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Bjorgo, Kimberly A. "Distributional ecology of Kanawha River fish." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4814.
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Thesis (Ph. D.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains vii, 195 p. : ill. (some col.), col. maps. Vita. Includes abstract. Includes bibliographical references.
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Andradi-Brown, Dominic A. "Fish ecology of mesophotic coral ecosystems." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:045dcd0d-8064-4b4e-bcad-8a8dce855b40.
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Mesophotic coral ecosystems (MCEs; reefs 30-150 m depth) are largely unstudied. This thesis uses the shallow reef to MCE depth gradient around Utila, Honduras, to address research questions in three themes: (i) understanding fish community ecological processes on MCEs; (ii) evaluating effective survey techniques for MCE fish research; and (iii) exploring the role of MCEs in the western Atlantic lionfish invasion. Around Utila, herbivorous reef fish declined with increasing depth, but remained present on MCEs, suggesting a possible role in structuring mesophotic benthic communities. To test this I artificially excluded fish from areas of the reef with controls for changing light levels. The results indicate strong effects of light availability on MCE hard coral, macroalgal and sponge coverage, while little detectable effects of fish exposure. Fish surveys play a crucial role in informing reef management, yet few studies consider how biases in survey techniques varies across depth gradients. I explored differences between baited-remote underwater video (BRUV) and diver-operated video (DOV) finding BRUVs consistently recorded more species regardless of depth, but that DOV is likely better for surveys of herbivores. I also assessed fish responses to divers using open-circuit SCUBA or closed-circuit rebreathers (CCR) and, while both recorded similar fish abundances, CCR divers were able to approach fish more closely. In addition, I conducted a meta-analysis identifying widespread invasion of western Atlantic MCEs by Indo-Pacific lionfish, with similar relative abundance distributions across the depth gradient to native range sites. Around Utila, MCE lionfish occurred at greater densities than on shallow reefs, with MCE individuals larger and more mature than their shallow counterparts. This suggests deeper lionfish populations may represent an extension of ontogenetic migrations, and act as a disproportionately large source of new lionfish recruits. Overall, this thesis provides insights applicable to the western Atlantic region more generally and highlights the need for MCEs to be considered by reef managers.
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Dorucu, Mustafa. "Ecology of helminth infections in salmonid fish." Thesis, University of Glasgow, 1996. http://theses.gla.ac.uk/2391/.
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The ecology of helminth infections has been investigated in Scottish salmonid fish populations. Examination of 240 brown trout and 49 rainbow trout from 21 locations in Central Scotland indicated that Crepidostomum farionis (Digenea) was the most widely distributed helminth species, followed by Eubothrium crassum (Cestoda), Diphyllobothrium dendriticum and Diphyllobothrium ditremum (Cestoda), Neoechinorhynchus rutili (Acanthocephala), Echinorhynchus truttae (Acanthocephala), Eustrongylides sp (Nematoda), Capillaria salvenlini (Nematoda), Cyathocephalus truncatus (Cestoda), Raphidascaris acus (Nematoda) and cystidicola farionis (Nematoda) in that order. The wide distribution of Crepidostomum farionis may be explained through the variable habits of the definitive host species and possibly interactions with human and avian factors. The frequency distribution of numbers of worms per fish was observed to be overdispersed. Autogenic species were generally the dominant form and responsible for the most of the similarity in patterns of infection within and between localities. No evidence was found to indicate host morbidity due to the helminth infections. An analysis of pairs of associations between species of helminths revealed a significantly positive association between N. rutili and C. farionis. This may be because one species improves either the establishment or survival of the other. In contrast, there was no clear evidence of competition between helminth species. The results of this study were discussed in terms of observed patterns in the helminth communities in fresh water fish host. The endoparasitic helminth fauna was examined from three sympatric morphs of Arctic charr, Salvelinus alpinus, (small-headed benthic, large-headed benthic and pelagic) from Loch Rannoch, Scotland. Six species of endoparastic helminth were recovered from the fish and the morphs had different patterns of infection. Overall, infections in pelagic charr were heavier than in the large-headed benthic morph, which in turn was heavier than in small-headed benthic even though the benthic morph lives longer than the pelagic.
