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Hedberg, Nils. "Sea cages, seaweeds and seascapes : Causes and consequences of spatial links between aquaculture and ecosystems." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-141009.
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Aquaculture is of growing importance in the global seafood production. The environmental impact of aquaculture will largely depend on the type of environment in which the aquaculture system is placed. Sometimes, due to the abiotic or biotic conditions of the seascape, certain aquaculture systems tend to be placed within or near specific ecosystems, a phenomenon that in this thesis is referred to as aquaculture system - ecosystem links. The exposed ecosystems can be more or less sensitive to the system specific impacts. Some links are known to be widespread and especially hazardous for the subjected ecosystem such as the one between the shrimp aquaculture and the mangrove forest ecosystem. The aim of this thesis was to identify and investigate causes and consequences of other spatial links between aquaculture and ecosystems in the tropical seascape. Two different aquaculture system - ecosystem links were identified by using high resolution satellite maps and coastal habitat maps; the link between sea cage aquaculture and coral reefs, and the one between seaweed farms and seagrass beds. This was followed by interviews with the sea cage- and seaweed farmers to find the drivers behind the farm site selection. Many seaweed farmers actively choose to establish their farms on sea grass beds but sea cage farmers did not consider coral reefs when choosing location for their farms. The investigated environmental consequences of the spatial link between sea cage aquaculture and coral reefs were considerable both on the local coral reef structure, and coral associated bacterial community. Furthermore, coral reef associated fish are used as seedlings and feed on the farms, which likely alter the coral food web and lower the ecosystem resilience. Unregulated use of last resort antibiotics in both fish- and lobster farms were also found to be a wide spread practice within the sea cage aquaculture system, suggesting a high risk for development of antibiotic resistant bacteria. The effects of seaweed farms on seagrass beds were not studied in this thesis but have earlier been shown to be rather substantial within the borders of the farm but less so outside the farm. Further, a nomenclature is presented to facilitate the discussion about production system - ecosystem links, which may also be used to be able to incorporate the landscape level within eco-certifying schemes or environmental risk assessments. Finally - increased awareness of the mechanisms that link specific aquaculture to specific habitats, would improve management practices and increase sustainability of an important and still growing food producing sector - the marine aquaculture.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.
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Barkerud, Rickard. "Welfare Evaluation of Stunning Practices for Farmed Fish in the European Union." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-107042.
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An optimal method for stunning animals before slaughter should result in instantaneous and irreversible insensibility. Today, there are various stunning and slaughter practices used around the world for farmed fish. With aquaculture being a growing food sector, the welfare of the animals used has become increasingly important in the consciousness of consumers, researchers and regulatory bodies. With growing research into the subject matter, an overview to summarize and examine how these practices impact on the welfare of the fish, and how well they conform to animal welfare legislation, is warranted to minimize the suffering of farmed fish. Stunning practices used in aquaculture include methods such as electrical and percussive stunning, carbon dioxide and asphyxiation. Each with its own level of effectiveness in terms of how fast the method results in loss of consciousness, whether or not the effect is reversible and how the welfare of the fish is affected as determined by behavioural and physiological stress responses. It was concluded that there is no unambiguous answer as to which stunning method is optimal in regard to animal welfare in modern day aquaculture. The optimal method for a given facility is influenced by factors like practicalities relating to each individual method as well as legislation on EU and national level. Suggestions were made for future research.
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Frank, Jakob, and Tom Hjälmefjord. "Gains N Greens." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42870.
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At present, it is focused either on aquaculture or agriculture. Those who focus on aquaculture or Recirculating Aquaponics System (RAS) receive a by-product of ammonia, which is then cleaned and the water either goes back to the fish or it is not cleaned at all and as they do in the salmon farms for example they let it sink to the bottom which creates eutrophication and major problems among the marine. Those who focus on agriculture use colossal amounts of land and outdoor areas for cultivation. Most of them use chicken manure and huge amounts of pesticides for the plants to be optimal. Another alternative is that you can use aquaponics, which is a kind of ecosystem where fish and plants live and thrive on each other's residual products. The fish produce ammonia in the fish tank which eventually makes the water uninhabitable and instead of having a cleaning pump in the fish tank, the water is sent to the cultivation bed where the plants pick up the nutrients and clean the water in turn so that the water can be pumped back to the fish tank. This system makes it possible to produce both fish and plants in an optimized and safe system. Aquaponics is advantageous in that it utilizes the by-product of the fish and gives it to the plants. Where ammonia is the fish’s residual product that turns into nitrite and then to nitrate and it is precisely nitrate that the plants use as nutrition, in turn, they purify the water that goes back into the fish tanks, which gives a closed cycle. At present, aquaponics has not been able to impact on a large scale more than in a few places, partly because there is ignorance of how it works and partly because it requires technical knowledge of how to build a functioning system together. The project goal that we strive for is to get a PlugNPlay solution that enables people who want to invest in aquaponics, but do not have the technical knowledge to compile a functioning optimal system. The project group will also compare different farming methods and make measurements on which medium is the best to grow in, but also what kind of food that works to grow in an efficient way.I dagsläget fokuseras det antingen på vattenbruk eller på jordbruk. De som fokuserar på vattenbruk eller Recirkulerande Akvaponiska System (RAS) får en biprodukt bestående av ammoniak, som sedan rengörs och vattnet går antingen tillbaka till fiskarna eller så rengörs det inte alls och som de gör i till exempel laxodlingarna, de låter det sjunka till bottnen vilket skapar övergödning och stora problem bland det marina. De som fokuserar på jordbruk använder kolossala mängder av jord och ytor utomhus för att kunna odla. De flesta använder sig av hönsgödsel och enorma mängder bekämpningsmedel för att plantorna ska bli optimala. Ett annat alternativ är att man kan använda sig av akvaponik som är ett sorts ekosystem där fiskar och växter lever och frodas på varandras restprodukter. Fiskarna producerar ammoniak i fisktanken som gör så att vattnet till slut blir obeboeligt och istället för att ha en rengöringspump i fisktanken så skickas vattnet över till odlingsbädden där växterna plockar upp näringen och rengör vattnet i sin tur så att vattnet sedan kan pumpas tillbaka till fisktanken. Detta system gör det möjligt att producera både fisk och växter i ett optimerat och säkert system. Akvaponik är fördelaktigt i den mån att den utnyttjar biprodukten ifrån fiskarna och ger denna till växterna. Där ammoniak är fiskens restprodukt som blir till nitrit och sedan till nitrat och det är just nitrat som växterna använder som näring, i sin tur så renar de vattnet som går tillbaka in till fisktankarna vilket ger ett slutet kretslopp. Akvaponiken har i dagsläget inte slagit igenom storskaligt mer än på ett fåtal platser, dels för att det finns okunskap om hur det fungerar dels för att det krävs teknisk kunskap om hur man bygger ihop ett fungerande system. Projektmålet som vi strävar efter är att få till en PlugNPlay lösning som gör det möjligt för människor som vill satsa på akvaponik men inte har den tekniska kunskapen att sammanställa ett fungerande optimalt system. Projektgruppen kommer även att jämföra olika odlingssätt och göra mätningar på vilket medium som är bäst att odla i men även vilken sorts mat som fungerar att odla på ett effektivt sätt.
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Lindbladh, Emma, and Johanna Eriksson. "Phenotypic correlates of spawning migration behaviour for roach (Rutilus rutilus) and ide (Leuciscus idus) in the stream Oknebäcken, Sweden." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-98343.
