att undersöka vilka faktorer som påverkar resultatet vid habitatkartering utifrån hydraulisk simulering och att undersöka om denna metod kan effektiviseras genom användning av enklare modeller, drönarbilder och beräkningar. Arbetet inleddes med en litteraturstudie. Därpå byggdes en modell upp över en indämd sträcka där kartering genom hydraulisk simulering genomfördes. En kartering genomfördes sedan på en annan strömsträcka utifrån en enklare modell, drönarbilder och skuggberäkningar, parallellt med en fältkartering. Litteraturstudiens resultat visade på att karteringsmetoderna väl fångar upp de fysikaliska indikatorerna och indirekt kopplar till vissa kemiska och ekologiska indikatorer. Metoden skulle kunna förbättras genom att ta in vattnets kvävehalt och pH i bedömningen. Viktiga faktorer vid habitatskattning med hydraulisk simulering är flödet och terrängmodellens noggrannhet, samt klassningen för vad som anses som goda habitat. Resultatet från kartering med en enklare hydraulisk modell visar på stora avvikelser mot resultaten inhämtade i fält, med avseende på framför allt djup och bredd. Drönarbilder för substratbedömning fungerar väl vid grunda och klara vattendrag. Skuggberäkningar utifrån hur de i detta arbete applicerats på habitatkartering har inte gett tillfredställande resultat, varför metoden behöver utvecklas.

The aquaculture industry has experienced a great expansion in recent years. Along with this growth, increased regulatory attention has been directed towards aquacultural effluents. The problem with the majority of these discharges is the solids and nutrient spikes that occur during times of high farm activity. Several studies have proven that these discharges have the potential to adversely affect downstream water quality. Although several treatment options are currently in use, the use of Best Management Practices (BMPs)has been recommended in recent years to improve the quality of these discharges. The implementation of one of these BMPs, the use of a high energy feed, was the focus of this study. In two separate experiments at trout raising facilities, the effluents of basins receiving a high energy feed were compared to similar basins receiving a standard trout grower feed. The water quality parameters of main concern were total suspended solids, total Kjeldahl nitrogen (TKN) and total ammonia nitrogen (TAN). The results of these studies showed that the effluents of basins receiving a high energy feed generally contained significantly lower concentrations of TSS, but higher amounts of TKN than those receiving a standard grower feed. / Master of Science

For a sexually reproducing species, the two major decisions facing all individuals are when and with whom to reproduce. When scaled to the population level, the outcome from all individual decisions determines reproductive variance, and age-class contribution to population growth rate. Both of these attributes determine a population‟s effective size (Ne), which is directly correlated with its fitness, persistence probability, and adaptability. The questions of when and with whom to reproduce, and their subsequent effects on Ne and age-at-maturity were assessed for wild brook trout (Salvelinus fontinalis) populations. Mating pairs were significantly size-assortative, with individual length accounting for 37% of the variation. This pattern of size assortative mate choice resulted in a reproductive strategy closer to monogamy than polygamy. Of all reproducing adults (n=157), 80% (n=126) produced only one full-sibling family, and only 6% (n= 9) contributed to more than two full-sibling families. The number of families and offspring contributed increased with length for both males and females. Comparison of the effective population size estimate to the adult census size (Nc) estimate returned an Ne:Nc ratio of 0.49 averaged over both populations. This value is nearly five times greater than the average reported across 165 (0.14) and 102 (0.10) different species. Age-at-maturity ranged from 0 to 2 years, with the proportion of age-0 and age-1 individuals maturing in a given year dependent upon growth opportunities determined primarily by environmental conditions. Mature fish were significantly larger than immature fish within an age-class, however, survival rates of mature and immature fish were similar. Furthermore, parental length did not influence offspring survival. These data suggest that the cost of early maturation is instead manifested through a reduction in egg number for females, and a reduced ability to acquire mates for males, both determined by an individual‟s size. Indeed, fecundity predicted by mean length of immature and mature fish within an age-class would result in mature fish producing an average of 38% (age-0) and 33% (age-1) more eggs than immature fish. These findings are discussed in the context of population persistence given the trend of increasing habitat fragmentation and looming climate change.