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Hazlerigg, Charles Rupert Edward. "Fish population ecology and ecological risk assessment." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9678.
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Density-dependent processes are crucial in the regulation of fish populations and strongly influence their resilience to exploitation and exposure to toxic chemicals. Multiple density-dependent processes occur at different stages in the life-cycle of fish, and a general pattern of such processes in the ontogeny of fish has been suggested but not clearly demonstrated in natural populations. This thesis aimed to provide a detailed experimental assessment of density-dependent processes through the entire life-cycle, using laboratory and semi-natural populations of zebrafish, Danio rerio, and to explore the implications of these processes for the ecological risk assessment of endocrine disrupting chemicals using an individual-based population model. Results clearly demonstrate the importance of density-dependent mortality in the early juvenile life-stage and density-dependent growth in the late juvenile and adult life-stages consistent with evidence from wild populations of much larger wild species, suggesting the existence of general ontogenetic patterns of density dependence that are invariant to maximum size. Patterns of density dependence found in populations of zebrafish under semi-natural conditions in Bangladesh were similar to those observed in the laboratory, except that the absolute strength of density dependence was higher and consequently, carrying capacity lower, by about two orders of magnitude in the semi-natural populations. A conclusion from these studies is that these patterns of density dependence are applicable generally across the teleost taxa due to developmental similarities. The population model incorporating these patterns of density dependence showed that density dependence compensated for reasonably high levels of disruption for many individual-level endpoints currently used in risk assessment, including fecundity and sex ratio. This indicates that current risk assessment practices are highly conservative and the inclusion of population models such as developed here for zebrafish, could enhance the scientific basis and ecological realism of laboratory derived data used in risk analysis.
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Bird, David Jonathan. "The response of fish to electricity and its applications in fish population ecology." Thesis, University of Lincoln, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258772.
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Mahmud, Muayad Ahmed. "Evolutionary ecology of virulence in a fish parasite." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32945/.
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Virulence (parasite- induced host fitness reduction) is thought to correlate positively with pathogen reproduction rates, but its relationship with pathogen transmission is likely to be determined by a trade- off between the costs and benefits of harming hosts. This project aims to investigate factors which affect host-parasite interactions and particularly those which may play a role in virulence evolution. In doing so, it describes experiments carried out using a monogenean ectoparasitic flatworm (Gyrodactylus arcuatus) and its three-spined stickleback (Gasterosteus aculeatus) host. Populations of this fish species experience a range of both environmental and ecological conditions. Such environmental heterogeneity has been found to drive changes in fish phenotypic traits such as morphology, behaviour, life history and physiology which may consequently affect parasite fitness. I demonstrate that under these conditions, parasite strains from different host populations evolve variation in virulence levels. I also reveal that coevolution in this host parasite system is likely to lead to local adaptation of G. arcuatus at the host population level. I show that competition between parasite species sharing a single host leads to increased parasite reproduction rates, but it shortens the infection time which may be due to earlier stimulation of host immune responses. I show that virulence is neither influenced by the population density, immunity (epidermal mucus), social behaviour of fish hosts nor the natural parasite life expectancy. Lastly, I find that virulence in this system is negatively influenced by the density of stickleback predators and positively associated with loch water pH. Taken together, these results suggest that in this host parasite system, both ecological and environmental factors which drive phenotypic changes in fish hosts may evolutionarily feedback to affect parasite virulence.
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Siebeck, Ulrike Elisabeth. "UV vision and visual ecology of reef fish /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16520.pdf.