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Migration occurs among many animal species for the purpose of, among other things, finding food or to reproduce. Spawning migration is a form of migration that occurs among many fish species where they move to another site for reproduction. The movement can be obstructed by migration barriers like road culverts. Barriers to migration pose one of the greatest threats to biodiversity and ecosystem functions in freshwater. They impair the connectivity of watercourses and may prevent fish from improving reproductive success or completing their life histories altogether. There are both benefits and costs with migration, benefits such as increased survival for the adults and offspring, and costs such as increased energy consumption and increased mortality. The costs are often dependent on the morphological traits of the individual, like body shape and size. In this study, the spawning migration of two species of fish of the family Cyprinidae, ide (Leuciscus idus) and roach (Rutilus rutilus) was investigated. Few studies have been made on ide or on roach compared to other cyprinids and salmonids. This study might therefore enhance the overall knowledge of these two species. The overall aims of this project are to study and compare phenotypic correlates of spawning migration behaviour of ide and roach. The field studies were performed in Oknebäcken, Mönsterås (SE632310-152985), Sweden in March and April 2020. To describe the watercourse and define the location and characteristics of different potential migration barriers, a simplified biotope mapping method was used. The fish were caught in a hoop net and then measured, weighted, sexed, and injected with passive integrated transponder using the bevel down method. In order to register in stream movement of fish, reading stations with antennas were placed, at two locations upstream from the marking station and one downstream at the estuary. The sex ratio differed from the expected 1:1 with a majority of females for both species. This might be a result of fluctuations in survival of spawn coupled with different age-at-maturity between sexes. We found that individuals that arrived early to the stream were larger for both study species, as other studies also reported. Also, male ide was both larger and arrived before female ide. There might be an energy cost associated with early arrival to the stream and therefore, larger individuals arrive first. For roach, there was no difference in arrival time between the sexes although female roach were larger. There was no difference in the time spent in the stream between the species. For ide, females stayed for a longer period of time in the stream than males. However, the opposite was true for roach. This may be because male roach might benefit from more fertilization events when staying longer. There might therefore be a trade-off between the energy cost in staying in the stream and the increased fitness advantage in fertilization events. We found no correlation between any of the morphological traits and migration distance. However, since very few individuals were registered at the upstream reading stations, there might be an effect of migration barriers on the spawning migration. The mortality after spawning was higher for roach than for ide. For ide, a larger proportion of females than males died. For roach, individuals that arrived early was classified as alive to a greater extent than those who arrived late. Both similarities and differences between the species were discovered in this study which concludes that even closely related species might differ substantially from each other.
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Murray, David S. "The role of physical structure and micronutrient provisioning in determining egg quality and performance in fish." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3563/.
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This thesis examined novel and previously utilised parameters of egg quality to determine and define reproductive success in farmed and wild salmonids. The effect of holding environment and inter-female variation on salmonid egg quality was also examined. Furthermore, two nutritional feed trials were undertaken to investigate whether organic Se, supplemented into salmonids broodstock diets, was vertically transferred to their eggs and what affect this dietary supplementation had on egg quality. Finally, the possibility that morphological and biochemical adaptations are present on the chorion of eggs from European whitefish (Coregonus lavaretus) was investigated in a resident Scottish population. Chapter 2 examined methods to determine egg quality using eggs from a single population of brown trout (Salmo trutta). Egg survival, provided a biologically relevant definition for egg quality, which was used throughout this study to assess the importance of selected egg quality parameters. Based on a review of the literature and the relationship between parameters of egg quality and egg survival rates, three determinants of egg quality were chosen for further examination. These were chorion breaking strength, elemental concentrations within the egg and the protein profile of the chorion. Brown trout broodstock from a single population were separated prior to spawning and exposed to two different holding units, ‘Ae system’ or ‘S.C.E.N.E. system’ at two sites. Eggs were stripped from females and 13 determinants of egg quality collected, analysed individually, combined by principle components analysis into an integrated egg quality score which was validated against egg survival. The multivariate egg quality score differed significantly between fish held in the Ae and S.C.E.N.E. systems. Egg survival, chorion breaking strength and Se chorion concentrations were higher in eggs produced by broodstock held in the S.C.E.N.E. system compared to those in the Ae system. Alternatively, chorion concentrations of P and K were higher in eggs from fish held in the raceway system. This data highlights the complex interactions between the holding environment and pre-ovulating fish and resultant egg quality. The variation in egg survival in individual Atlantic salmon (Salmo salar) reared in the same environment was assessed and used to examine the suitability of chorion measurements as parameters of egg quality. There was a significant difference in the egg survival rates between individual salmon. Results also show that there was also variation in egg survival, chorion breaking strength, chorion elemental concentrations and chorion protein concentrations and profiles between individual Atlantic salmon. Subsequent analysis of the data showed that there was no difference in these egg quality parameters between high and low egg survival rates. Furthermore, there was no correlation between egg survival and the chorion quality parameters recorded during this study. The results show that individual variation between fish is an important factor affecting egg quality. Broodstock Atlantic salmon were fed a standard commercial diet, with or without the addition of a supplemented nutritional mix, which included 0.5mg/kg of Sel-plex (organic Se). The Se content of the eggs and livers of each fish were assessed as was egg survival rates and proteomic analysis of the egg chorion. Concentrations of Se in the eggs of the individuals fed the supplemented diet were significantly higher than those fed the non-supplemented diet. However, the egg survival rate was also significantly lower in the supplemented group of fish. The assessment of the chorion protein profile and its proteomic structure was inconclusive. These results support the hypothesis that dietary selenium is vertically transferred to immature eggs during oocyte development. The lack of a linear relationship between Se egg concentrations and egg survival suggests that the lower survival rates of eggs from broodstock fed the supplemented diet in this trial was due to another nutritional component of the diet rather than the Se. Selenium enriched eggs from Atlantic salmon fed a supplemented diet and eggs from conspecifics fed a non-supplemented diet were tested for their ability to resist infection by Saprolegnia under incubation conditions similar to those used by the aquaculture industry. There was no significant difference in the presence/absence of infection, infection rate or survival between eggs produced by Atlantic salmon fed the supplemented and non-supplemented diet. Therefore, it was concluded that supplementation of broodstock diet does not alter the resistance of eggs to Saprolegnia. The presence of adhesive mechanisms on the surface of European whitefish eggs was examined from a population found within Loch Eck, Scotland. European whitefish eggs remain non-adhesive in a solution chemically similar to ovarian fluid, but become adhesive seconds after contact with water. Examination of the ultrastructure of the chorion showed that the morphology altered significantly after contact with water with nodule-like protuberances attached to connective filaments on the surface, present in water hardened but not non-water hardened eggs. Biochemical analysis also showed the presence of Chain A, RNase ZF-3e in the chorion of water hardened but not non water hardened eggs. Histochemical staining of the chorion showed that the externa, but not the interna stained positively for the presence of glycoproteins. Egg adhesive mechanisms allow European whitefish eggs to remain in optimal spawning grounds where factors such as mechanical damage, predation, desiccation and hypoxia are minimised.
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Hamilton, Michael T. "Determining Spawning Occurrence and Reproductive Potential of Shenango River Lake Walleye." Connect to resource online, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1251895859.
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Maillard, Vincent M. "Characterization, Treatment, and Improvement of Aquacultural Effluents." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/30908.
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During the water quality and sludge characterization phase, average effluent quality over the course of a day was not found to be impaired during a 7-month sampling and monitoring study at the three trout farms. However, effluent quality was found to change significantly during times of high farm activity (i.e. feeding, harvesting, cleaning, etc.). Normalized Total Suspended Solids (TSS) concentrations were found to be as high as 115 mg/l during harvesting and 63 mg/l during feeding. Solids characterization studies proved farm waste solids degrade over time and that their particle size distributions are a function of the feed size and activity of a certain raceway. Waste solids accumulation studies proved that the solids removal efficiency of farm sediment traps were very low, and after a certain period of time, they reached capacity due to particle scouring.