Ammonia excretion from the freshwater fish gill is thought to occur mainly via passive diffusion of NH3 aided by a favourable plasma-to-water ammonia gradient sustained by a pH gradient formed by an acidified gill boundary layer. Rhesus (Rh) proteins are the newest members of the ammonia transporter superfamily. In this thesis research, ten rainbow trout Rh cDNA sequences were cloned and characterized. Rhcg2 mRNA and H+-ATPase mRNA and activity levels were upregulated in the trout gill pavement cells in response to experimentally elevated plasma ammonia, concurrent with enhanced ammonia excretion. Controversially, Rh proteins are thought to transport C02. However, Rh mRNA levels in most tissues of hypercapnia-exposed trout remained stable suggesting that trout Rh proteins likely do not conduct C02. Xenopus oocytes expressing trout Rh proteins facilitated the bi-directional transport of methylamine, an ammonia analogue. Methylamine transport was inhibited by ammonia and sensitive to a pH gradient and the concentration of the protonated species. Use of the scanning ion electrode technique (SIET) indicated that trout Rh proteins have an ammonia affinity within the physiological range, which is greater than that for methylamine, and they transport ammonia more rapidly than methylamine. A model of ammonia excretion in the trout gill pavement cell is proposed wherein ammonia enters via basolateral Rhbg and exits via apical Rhcg2, binding to these channels as NH4+ but transiting as NH3. In the gill boundary layer, NH3 combines with an H+ ion released from H+-ATPase and/or Na+/H+ exchange, forming NH4+. As low-affinity, high-capacity ammonia transporters, Rh proteins in the trout gill would exploit the favourable pH gradient formed by the acidic boundary layer to facilitate rapid ammonia efflux when plasma ammonia levels are elevated. Basal plasma ammonia levels are likely maintained by simple passive NH3 diffusion with a smaller role for Rh proteins under these conditions. / Thesis / Doctor of Philosophy (PhD)

Over the past decade, research on microplastic pollution has gained significant attention. Research regarding microplastic occurrence in freshwater fish, however is still scarce. While possible pathways have been investigated, passive transfer via ingestion of prey, and possible bioaccumulation in different organs remains relatively unstudied. The scope of the work presented here was to examine microplastic occurrence in brown trout (Salmo trutta) and its main prey European smelt (Osmerus eperlanus) from Lake Vänern, Sweden. Further, my aim was to investigate for microplastics different organs such as stomach, liver, heart and intestine. Brown trout were collected by sport fishermen at sport fishing contests in Lake Vänern. All dissected organs were treated with hydrogen peroxide (H2O2) and particles were analysed and identified using Fourier transform infrared spectroscopy (FTIR). Microplastics were found in 94% of brown trout with 43% coming from the intestine, 41% from the stomach and 16% from the gastrointestinal tract of smelt. There was a significant difference in microplastic abundance between organs. No microplastics were fund in the liver or heart of brown trout. Fibres were the most abundant shape (95%) and black the most occurring colour (44%). The most abundant polymer types were neoprene, chlorosulfonated polyethylene and hydrogenated nitrile rubber and the smallest analysed particle was 100 m while the largest was 4.9 mm. In conclusion, my study confirmed the presence of microplastics in brown trout and its main prey from Lake Vänern, Sweden. Future research should focus on prey fish and different organs to give a better understanding of trophic transfer within the aquatic food web, and its possible bioaccumulation. / Under det senaste decenniet har forskningen om mikroplastföroreningar fått stor uppmärksamhet, men det finns fortfarande få undersökningar om mikroplastens förekomst i sötvattensfisk. Även om möjliga vägar har undersökts, är forskning på passiv överföring via intag av bytesdjur och eventuell bioackumulering i olika organ fortfarande relativt outforskat. Syftet med det arbete som presenteras här var att undersöka förekomsten av mikroplaster i öring (Salmo trutta) och dess huvudsakliga bytesdjur europeisk nors (Osmerus eperlanus) från Vänern, Sverige. Vidare var mitt mål att undersöka om det fanns mikroplaster i olika organ som mage, lever, hjärta och tarm. Öring samlades in av sportfiskare vid olika sportfisketävlingar i Vänern. Alla dissekerade organ behandlades med väteperoxid (H2O2) och partiklar analyserades och identifierades med hjälp av Fourier transform infraröd spektroskopi (FTIR). Mikroplaster hittades i 94 % av öringarna, där 43% kom från tarmen, 41% från magsäcken och 16% från mag- och tarmkanalen hos nors. Det fanns en signifikant skillnad i mikroplastmängden mellan organen. Inga mikroplaster hittades i lever eller hjärta hos öring. Fibrer var den vanligaste formen (95%) och svart den vanligaste färgen (44%). De vanligaste polymertyperna var neopren, klorsulfonerad polyeten och hydrerat nitrilgummi. Den minsta analyserade partikeln var 100 m medan den största var 4,9 mm. Sammanfattningsvis bekräftar min studie förekomsten av mikroplaster i öring och dess huvudsakliga föda från Vänern, Sverige. Framtida forskning bör fokusera på bytesfiskar och olika organ för att ge en bättre förståelse för trofisk överföring inom den akvatiska näringsväven, såsom möjlig bioackumulering.

No description available.

No description available.