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Andrade, Pedro de Moraes [UNESP]. "Distribuição, dieta e ecomorfologia das espécies de peixes no sistema do Ribeirão Grande, no município de Pindamonhangaba, SP." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/106577.
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andrade_pm_dr_rcla.pdf: 716893 bytes, checksum: 746a97644a6d9cec3d6a533c402e7e7e (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O primeiro capítulo trata da estrutura espacial e temporal das assembléias na bacia do ribeirão Grande. Após verificar que a dimensão espacial foi a mais importante para explicar a variabilidade das assembléias amostradas, realizou-se uma análise correlativa mais detalhada da distribuição espacial e diversidade de espécies em relação a variáveis ambientais. Os resultados indicaram que características físicas e químicas da água e fisiográficas do trecho amostrado foram importantes para definir, entre todas as espécies disponíveis, aquelas capazes de colonizarem e coexisterem em determinado trecho dos riachos. Além desta influência, que pode ser considerada abiótica, alguns testes de randomização indicaram a possibilidade de interações competitivas como importantes determinantes da estrutura das assembléias, mas os resultados não foram concordantes para todas as simulações realizadas. Os pontos P6 e P7, localizados na transição entre tributários e curso principal do ribeirão Grande, foram considerados representativos de um ecótono, em que a diversidade de espécies foi maior. Este ecótono seria uma transição entre as condições ambientais dos tributários e do curso principal. Nas comunidades de peixes destes pontos apareceram espécies exclusivas do curso principal e espécies exclusivas dos tributários. Para avaliar a estabilidade das comunidades, ao longo de 1 ano, foram utilizados o coeficiente de variação e o coeficiente de correlação não paramétrico de Kendall. A estabilidade das comunidades foi avaliada em relação a duas zonas: curso principal do ribeirão Grande e seus tributários. As assembléias foram relativamente constantes durante o período de 1 ano, apesar do estudo não satisfazer as premissas necessárias para se tirar conclusões a respeito da estabilidade de comunidades...
The first chapter dealt with the spatial and temporal structure of the fish assemblages at the ribeirao Grande basin. The spatial dimension was the main source of variability in the fish assemblages, so the distribution of fish species throughout the basin were analysed with a multivariate ordination method and with linear regressions. The results of a canonical correspondence analysis indicated that the most importat variables correlated with the distribution of the ictifauna were the altitude, width and depth of the sampling stations. Variables like temperature and conductivity were probably correlates of altitude, having no causal effects in the distribution of species. Complementary distribution of closely related species were observed. Randomization tests indicated the possibility of competitive interactions in shaping the distribution of fish species in the basin. The results were not concordant, however, among the different scenarios simulated. Notwithstanding, in each scenario at least one statistic rejected the null hypotesis of random distribution of species. The sampling stations P6 and P7, located in the transition between tributaries and main channel, were considered an ecotone, where the species diversity was higher. To acess the stability of the fish assemblages were used the coeficient of variation and the non-parametric Kendall correlation coeficient The fish assemblages were stable, during a one year sampling period and the stability of communities in the tributaries was compared with the main channel. The tributaries have communites that were considered more stable than in the main channel. The second chapter dealt with the feeding relationships of the fish assemblages.The most abundant species had their stomacal contents analysed by sampling station and by sampling period. The GPA index (feeding preference degree) was used to acess the relative...(Complete abstract click electronic access below)
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Troia, Matthew John. "A mechanistic framework for understanding prairie stream fish distributions." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17285.