A pilot plant was constructed in the water and sludge treatability phase to prove a baffled settling scheme was sufficient to treat average and peak TSS concentrations during a normal workweek. The study found optimal TSS removals at detention times of 15-20 minutes, and overflow rates of 77.4 â 48.9 m3/m2·d. Given economic, spatial, and operational constraints, sedimentation was found to be the most feasible treatment technology for raceway-system trout farms.
Master of Science
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Gatonye, Margaret. "Social Inclusivity and Equitable Development: Women in Fisheries and Aquaculture in Rural Communities of Kenya." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1586540674871228.
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Klase, Gary L. "The Chinese liver fluke Clonorchis sinensis: an environmental investigation into a foodborne parasite." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366378549.
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Barton, Mark B. "Spatial and Temporal Patterns of Arctic Nearshore Fish Community and Food Web Structures." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3735.
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Climate change and increasing anthropogenic activities are causing rapid changes to environmental and ecological processes in the Arctic Ocean. To better understand these changes, scientists have increased research efforts in these regions, but to date the number of studies on Arctic nearshore habitats are lacking. My dissertation responds to the paucity of information and investigates patterns in Arctic nearshore fish communities and food webs to gain insight to how these ecosystems may shift as these changes continue. I used multivariate statistical analysis to examine patterns in community structure and composition to determine that Arctic nearshore fish communities are largely driven by prey availability, salinity and temperature; and that species that are more abundant in warmer conditions are likely to increase in abundance as climatic conditions in the Arctic continue to warm. I improved the ability to apply stable isotope methods to Arctic food web studies by determining more appropriate model parameters using a laboratory-based isotope study on a common Arctic nearshore fish, and discuss its potential as a biological monitor species. These new parameters are used to confirm that a shift in prey resource dependence occurs across the seasonal shift from ice-covered winter to open-water summer conditions. Changes in basal resource dependence also occur later in the season across a latitudinal gradient where a shift to dependence on allochtonous inputs from nearby rivers increased trophic diversity. Using isotopic niche space theory, it was determined that the Arctic nearshore has a diverse prey base but that niche spaces of Arctic warm-water and cold-water species do overlap, and if numbers of warm-water fish continue to increase it will likely increase competition for resources for potentially less-adaptable, well-established, cold-water forage fish. On the other hand, if pelagic productivity is expected to increase and support larger fish biomasses, then there will be more than enough resources for warm-water and cold-water species to coexist, thus creating a more diverse prey base for piscivores in the Arctic.
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Vestling, Veronika, and Viktoria Forsberg. "The livelihoods of female seaweed farmers : A study about women's experiences of old and new techniques of seaweed farming on Zanzibar, Tanzania." Thesis, Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Globala studier, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-40719.
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Seaweed has been hit hard by climate change around the world. The island of Zanzibar, which is the world’s third biggest exporter of seaweed, is one of the places where seaweed is affected. 80 percent of the seaweed farmers on Zanzibar are women who are directly affected by climate change since they are making a living from seaweed farming. New efforts to tackle the impact of climate change on seaweed has been made on Zanzibar through the SEA PoWer project which is a new technique of growing seaweed and enables twenty-four female seaweed farmers to grow in deep and cooler waters instead of the more traditional way which is in shallow waters. The aim of this study is to, from a livelihood perspective, examine women’s experiences and perceptions of the old versus the new techniques of farming seaweed on Zanzibar, Tanzania. The research questions for this study focus on finding out the women’s experiences and perceptions of the changes in the techniques in relation to opportunities for livelihoods through seaweed farming. Furthermore, this study investigates if women experience conflicts of interest with men regarding the use of ocean space. Semi-structured interviews with eleven women who have used the new technique of growing seaweed were conducted and the results was analyzed in the light of previous research, through the definitions of livelihood and gender, and the theoretical concept of feminist political ecology. The result has shown that all women experienced improvements in their livelihoods through the new technique of seaweed farming. One clear improvement was that there were no negative health effects when using the new technique. The study also found that there are no conflicts of interest between men and women regarding the use of ocean space when using the new technique of seaweed farming. The women had a positive view on the future and had high expectations, they had already noticed positive effects on their livelihoods in form of social, human, physical capital and health.
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Boyle, William Antonio. "Development of a computer vision fish biomass measurement procedure for use in aquaculture /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/5325.
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Singh, Sahdev. "Modeling thermal environment of a recirculating aquaculture system facility." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12302008-063343/.
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Selden, Justin D. "The Effect of Dredging on Fish Communities in Agricultural Streams in Crawford, Sandusky and Seneca Counties of Ohio." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372421206.
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Bélanger, Bernard. "Étude de certains aspects du développement larvaire chez le doré jaune (Stizostedion vitreum vitreum) /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1992. http://theses.uqac.ca.
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Filbrun, Jesse Everett. "An Ecological Approach to Feed Management in Fish Rearing Ponds." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366038927.
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Schloesser, Joshua Thomas. "Large river fish community sampling strategies and fish associations to engineered and natural river channel structures." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/888.
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Hill, Jenna D. "Validation of Antibodies Used to Study Hypoxia Inducible Factors in Two Species of Fundulus." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1636.
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Hypoxia inducible factors (HIFs) are transcription factors and the master regulators of oxygen-dependent gene expression in animals. The focus of this thesis is the distribution of HIF protein in tissues of the fish Fundulus heteroclitus and F. grandis, two widespread species that occur in naturally hypoxic waters. Polyclonal antibodies against HIF-1α, HIF-2α, and HIF-3α were tested on proteins made in vitro and on extracts made from several tissues of normoxic and hypoxic fish. Antibodies against HIF-1α and 3α bound specifically to full length protein made in vitro, and produced bands on western blots of nuclear extracts of near the expected molecular weights for these proteins. Hypoxic exposure did not markedly increase the intensity of these bands, and mass spectrometry failed to identify HIF-1α and 3α peptides in excised gel bands. Thus, further tests of antibody specificity are needed before the tissue distribution of HIF in these fish can be confidently assessed.
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McCulloch, Danielle. "PELAGIC FISH DIVERSITY AND DENSITY ON AND OFF RESTORED OYSTER REEF HABITAT." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5180.
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The heterogeneity provided by structured habitats is important in supporting diverse and dense fish communities. The biogenic reefs created by the native Eastern Oyster, Crassostrea virginica, were once the dominant structural habitat in Chesapeake Bay, and have since declined to less than 1% of historic estimates. Conflicting results on the effects of oyster reef restoration on pelagic fish assemblages make further investigation necessary. Incorporating multiple sampling strategies may help elucidate oyster reef habitat influence on fish assemblages. This study used multi-panel gillnets, hydroacoustic technology, and day-night sampling to describe pelagic fish assemblages on and off oyster reef habitat in the lower Piankatank River, VA. Data from oyster reef habitat, adjacent sandy-mud bottom habitat, and unstructured sandy habitat outside of a reef restoration area compared fish diversity, species composition, and density among habitat types. A multivariate analysis using day of the year, day or night, and habitat type as model terms found temporal factors explained variation in fish distribution more than habitat. Fish diversity varied significantly with day or night and habitat type. Diversity and density were significantly higher at night, demonstrating the necessity of nocturnal sampling in fish assemblage research. Results from this study conclude that fish assemblages were not significantly more diverse or denser on reef than non-reef habitat. We suggest that future work should concentrate on studying areas where oyster reef habitat comprises a larger proportion of the study area.
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LaMacchia, Brian A. (Brian Andrew). "Internet fish." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11049.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 98-102).
by Brian A. LaMacchia.