The introduction of nonnative salmonids into Southern Appalachia may pose a threat to resident salamander populations. In recent years, the stocking and encroachment of rainbow trout (Oncorhynchus mykiss) into headwaters where the black-bellied salamander (Desmognathus quadramaculatus) and brook trout (Salvelinus fontinalis) naturally coexist has raised concerns. In aquatic prey, predator-avoidance responses are primarily influenced through the detection of chemical cues released from predators. The objective of this study was to determine how co-occurrence with a predator influences black-bellied salamander predator recognition behavior. To evaluate this, salamander activity metrics (general activity, number of movements, and latency to move) were recorded before and after exposure to either native trout predator cue (brook), introduced trout predator cue (rainbow), or conditioned tap water (control). Larvae were collected from different streams based on their trout predator assemblage with larvae coming from brook, rainbow, rainbow/brook, and no trout stream reaches. Our results show that larvae that co-occur with trout reduced their activity when exposed to brook trout predator cue, but their response to rainbow trout predator cue depended on their previous co-occurrence. Larvae from areas with only brook trout exhibited a weak predator-avoidance when exposed to rainbow trout predator cue. A follow-up test to determine the influence of alarm cue on predator response in these larvae indicated that the alarm cue enhanced the response to the rainbow trout predator.

Vattenkraftens ska förses med moderna miljövillkor i linje med miljöbalken. Ett av underlagen som föreslås vara nödvändigt inför prövningen är kännedom var det finns strömmande vatten och olika typer av habitat, något som inte finns i alla avrinningsområden. Arbetets syfte var därför att testa och utvärdera metoder som med begränsat underlag kan användas för att identifiera lax- och öringshabitat samt utreda sträckornas habitatskvaliteten.  För att genomföra detta genomfördes först en lutningsanalys där vattendragets strömsträckor identifierades genom att utifrån lantmäteriets höjdmodell, bestämma lutningen i vattendraget. Därefter bestämdes beskuggningsgraden vid strömsträckorna genom att studera flygbilder följt av parametrarna vattenhastighet, bredd och djup beräknades med MSB:s hydrauliska modell. På detta applicerades trout habitat score och laxhabitatklass, två bedömningssystem som används för att kvalitetsbestämma habitat utifrån fiskens habitatspreferenser för ovannämnda parametrar. Den predikterade habitatskvaliteten validerades sedan mot redan kända habitat som karterats i fält då vattendraget biotopkarterades.  Med lutningsanalysen identifierades strömsträckor där samtliga kända habitat som karterats som bra eller mycket bra identifierades. Metoden fungerade således bra för att identifiera strömmande vatten. Det finns dock svagheter eftersom metoden inte nödvändigtvis säger något direkt om strömsträckornas habitatskvalitet, men tillsammans med andra metoder så som lokalkännedom kan borde den vara till nytta att på ett enkelt sätt få en bra bild över utbredningen av vattendragets strömsträckor. När habitatskvaliteten beräknades vid strömsträckorna underskattades i de flesta fall. Vad detta beror på går inte att svara på utan vidare undersökning, men det finns mycket som pekar på att det är till följd av att den hydrauliska modellens rumsliga skala samt kalibrering. Det finns således stora osäkerheter med att använda MSB:s hydrauliska modell i habitatkarteringssyfte. / Hydropower is vital for Sweden. Not only does it provide Sweden with around 40% of the annual electricity production and supply the electric grid with system services, but the energy is also to be concerned as renewable with no greenhouse gas emissions. However, the hydropower plants and its dams create environmental problems for the aquatic life in the lake and streams. Moreover, little to no measures have been implemented as most powerplants come from a time where the concern and requirements for environmental mitigation measures were considered. Sweden’s hydropower is therefore to apply for new water permits in line with the Swedish environmental code, likely to result in many powerplants having to implement mitigation measures to lower their impact on the aquatic life. In this work, data on river habitats must compiled, however, the extent to which this data exists varies between different river basins. In river basins where the level of this kind of knowledge is low there is a need for cost-effective ways to investigate this matter.  The aim of the thesis was to test and evaluate methods that can be used to identify in stream habitats for trout and salmon parr and assess the quality of these habitats using data which is highly available for many river basins.  First a slope analysis was conducted in GIS, to identify rapids in the study area. The method is based on calculating the average slope along the river using the national terrain model. Once rapids were identified, aerial footage was studied to determine the rate of shadow cast on the watercourse and a free to use hydraulic model was used to calculate water velocity, depth, and top width at the rapid locations. Later, the above-mentioned parameters were combined using two methods, trout habitat score and salmon habitat class, to rate the rapids’ functionality as habitat for salmon and trout parr. Finally, the habitat location and quality of the identified rapids were validated against already known habitats, mapped with conventional habitat mapping methods.  Using the slope analysis, all known habitats were identified. However, there were a few uncertainties as several river stretches, not mapped as habitat, also were identified. These wrongly identified rapids were for the most part to be regarded as moderately flat and could be excluded using aerial photographs. When it comes to the predicted habitat quality, it can be concluded that it generally was underestimated when compared to the habitat quality from the habitat mapping. The reasons for this were not fully investigated in this thesis, however much points towards weaknesses related to the hydraulic model as it primarily was hydraulic parameters such as depth and top width that was underestimated.  The thesis conclude that the slope analysis is a strong tool when it comes to locating in stream habitats using sparse data and has good potential as a screening tool, but one must be aware of the method’s short comings. The hydraulic model on the other hand, shouldn’t be used in its original form to investigate habitat quality.