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Doctor of PhilosophyDepartment of Biology
Keith B. Gido
A fundamental goal of ecology is to understand environmental associations of species. These associations can provide a basis for predicting spatial distributions in contemporary habitats as well as how those distributions might change in response to anthropogenic environmental change. Developing species distribution models is limited by an incomplete understanding of functional traits, spatial scaling, and the mechanisms and generalities of correlations among abundance and environmental gradients. I address these four issues using observational and experimental approaches. First, I tested opposing mechanisms of community assembly by measuring the dispersion (i.e., diversity) of three types of functional strategies at three spatial scales and along environmental gradients. I found that communities are assembled via abiotic environmental filtering, but the strength of this filtering depends on the spatial scale of investigation, longitudinal network position, and type of functional strategy. Second, I quantified community-environment relationships across thirteen sub-basins, nested within the three major basins within Kansas to evaluate the consistency (i.e., generality) in predictive capability of environmental variables among sub-basins and across spatial extents. I found that longitudinal network position is consistently the strongest predictor of community composition among sub-basins, but in-stream and catchment predictors become stronger correlates of community composition with increasing spatial extent. Third, I used environmental niche models to quantify distributions of four pairs of congeneric cyprinids and found that species within each pair exhibited contrasting stream-size preferences. I then used field experiments to test for differences in individual-level performance between one pair of species (Pimephales notatus and P. vigilax) along a gradient of stream size. I found that adult spawn success and juvenile growth and condition increased with stream size for both species, indicating that these congeners respond similarly to abiotic gradients associated with the river continuum. I concluded that complementary distributions are a consequence of biotic interactions, differential environmental filtering evident in an unmeasured performance metric, or differential environmental filtering by an environmental factor operating at longer timescales. These studies demonstrate the context dependencies of characterizing habitat associations of stream fishes, but also reveal the general importance of stream size and associated environmental gradients in structuring stream fish communities.
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Berkelman, James. "Habitat Requirements and Foraging Ecology of the Madagascar Fish-Eagle." Diss., Connect to this title online, 1997. http://scholar.lib.vt.edu/theses/available/etd-5852152749721461/.
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Wilson, Andrew Stewart. "The effect of piscivorous fish stocking on the planktivorous fish, zooplankton, and phytoplankton communities of 31 southeastern Ontario lakes." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10417.
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Over the past 15 years a great deal of literature has been generated in an attempt to understand the regulation of trophic level biomass and size structure in aquatic systems. I tested the hypotheses that the among-lake variability in biomass and size structure of planktivorous fish, zooplankton, and phytoplankton communities depends on: (1) resource availability (bottom-up processes); (2) piscivorous sport fish stocking (top-down processes); and (3) the particular species of piscivorous sport fish stocked. We sampled 31 lakes in southeastern Ontario over the summers of 1993 and 1994 to obtain indices of abundance, biomass, and size structure of the planktivorous fish, zooplankton, and phytoplankton communities. Seven of the lakes were not stocked and the remaining 24 had stocking intensities ranging from 30 to 1500 individuals stocked per hectare over the 6 years prior to sampling. For both bottom-up and top-down analyses, trophic interactions were strongest at the base of the food web and weakened at higher levels, becoming non-significant thereafter. From these results I conclude that: (1) piscivorous sport fish stocking as a whole (at least at the magnitude examined here) had no effect on planktivorous fish, zooplankton, and phytoplankton biomass or size structure; (2) rainbow trout (Oncorhynchus mykiss) stocked lakes differ at the zooplankton and phytoplankton level from lakes stocked with other species of piscivore; (3) trophic interactions are most evident at the base of the food web (at the zooplankton and phytoplankton level); and (4) resource control (especially total phosphorus) of biomass and size structure in aquatic communities is much more important than consumer control, and it is limited to the phytoplankton and zooplankton. Our results suggest that stocking with piscivorous fish (as practised for sport fishing purposes) does not effectively manipulate plankton abundance. (Abstract shortened by UMI.)
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Waller, Samantha Jane. "Ontogenetic colour change and visual ecology of reef fish /." Online version, 2005. http://bibpurl.oclc.org/web/20815.
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Mannini, Piero. "Ecology of the pelagic fish resources of Lake Tanganyika." Thesis, University of Hull, 1998. http://hydra.hull.ac.uk/resources/hull:5722.