Ph.D.
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Al-Reasi, Hassan Ali. "Tracking mercury biomagnification in fish from the Gulf of Oman using stable isotopes (carbon-13carbon-12 and nitrogen-15nitrogen-14)." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26836.
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Attempts to use stable isotope carbon (delta13C) and nitrogen (delta15N) ratios to construct trophic positions and track mercury biomagnification in zooplankton and 13 fish species from a coastal food web of the Gulf of Oman illustrated some potential differences in this environment compared to the aquatic ecosystem of the northern hemisphere. Due to the large difference in delta13C values (3.4‰) between zooplankton planktivorous fish species (S. crumenophthalmus, S. longiceps and R. kanagurta), zooplankton would seem to not be the primary diet of these fish species as commonly described in literature.
Total mercury (T-Hg) concentrations of zooplankton were very low (range 0.010 to 0.037 mug·g-1, N = 27) with a mean methyl mercury (MeHg) of 0.001 mug·g-1 (range 1-19%, N = 5). The lowest T-Hg (0.003 mug·g-1) was found in planktivore (S. longiceps) and the highest was 0.760 mug·g -1 in predator shark (R. acutus) with average MeHg for all fish of 72% (range: 33-100%, N = 150). Using 15 N as indicator of trophic position, neither total mercury (T-Hg) nor methyl mercury (MeHg) were found to biomagnify. Regression slopes were 0.08 and 0.05 for T-Hg and MeHg respectively as a function of delta15 N. This indicates that biomagnification was lower in this tropical ocean compared to that found in freshwater and marine ecosystems of the arctic and temperate zones.
Methyl mercury levels in the fish species commonly consumed are low and intake calculations showed that individuals can safely consume fish.
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Schoonbee, Willem Lodewyk. "The qualitative and quantitative description of growth and condition of silver kob, A. inodorus." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1193.
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Brownell, Lindsay Kirlin. "One fish, two fish, lungfish, youfish : embracing traditional taxonomy in a molecular world." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92629.
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Thesis: S.M. in Science Writing, Massachusetts Institute of Technology, Department of Humanities, Graduate Program in Science Writing, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 23-24).
In today's increasingly digitized, data-driven world, the "old ways" of doing things, especially science, are quickly abandoned in favor of newer, ostensibly better methods. One such discipline is the ancient study of taxonomy, the discovery and organization of life on Earth. New techniques like DNA sequencing are allowing taxonomists to gain insight into the tangled web of relationships between species (among the Acanthomorph fish, for example). But is the newest, shiniest toy always the best? Are we in danger of losing vital information about the world if we abandon the thousands of years of cumulative human knowledge to gather dust in basements? This thesis explores the current crossroads at which taxonomy finds itself, and offers a solution to preserve the past while diving headlong into the future.
by Lindsay Kirlin Brownell.
S.M. in Science Writing
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Arunachalam, Subbiah, and Jayashree Balaji. "Fish Science Research in China: How does it Compare with Fish Research in India?" Jointly published by Akadémiai Kiadó, Budapest and Kluwer Academic Publishers, Dordrecht, 2001. http://hdl.handle.net/10150/105477.
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Fish and aquaculture research in the Peopleâ s Republic of China over the six years 1994-1999 has been mapped using data from six databases â three abstracting services and three citation indexes. The results are compared with fish science research in India. During the six years China has published 2035 papers (roughly 4.5 â 5% of the world output) and India 2454. More than 95% of Chinaâ s papers are journal articles, compared to 82.8% of Indian papers. About 78% of Chinaâ s journal paper output has appeared in 143 domestic journals compared to 70% from India in 113 Indian journals. Less than one-eighth of the journal articles published by Chinese researchers are published in journals indexed in SCI, compared to 30% of journal articles by Indian researchers. Less than a dozen papers from each of these countries have appeared in journals of impact factor
greater than 3.0. Fish research institutes and fishery colleges are the major contributors of the Chinese research output in this area. In India academic institutions are the leading contributors (61%), followed by central government institutions (>25%). Qingdao, Wuhan, Beijing and Shanghai are the cities and Shandong, Hubei and Fujian are the provinces contributing a large number of papers. As we do not have addresses of all authors in most of the papers, we are unable to estimate the extent of international collaboration. Although Chinaâ s research output and its
citation impact are less than those of India, Chinaâ s fish production and export earnings are far higher than those of India. Probably China is better at bridging the gap between knowhow (research) and do-how (technology and creation of employment and wealth). China is pretty strong in extension.
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King, Judy A. "Adaptation of Striped Bass to Sea Water Following Direct Transfer from Freshwater: Morphological, Biochemical, and Physiological Parameters." Digital Commons @ East Tennessee State University, 1987. https://dc.etsu.edu/etd/2932.
Full textAbstract:
There has been heightened interest in the biology of striped bass (Morone saxatilis) because of increased pollution in their native spawning grounds and because of their extensive use in landlocked sport fisheries. Their euryhalinity makes them an excellent species for osmoregulation studies. The objective of this research was to study the rate of adaptation of striped bass gills to sea water (3% salt) after direct transfer from freshwater using biochemical (ion transport enzyme levels), physiological (chloride efflux), and ultrastructural methods. Striped bass have specialized osmoregulatory cells located on the interlamellar and afferent surfaces of their gill filaments as shown by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). SEM studies show that apical pit (opening of one or more chloride cells) morphology changes during sea water adaptation, and the number of apical pits increases by 32.5% after two weeks in sea water. Chloride cell size and number, extent of basolateral tubular system, and number of mitochondria per chloride cell appear to increase upon adaptation to sea water. Sodium-potassium adenosine triphosphatase (Na,K-ATPase) activity is maximal on day 3 after transfer to sea water. Studies suggest that cortisol may act as a hormonal mediator for long term adaptation to sea water. The general morphology of both freshwater and sea water adapted fish gills were studied. Preliminary studies indicate that the osmium-dimethylsulfoxide-osmium method can be used to investigate intracellular structural changes in striped bass gills. Since the chloride cells are associated with the afferent surface of the filament, the blood supply to that area is also of great interest in osmoregulation studies. Studies of the gill vasculature using corrosion casting (i.e. filling blood vessels with plastic resins) and SEM indicate that the blood vessel distribution in the striped bass gill is similar to that of other euryhaline species with arterio-arterial, arterio-venous, and nutritive pathways. Blood flow may be controlled at a variety of places by sphincters, shunts and cellular contraction. Correlation of these biochemical, physiological and anatomical measurements will aid in the understanding of the process of adaptation to sea water. (Abstract shortened with permission of author.)
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Bolland, Jonathan David. "Factors affecting the dispersal of coarse fish." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:1366.
Full textAbstract:
Globally, freshwater fisheries are faced with numerous impacts that compromise fish populations. A knowledge and understanding of riverine fish movements are crucial for effective management and conservation of populations. However, there is a paucity of information about the spatial behaviour and ecology of wild and stocked cyprinids in floodplain rivers, especially under the influence of elevated flows. This study examined the factors affecting the lateral and longitudinal dispersal of juvenile and adult (wild and stocked) coarse fish in three lowland river catchments, namely the River Trent, the Yorkshire Ouse and the River Roding.A literature review was carried out to review the influence of floods on riverine ecosystem function and structure, and fish assemblage patterns. In unmodified lowland rivers, floods are characterized by lateral expansion onto floodplains resulting in high levels of habitat heterogeneity, essential for fish refuge, spawning, nursery and feeding. However, anthropogenic alterations to the flow regime and floodplain connectivity have had considerable detrimental impacts on fish populations. The main conclusion of the review was the need to restore and rehabilitate lowland rivers in an attempt to recover natural features or functionality. The effects of flood timing and magnitude were examined by sampling 0+ fish populations before, during and after floods in the Yorkshire Ouse, a constrained lowland river. Large numbers of eurytopic 0+ fishes were stranded on isolated floodplains when artificial levees ‘over-topped’ in summer (August). By contrast, backwaters provided refuge for high densities of 0+ eurytopic and rheophilic fishes. During floods, small fish were displaced or had lower survival. The results highlight the influence of flood timing on 0+ fish populations, the use of refuge areas and their importance of lowland river rehabilitation.In the River Trent, 0+ fish populations were sampled in the margins of the main river channel and in ten man-made floodplain waterbodies to evaluate the importance of variable connectivity between these habitats for rehabilitating the riverine-floodplain ecosystem. Fish assemblages compared favourably with studies on unmodified river reaches, i.e. succession of lotic-to-lentic habitat corresponded to a sequence of rheophilic-to-eurytopic-to-limnophilic fish species. Consequently it was concluded that the connection of man-made floodplain waterbodies to the river should incorporate variable, not just high, levels of hydrological connectivity into holistic riverine ecosystem management plans.Dual-Frequency Identification Sonar (DIDSON) was used to determine the influence of elevated flow on the lateral movements of adult fish between the Yorkshire Ouse and a marina (refuge habitat). Fish activity in the entrance was predominantly during daylight hours. Increased river flow resulted in significantly reduced fish movements, both towards and away from the marina, and fish presence in the entrance, except for larger fish (more than 30 cm) during the night. This study emphasised the importance of artificial floodplain waterbodies for adult cyprinid fish during winter months.The influence of environmental variation (flow and temperature) on movements of wild and stocked adult cyprinids is poorly understood, partially because of experimental difficulties. A laboratory study on PIT tagging individual juvenile cyprinids, identified that the method would be suitable for such investigations. In the River Roding, a combination of PIT and radio telemetry was used to compare habitat use, longitudinal movement (timing and direction), site fidelity and survival between wild populations and hatchery-reared fish. Wild cyprinids had high levels of ‘site fidelity’ but highly mobile individuals were present within the population, with movements positively correlated with temperature and flow. During elevated winter flows, wild fish occupied areas of reduced flow to reduce energy expenditure, but some fish performed exploratory movements. Movements of stocked fish were more frequent and longer than for wild fish, particularly just after release, possibly for exploratory purposes. Subsequently, movements of stocked fish were minimal, did not correlate with flow or temperature and the final distributions were more widely dispersed than found in wild fish. Importantly from a stocking perspective, stocked cyprinids had the behavioural and physiological ability to cope with elevated flows. However, differences in movements and habitat use between wild and stocked chub probably had consequences on survival.
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Filbert, Randall B. "Is Rainbow Trout Condition Influenced By Invertebrate-Drift Density?" DigitalCommons@USU, 1991. https://digitalcommons.usu.edu/etd/6494.
Full textAbstract:
Users of the Instream Flow Incremental Methodology CTFIM) commonly assume that there is a positive linear relationship between available habitat (WUA) and stream fish biomass. However, several studies have shown a lack cf correlation between WUA and biomass. Such poor relationships may occur if other factors limit fish abundance. Food availability is a potentially important factor limiting abundance of stream fishes and can affect blomass by influencing fish condition (individual weight). I collected rainbow trout (Oncorhynchus mykiss) exposed to different levels of invertebrate-drift density to determine if condition was greater where food was more abundant. I also examined whether size-selective predation and gut fullness varied with drift density.
Size-selective predation was not related to drift density. However, condition and gut fullness were both significantly correlated with drift density. Furthermore, changes in drift density appeared to have a stronger influence on small-trout condition than large-trout condition. The results of this study and others support the contention that the reliability of the IFIM might be improved if food availability were incorporated into models.
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Bjornsdottir, Kristin. "Detection and Control of Histamine-Producing Bacteria in Fish." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-03242009-101524/.
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Histamine (or scombroid) fish poisoning the most frequently reported illness associated with consumption of fish despite efforts of its control. The lack of adequate control measures and unreliable detection method for histamine-producing bacteria (HPB) can in part be responsible for the high incidence of the disease. The aim of the studies was to address these concerns. Available detection methods were compared and related to histamine-production. Next, a DNA probe based on the histidine decarboxylase (hdc) gene was developed and applied to colony lift hybridization for enumeration of HPB from fish. Finally, the used of phosphate as a control of HPB was examined. The results demonstrated that the potentiometric, and PCR detection methods accurately detected high-HPB but did not detect the low histamine producing isolates. Although, the culture-based Nivens method, detected low histamine-producing bacteria, it resulted in 38% false positive responses. A hdc-probe mix from four HPB detected all 73 high-histamine producing bacteria in DNA dot-blot hybridization. However, six low and seventy-three non-HPB were not detected. Application of the hdc-probe mix in colony-lift hybridization resulted in more accurate quantification of HPB compared to the commonly used Nivenâs method. Phosphate treatment of mahi-mahi samples significantly reduced histamine-production by increasing the surface pH of the fish muscle. The ability not only to detect but enumerate histamine-producing bacteria in fish is important for evaluating the potential risks and to develop adequate control strategies prior to formation of toxic levels of histamine.
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Song, Juha. "Multiscale materials design of natural exoskeletons : fish armor." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69670.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 261-282).
Biological materials have developed hierarchical and heterogeneous material nanostructures and microstructures to provide protection against various environmental threats that, in turn, provide bioinspired clues to man-made, protective material designs. In particular, designs of dermal fish armor are a tradeoff between protection and mobility. A comprehensive knowledge base of the materials and mechanical design principles of fish armor has broad applicability to the development of synthetic engineered protective/flexible materials. In this thesis, two fish armor model systems have been investigated by means of structure-property-function relationships, ultimately answering how the armor systems have been designed in response to their environmental threats. The first model system, Polypterus senegalus are descendants of ancient fish and their body is covered by a natural armor consisting of small bony scales. The quadlayered armor scales are composed of ganoine, dentin, isopedine and bone, to protect against predatory biting attacks. First of all, multilayer design principles of P. senegalus scales were understood with respect to penetration resistance by the multiscale experimental and computational study. The quad-layered scales exhibit mechanical gradient within and between material layers and have geometrically corrugated junctions with an undetectable gradation; all of which lead to effective penetration resistance including load-dependent effective material properties, circumferential surface cracking, plastic dissipation in the underlying dentin layer, stress redistribution around the interfaces with suppression of interfacial failure. Secondly, since the outmost ganoine is structurally anisotropic, the roles of anisotropy of ganoine in the entire system have been investigated by combining orientation-dependant indentation and mechanical modeling. The elastic-plastic anisotropy of the ganoine layer enhances the load-dependent penetration resistance of the multilayered armor compared with the isotropic ganoine layer mainly by (i) enhancing the transmission of stress and dissipation to the underlying dentin layer, (ii) lowering the ganoine/dentin interfacial stresses and hence reducing any propensity toward delamination, and (iii) providing discrete structural pathways for cracks to propagate normal to the surface for easy arrest by the underlying dentin layer. Inspired by P. senegalus scales, threat-protection interaction and structurefunction relationships among various layered armor systems have been investigated using parametric studies with finite element (FE) models. Geometry, microstructure and mechanical properties of a threat system significantly influence its ability to effectively penetrate into the armor system or to be defeated by the armor. Simultaneously, three structure parameters of multilayered armor designs are mainly considered: (i) the thickness of the outmost layer; (ii) the quad-layered vs. bilayer structure; and (iii) the sequence of the outer two layers. The role of the armor microstructure in defeating threats as well as providing avenues of energy dissipation to withstand biting attacks is identified. Microstructural length scale and material property matching between the threat and armor is clearly observed. Bilayered and quadlayred models are mechanically comparable, but the quad-layer model achieves a weight reduction. Studies of predatorprey threat-protection interactions may lead to insights into tunability in mechanical functionality of each system in conjunction with adaptive phenotypic plasticity of the tooth and scale microstructure and geometry, "adaptive stalemates," and the so-called evolutionary "arms race." The second model system, Gasterosteus aculeatus, is well-known for light-weight and morphologically varied armor structure among different G. aculeatus populations. Marine and freshwater G. aculeatus armor structures have been assessed quantitatively by micro-computed tomography ([mu]CT) technique. The convolution of plate geometry in conjunction with plate-to-plate overlap allows a relatively constant armor thickness to be maintained throughout the assembly, promoting spatially homogeneous protection and thereby avoiding weakness at the armor unit interconnections. Plate-to-plate junctures act to register and join the plates while permitting compliance in sliding and rotation in selected directions. SEM and [mu]CT revealed a porous, sandwich-like cross-section of lateral plates beneficial for bending stiffness and strength at minimum weight. Moreover, the structural parameters of the pelvic assemblies were also quantified via pCT, which include the spatial dependence of the suture amplitude and frequency, the suture plate inclination angle, and the suture gap. Significant differences in these structural parameters were observed between the different G. aculeatus populations. Composite analytical and finite element computational models were developed and used in conjunction with the pCT data to simulate the mechanical behavior of the pelvic assembly, to predict the effective suture stiffness and to understand the conformational change of the pelvic assembly from the "rest" to "offensive" states. This study elucidates the structural and functional differences between different divergent populations of G. aculeatus and serves as a model for other systems of interest in evolutionary biology.