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Most of the scientific knowledge on the pelagic fish (the clupeids Stolothrissa tanganicae and Limnothrissa miodon and the centropomid Lates stappersii) of Lake Tanganyika is from research carried out in localised areas. This makes it difficult to extend the results to the whole lake. Consequently, there is the need to study the pelagic fish resources on a lake-wide basis using the same data collection procedures. Within the framework of an international fishery research project, data from the commercial fisheries targeting the pelagic fish stocks were simultaneously collected at various sampling sites in the riparian countries. Fishery-independent data were also obtained from lake-wide research surveys. The life histories of the three fish species appear to be similar throughout the lake. However, fish distribution across the lake is very uneven. The clupeid S. tanganicae mostly occur in the northern half of the lake and is much reduced in southern areas. This appears to be a recent contraction of the distribution range of this species. Limnothrissa miodon is more evenly distributed than S. tanganicae. The two species have a different inshore-offshore, size-related distribution across the lake. Nursery grounds of the first are close to the shore while those of S. tanganicae are in open, pelagic waters. With increase in size, S. tanganicae tend to move inshore while large L. miodon display the opposite movement. Lates stappersii stock, although relatively common, tends to be at higher concentration in the deep, steep central and southern basins. The feeding ecology of L. stappersii varies depending on the area and prey availability, but is mainly based on S. tanganicae and pelagic shrimps. Local occurrence of S. tanganicae is associated with that of copepod prey. The fish stocks experience different exploitation rates across the lake. While the fishing pressure is not excessive in the most of the lake areas, in others local overfishing is taking place. The biological characteristics of the pelagic fish species are discussed for the management of the lake fisheries. Fisheries management options are formulated on the basis of the assessment of the current exploitation levels.
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Edwards, Francois K. "Fish presence and the ecology of stream invertebrate predators." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/14773.
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This thesis describes the ecology of invertebrate predators (Plecoptera and Trichoptera) across steams, some without fish. Focusing primarily on stoneflies of the families Perlidae and Perlodidae, I studied the density and diversity of predators and the invertebrate prey, predator diet, size-mass relationships and microhabitat use. The abundance of invertebrate predators varied across streams and seasons but numbers of predatory invertebrates did not differ with fish presence. Only the smallest species of invertebrate predator was more abundant in substrate complexes in streams with fish. Overall biomass of invertebrate predators was lower in streams with fish, because the size-class distributions of some species were biased towards small individuals. The size-mass relationships and pre-emergent weights of all predators, except the Perlidae, varied across sites, but there was no clear relationship between condition and fish presence/absence. Invertebrate predators were mainly carnivorous in fishless sites, but in some species diet broadened with fish presence to include more algae. I hypothesise that the fixed nocturnal habit of Perlidae, permitted by their slower growth, accounted for the similarity in abundance, size, condition and diet across streams. Nocturnal activity and the coarse stony substrate which provided abundant refugia, minimised any effect of fish. By contrast, Perlodidae and other predators have shorter life cycles, forage by day and night, and have greater growth requirements, accounting for the greater variability in size and condition across streams. Though these species should incur greater exposure to fish, the coarse substrate may provide foraging space free from predation risk, thus minimising any effects of fish. For stream invertebrate predators, direct predation effects of fish appear to be minimal and principal effects may be sublethal, indirect, and prey mediated.
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Woodstock, Matthew. "Trophic Ecology and Parasitism of a Mesopelagic Fish Assemblage." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/469.