by Juha Song.
Ph.D.
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Bih, Awa Solange. "The parasites of Callorhinchus capensis (St. Joseph elephant fish)." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/10072.
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Includes bibliographical references.The extent of parasitism by macroscopic parasites was assessed and the relationships between the parasites and their fish hosts in terms of sex, size and the condition factor of the fish were investigated.
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Harvey, Joel. "Environmental factors affecting Methylmercury in fish of the Laurentian Great Lakes region." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1421076009.
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Blawut, Bryan Joseph. "Assisted Reproduction Techniques’ Effects on Sperm Physiology of the Freshwater Fish, Sauger (Sander canadensis)." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1607012858031537.
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Cho, Jamie L. (Jamie Lee) 1974. "Electronic subsystems of a free-swimming robotic fish." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/46192.
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Gurunathan, Mohan 1975. "Guidance, navigation and control of a robotic fish." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50052.
Full textAbstract:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 70).
by Mohan Grurnathan.
S.B.and M.Eng.
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Bouska, Wesley Wade. "Road crossing designs and their impact on fish assemblages and geomorphology of Great Plains streams." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1084.
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Yanos, Casey Lee. "Effects of Productivity Gradients on Fish Community Structure in Lake Erie." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1483546630641725.
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Ulrich, Robert Michael. "RNA Detection Technology for Applications in Marine Science: Microbes to Fish." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5321.
Full textAbstract:
The accurate identification of taxa from mixed assemblages using genetic analysis remains an important field of molecular biology research. The common principle behind the development of numerous documented genetic detection technologies is to exploit specific nucleotide sequences inherent to each taxon. This body of work focuses on practical applications of real-time nucleic acid sequence-based amplification (RT-NASBA) in marine science, and is presented in four case studies. Each study represents novel work in the genetic identification of respective taxa of interest using RT-NASBA. Two case studies documented the development of an assay targeting mitochondrial 16S rRNA to discern legally salable grouper species in the U.S. from fraudulently mislabeled surrogate fish. This technology was first validated using lab-based, benchtop instrumentation, and was then adapted into a complete field detection system. The third study documented an internally controlled RT-NASBA (IC-NASBA) assay for the detection and quantification of the harmful algal bloom-causing dinoflagellate, Karenia mikimotoi, by targeting the ribulose-1, 5-bisphosphate carboxylase-oxygenase (RuBisCO) large-subunit gene (rbcL). The final section of this dissertation details the preliminary development of an IC-NASBA assay targeting large subunit rRNA for the quantification of Enterococcus, which is a genus of bacteria commonly used as an indicator of fecal pollution in recreational marine water. My results show that RT-NASBA provides a suitable format for the accurate identification of target species from these taxa which include prokaryotes, as well as both unicellular and multicellular eukaryotes.
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Haase, Maxwell D. "Effects of the Algal Toxin Microcystin on Fishes in the James River, Virginia." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3941.
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With the global rise in frequency of harmful algal blooms in estuarine environments comes an increase in prevalence of toxic metabolites, such as microcystin (MC), that some of the cyanobacteria involved will produce. At high concentrations, MC may accumulate in consumer tissues and have deleterious effects on organisms; however impacts of the toxin on aquatic living resources at ecologically relevant concentrations have not been widely documented. We analyzed the effects of MC on juveniles of five fish species from the James River, Virginia to determine if MC has the potential to impede growth. Using three separate experimental approaches, it was shown that exposure to concentrations of the toxin currently observed in the James River estuary do not appear to significantly impact the growth or survivorship of tested fish species. Extraneous factors in parts of the study led to an inability to draw clear conclusions on mortality or growth impacts; however it is evident from the experiments that at least some of the fish species have biological mechanisms in place that allow them to effectively eliminate the toxin from their systems. An ability to extricate the toxin suggests the possibility for fishes to withstand MC exposures and sustain few negative health impacts at low MC concentrations.
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Eitzmann, Jeffrey Laine. "Spatial habitat variation in a Great Plains river : effects on the fish assemblage and food web structure." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/557.
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Geldenhuys, Dale Adam. "Quantitative fish survey of the submarine canyons of the iSimangaliso Wetland Park." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15512.
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There have been no quantitative studies of fish species associated with the submarine canyons of the north east coast of South Africa. These canyons offer protection to coelacanths Latimeria chalumnae, fish of commercial importance, and a number of protected and endemic species. A fish survey was conducted by remotely operated vehicle (ROV) that captured video footage at depths between 60 m and 160 m. Seven canyons (Island Rock, South Island Rock, Wright, Jesser, Diepgat, Leadsman and Chaka) and one deep reef (Diepgat Deep Reef) spread along 78 km of shelf break were surveyed. Fish were identified and counted in 1143 30-second video segments. Patterns in diversity and abundance were investigated with respect to canyon, depth, and habitat type. The survey found 52 fish species from 23 families. The families Serranidae and Sparidae were well represented. The first submarine images of the critically endangered Seventy†Four seabream are particularly noteworthy. Only three Myliobatidae species represented the Chondrichthyans. Variation in Shannon-Wiener species diversity (H') was influenced by the diversity of habitat (Kruskall†Wallis p<0,0001) and depths (Kruskall†Wallis p<0,0001). Mann†Whitney post hoc tests showed cave to have a higher H' than sandy plain (p<0,001) and wall (p<0,001). H' for margin was greater than sandy plain (p=0,001) and wall (p<0,001). H' for rock outcrop was greater than sandy plain (p=0,006). Fish diversity increased with increasing depth until 90m, thereafter diversity decreased with subsequent depths. Habitat (Permanova p=0,0031) had the strongest influence on fish community composition. No north†south separation in terms of fish diversity (H') among canyons was detected. The results were consistent with similar studies. All canyons were adequately sampled as the rate of discovery of additional species per sample was ≤1%. A minimum of 80 30-second samples per canyon is recommended to survey fish. The survey methods employed during this study are recommended for surveying deep reef fish to allow for meaningful comparative studies.
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Mbatha, Fisokuhle Lungile. "Environmental variables influencing spatial and temporal patterns of fish spawning and recruitment." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25402.
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ABSTRACT Spawning times and spawning intensity during the life cycles of some fish species found off South Africa and Norway were synthesized using data collected from the literature. The comparison of temporal patterns in spawning of South African fish species showed variable spawning times and intensity depending on the environmental conditions within that spawning habitat. Their spawning migration durations were suggested to be short since they inhabit a dynamic coastal upwelling ecosystem with intra-seasonal differences caused by changes in upwelling strength enhanced by south-easterly winds, nutrient-limited waters on the spawning grounds and stable thermal conditions. This contrasts with Norwegian fish species, which showed patterns of spawning times and durations that are restricted and confined to spring (February – May), probably due to strong, consistent seasonality, depending on primary production. This explains the inter-annual differences observed in their spawning periods, where strong south-westerly winds (downwelling), light intensity and salinity stratification could influence long spawning migrations. For Cape hakes, environmental variability influencing recruitment was further investigated on the west coast nursery grounds of the southern Benguela, particularly for deep-water Cape hake (Merluccius paradoxus). Biophysical characteristics of the west coast nursery grounds were assessed in relation to distribution of deep-water Cape hake juveniles (< 15 cm) using physical data (CTD, alongshore wind speed anomalies) and biological data (abundance/density of hake juveniles, recruitment estimates). Distinct spatial patterns of hake distribution were evident in relation to near-bottom environmental factors (temperature, salinity and oxygen). Nansen surveys conducted from 2003 – 2013 during summer (January – February) showed greater abundance of hake juveniles over the Orange Banks than in other nursery areas. The hake juveniles occurred in mid-shelf waters with oxygen depletion (2 – 3 mL O₂.L⁻¹) and hypoxic conditions (< 2 mL O₂.L⁻¹) and temperature ranges of 7 – 11 ⁰C. Salinity appeared to have less influence on hake juveniles' distribution. During spring surveys, hake catches were reduced on all nursery grounds except near Cape Columbine. There was a strong positive correlation between deep-water Cape hake recruitment indices and summer wind speed anomalies for the same year (Lag = 0 year) and with autumn wind speed anomalies of the previous year (Lag = 1 year). The relationship between winds and near-bottom oxygen concentrations on the Orange Banks is unclear and needs to be investigated.
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Rittinger, Madi. "The Effects of Domestication on Aggression in Fish." Ohio Dominican University Honors Theses / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=oduhonors1494230931148878.
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Trifonova, Neda. "Machine-learning approaches for modelling fish population dynamics." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/13386.
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Ecosystems consist of complex dynamic interactions among species and the environment, the understanding of which has implications for predicting the environmental response to changes in climate and biodiversity. Understanding the nature of functional relationships (such as prey-predator) between species is important for building predictive models. However, modelling the interactions with external stressors over time and space is also essential for ecosystem-based approaches to fisheries management. With the recent adoption of more explorative tools, like Bayesian networks, in predictive ecology, fewer assumptions can be made about the data and complex, spatially varying interactions can be recovered from collected field data and combined with existing knowledge. In this thesis, we explore Bayesian network modelling approaches, accounting for latent effects to reveal species dynamics within geographically different marine ecosystems. First, we introduce the concept of functional equivalence between different fish species and generalise trophic structure from different marine ecosystems in order to predict influence from natural and anthropogenic sources. The importance of a hidden variable in fish community change studies of this nature was acknowledged because it allows causes of change which are not purely found within the constrained model structure. Then, a functional network modelling approach was developed for the region of North Sea that takes into consideration unmeasured latent effects and spatial autocorrelation to model species interactions and associations with external factors such as climate and fisheries exploitation. The proposed model was able to produce novel insights on the ecosystem's dynamics and ecological interactions mainly because it accounts for the heterogeneous nature of the driving factors within spatially differentiated areas and their changes over time. Finally, a modified version of this dynamic Bayesian network model was used to predict the response of different ecosystem components to change in anthropogenic and environmental factors. Through the development of fisheries catch, temperature and productivity scenarios, we explore the future of different fish and zooplankton species and examine what trends of fisheries exploitation and environmental change are potentially beneficial in terms of ecological stability and resilience. Thus, we were able to provide a new data-driven modelling approach which might be beneficial to give strategic advice on potential response of the system to pressure.
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Corrales, Jone. "Antimicrobial Polypeptides, Piscidins and Histone-Like Proteins, in Important Aquacultured Fish and the Effect of Nutrition on their Expression and Susceptibility to Infection in Hybrid Striped (Sunshine) Bass (Morone saxatilis â x M. chrysops â)." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-05052008-171103/.
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Innate immunity is the initial response of a host in defending against pathogen invasion (Beutler 2004, Janeway and Medzhitov 2002). The key features of an innate immune response are that it is: non-specific (broad-spectrum), rapid (often within minutes to hours) and conserved in its pattern of recognition. Antimicrobial polypeptides (AMPP) are a key component of the innate system and present in virtually all life forms (Zasloff 2002). One of the most widespread AMPP in fish are the piscidins. Piscidins have potent, broad-spectrum activity against viruses (Chinchar et al 2004), bacteria (Silphaduang and Noga 2001), fungi (Lauth et al 2002) and parasites (Colorni et al, Accepted). Another family of AMPP are histone-like proteins (HLPs), which are highly homologous to core nuclear histones (Robinette et al 1998, Noga et al 2002). Because disease is often the major cause of economic losses in fish farming, understanding how stress affects innate immunity (e.g., expression of AMPP) and thus disease susceptibility could be highly beneficial to the industry. One very important factor that can contribute to stress in aquaculture is inadequate nutrition. Feed is the single largest expenditure in semi-intensive and intensive farms (Lunger et al 2007, Twibell et al 2003, Mbahinzireki et al 2001). Thus, reducing feed costs while still maintaining optimal health is critical for successful production. As nutrient intake decreases, metabolic processes are impaired and susceptibility to disease increases. I anticipated that this would be reflected in the levels of piscidins and HLPs. The overall goal was to investigate the levels of these antibiotics that indicate fish are stressed prior to any pathological signs. For this first, an ELISA for piscidin 4 was developed and validated and its application to asses stress was confirmed. Using this ELISA and various other independent assays the presence of piscidin 4 related AMPP were detected in important aquacultured fish. Next, I found that nutritional deprivation has a deleterious effect on piscidin 4 expression and that susceptibility to an ich increases in hybrid striped bass (Morone saxatilis âx M. chrysops â). The nutritional deprivation also lead to dermatological condition in channel catfish.
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Sundell, Andreas. "Uppsättning av flow-FISH-metod för bedömning av relativ telomerlängd." Thesis, Umeå universitet, Biomedicinsk laboratorievetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-161795.
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Lubbe, Beatrix. "Characterisation and utilisation of microbes in the production of fish sauce and paste." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51649.
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Thesis (MSc Food Sc )--Stellenbosch University, 2000.ENGLISH ABSTRACT: Fermented fish products are popular food products mainly consumed and produced in Southeast Asia. These products are not produced in South Africa, and those available to the public are imported. The main action during the production and fermentation of this sort of product, is that of proteolysis, either by the bacteria or enzymes naturally present in the fish. The prevalent microbes present in six fermented fish samples from Bangkok (Thailand) and seven from Khon Kaen (Thailand), were determined, and using numerical methods, clustered into similarity groups using the calculated dendrogram .distance (Do) technique to determine their relation to reference strains. Forty-seven different bacterial strains were isolated, but no yeasts, moulds or lactic acid bacteria were found. Five Gram-negative, oxidase-positive species, five different Staphylococcus species and nine different endospore-forming species of the genus Bacillus, were isolated and identified using the API systems. The data indicated that members of the genus Bacillus were the prevalent organisms in all the products examined. The isolates were also scanned for general enzyme activity using the API Zym technology, and the production of proteases was investigated using the Standard Methods Caseinate and the Universal Protease Substrate methods. It was found that most of the isolated organisms produced protease, which is of major importance in the production of fermented fish products. Proteolytic cultures from the fermented fish products, as well as lactic acid starters, were used in the production of a fermented fresh water fish product. Production parameters including: glucose, inoculum, moisture content and incubation time, were evaluated in order to select optimum fermentation conditions. Fermentation efficiency was determined by measuring the final pH, titratable acid and the free amino nitrogen content. Optimum efficiency was obtained with 5% (w/w) added glucose at a moisture level of 150 ml water per 100 g fish. A factorial design (3 x 3 x 3) was used to indicate viable trends to facilitate optimisation of the fermentation process. The main effects, two-factor and three-factor interactions were calculated. Optimum trends obtained were a glucose concentration of 5% (wlw) , inoculum concentration of 1x10⁸ kve.ml ̄ ¹, an incubation period of 15 days and temperature of 30°C. Three lactic acid starters (226 - Lactobacillus plantarum, 140 - Lactococcus diacetylactis and 407 - Pediococcus cerevisiae) were selected as they produced some of the best fermentation results and are safe to use in food. It was found that a combination of all three strains (226, 140 and 407) yielded the best results. By using the above parameters, an acceptable product was produced in terms of consistency, colour and aroma. Further studies need to be conducted to optimise the safety of the product as well as the flavour, both chemically and sensorically optimisation of the product.
AFRIKAANSE OPSOMMING: Gefermenteerde visprodukte is populere voedselprodukte in die lande van Suidoos-Asie. Die produkte word nie in Suid-Afrika geproduseer nie, maar slegs ingevoer. Die hoof aksie tydens die fermentasie proses is proteolise deur die bakteriee en ensieme wat natuurlik teenwoordig is in vis. Die oorheersende mikrobes teenwoordig in ses gefermenteerde vis produkte van Bangkok (Thailand) en sewe van Khon Kaen (Thailand), is bepaal. Numeriese metodes is gevolg om die isolate in groepe te sorteer en te groepeer deur gebruik te maak van die berekende dendrogram afstand (Do) tegniek om hul verwantskap ten opsigte van die verwysingsorganisme te bepaal. Sewe-en-veertig verskillende bakteriee is ge·isoleer, maar geen fungi of melksuurbakteriee is ge·identifiseer nie. Vyf Gram-negatiewe, oksidase-positiewe spesies, vyf verskillende Staphylococcus spesies en nege verskillende endospoorvormende spesies van die genus Bacillus, is geisoleer en ge·identifiseer deur gebruik te maak van die API CHB sisteme. Die data het getoon dat lede van die genus Bacillus die oorheersende organismes was. Die isolate is daarna ondersoek vir algehele ensiemaktiwiteit deur van die API Zym tegnologie gebruik te maak. Daar is veral klem gelê op die protease aktiwiteit en dit is gemeet deur van die "Standard Methods Caseinate Agar" metode asook die "Universal Protease Substrate" metodes gebruik te maak. Daar is gevind dat die oorgrote meerderheid organismes proteolitiese ensieme produseer wat belangrik is in die produksie van gefermenteerde visprodukte. Kulture wat ge·isoleer is uit gefermenteerde visprodukte asook melkssuurkulture is gebruik vir die produksie van 'n gefermenteerde varswater visproduk. Produksieparameters insluitende: glukose-, inokulum- en voginhoud asook inkubasie tyd is ondersoek om die optimum fermentasie kondisies te bepaal. Optimum effektiwiteit is gevind by 'n 5% glukose konsentrasie en vogvlakke van 150 ml water per 100 9 vis. 'n Faktoriale ontwerp (3 x 3 x 3) is gebruik om die optimum kondisies te bepaal. Die hoof effekte asook die twee faktor en drie faktor interaksies is bereken. Optimum neigings is gevind by 'n glukose konsentrasie van 5%, inokulum konsentrasie van 1x10⁸ kve.ml ̄ ¹, 'n inkubasie tydperk van 15 dae en temperatuur van 30°C. Drie melksuurbakteriee (226 - Lactobacillus plantarum, 140 - Lactococcus diacetylactis en 407 - Pediococcus cerevisiae) is gekies aangesien hulle die beste resultate gelewer het en veilig vir gebruik in voedselprodukte is. Daar is gevind dat die drie melksuurkulture saam in kombinasie die beste fermentasie resultate opgelewer het. Deur gebruik te maak van die bogenoemde fermentasie kondisies, kon 'n aanvaarbare produk, in terme van kleur en geur, gelewer word. Verdere studies moet gedoen word om die veiligheid asook die geur, chemies asook sensories, te optimiseer.
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Towne, Kristen Marie. "Sex Reversal in Yellow Perch (Perca flavescens) to Produce Functional Neomale Sperm Donors." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu148063934730826.
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Finley, Mary Carmel. "The tragedy of enclosure fish, fisheries science, and U.S. foreign policy, 1920-1960 /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://nsgl.gso.uri.edu/casg/casgy07001.pdf.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed January 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Peskin, Jonah T. (Jonah Timothy) 1977. "Force control of electro-hydraulic actuators in an underwater fish-like vehicle." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86874.
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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 60-61).
by Jonah T. Peskin.
M.Eng.and S.B.
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Jackson, Latonya. "The Effects of 17alpha-ethinylestradiol in the Live-Bearing Fish Heterandria formosa." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10163310.
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This study assed the impacts of 17α-ethinylestradiol in Heterandria formosa. These impacts were addressed through chronic, life-cycle exposures of individuals and populations of least killifish to 0, 5, or 25ng/L EE2. Development, growth, reproduction, survival, and population dynamics were monitored and evaluated for EE2 effects on their health, reproductive success, and population sustainability.
Exposing pairs of least killifish to EE2 resulted in similar increases in time-to-sexual maturity for both sexes. The EE2-exposure had a sex-dependent effect on body size, with standard lengths and wet weights of females significantly reduced and standard lengths of males markedly increased. Offspring production decreased by 50% and 75% for fish exposed to 5 and 25ng/L EE2 respectively. Sexual development was even further delayed in EE2-exposed offspring of exposed fish. EE2-exposure also affected the gonadal and liver development in least killifish. Males exposed to EE2 had delayed sperm maturation and severe intersex (a phenomenon in which eggs and sperm are produced within the same male). These effects were more severe at the 5ng/L than at the 25ng/L EE2 concentration. Exposing females to EE2 resulted in delayed egg maturation. Furthermore, EE2 exposure resulted in changes in liver morphology in both males and females. For both the delay in egg maturation and the changes in liver morphology, the effects were strongest at the higher EE2 concentration.
Effects of chronic EE2-exposure on populations were assessed at the 5ng/L concentration. EE2-exposure caused significant reductions in population size and population growth rates, and caused other changes in population dynamics. Exposed populations had a pronounced female-biased sex ratio and significantly reduced abundances of males and newborns. These responses were observed within one breeding season.
This is the first report demonstrating a variety of negative impacts resulting from chronic EE2-exposure in least killifish at both the individual and population levels. Effects were evident in all stages of development and in all life history stages. This study demonstrated that, similar to the case for other fish, live-bearing fish are likely to be severely affected when their environment becomes contaminated by EE2 and that steps are needed to prevent exposure to this endocrine disrupting chemical.