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Mesopelagic (open ocean, 200-1000 m depth) fishes are important consumers of zooplankton and are prey of oceanic predators. Some mesopelagic fishes (e.g., myctophids and stomiids) undertake a diel vertical migration where they ascend to the near-surface waters during the night to feed and descend into the depths during the day to avoid predators. Other mesopelagic fishes (e.g., Sternoptyx spp.) do not vertically migrate and remain at deep depths throughout the day. While in the epipelagic zone (surface – 200 m depth), vertically migrating fishes become prey to upper-trophic level predators, such as: tunas and billfishes. Benthic fishes (e.g., macrourids) often vertically migrate as well, ascending into the pelagic zone to feed on pelagic organisms. Fishes of different depths and vertical migration habits likely have a different ecological role in food webs. The relationship between parasites and gut contents provides insights into ecological processes occurring within assemblages, as prey items are often vectors for parasites. This study examined the differences between the prey items present in the gastrointestinal cavity and parasites of 26 mesopelagic fish species in the Gulf of Mexico. Results showed that based on the proportionally dominant prey items per species, six different feeding guilds existed within this assemblage, five based on planktivory: copepodivores, predators of copepods and other zooplankton, predators of copepods and euphausiids, gelatinivores, generalists, crustacean decapodivores, and upper-trophic level predators. Larger fishes preyed on larger prey items and harbored more parasites. Sigmops elongatus exhibited an ontogenetic diet shift at 75 mm standard length, progressing from eating primarily copepods at small sizes to eating primarily euphausiids at large sizes. Compared to similar studies, this study revealed a higher parasitic infestation by trematodes, an endoparasite (parasite within the host) class often restricted to nearshore hosts, in Gulf of Mexico fishes. Helicometrina nimia, the dominant parasite of the gempylid Nealotus tripes, has not previously been recorded in hosts below 200 m depth, suggesting a foodweb pathway that transitions from nearshore to offshore. These data can be used to develop and refine models aimed at understanding ecosystem structure and connectivity.
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Busst, Georgina Marie Ann. "Fish scales as ecological indicators : empirical approaches to improve their practical application to fish ecology." Thesis, Bournemouth University, 2017. http://eprints.bournemouth.ac.uk/29484/.
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The collection of scales is common when fish communities are sampled within research and monitoring programmes in freshwater fisheries. Although used primarily to age individual fish, there is increasing evidence of their potential for application to other ecological methods, yet there is also considerable uncertainty in how this can be achieved. Thus, the purpose of this research was to examine how the use of scales within age and growth studies can be enhanced and investigate their application to freshwater trophic ecology, with a particular focus on advancing their utilisation within stable isotope analysis (SIA). The research used fishes of the Cyprinidae family as the focal species. Cyprinids are of substantial global, socio-economic importance as their communities are valued ecologically, commercially and recreationally. The research assessed current methodologies, highlighted extant gaps in knowledge and sought to resolve these issues. It covered work regarding the intrinsic error contained in estimating fish age from scales and improved scale application within SIA through the provision of key data that is currently lacking within the literature. An initial invasion ecology case-study provided new insights into the growth and trophic impacts of a model native and two non-native fishes under three distinct approaches of differing spatial scale and complexity. The results revealed a range of ecological consequences for the native species from the invaders, although the extent of these was also a function of spatial scale. Additionally, a number of procedural concerns relating to the collection of fish age data and current SIA methodologies were highlighted. The use of scales to derive estimates of the ages of fish is well established, with outputs used to address questions on aspects of fish and fisheries ecology, but the process remains prone to inherent errors. The research revealed that precision of growth estimates is significantly influenced by the sub-sampling regime applied. Where individuals are long-lived and slow-growing, sub-sampling strategies that result in few scales being analysed produced imprecise data and potentially erroneous outcomes. Additionally, uncertainty in the accuracy of ageing scales also potentially results from subjective interpretation of scale features. A statistical model was developed to incorporate this uncertainty into analyses, using Bayesian statistics and a bootstrapping methodology, to improve age and growth rate estimates. The model successfully produced error adjusted von Bertalanffy growth parameters. Food web and trophic analyses have traditionally been completed through stomach content analysis, but increasingly SIA is preferred, as it provides greater temporal perspectives and requires smaller sample sizes. In fish studies, dorsal muscle tissue is typically favoured, but this is often collected destructively. The research revealed that non-destructively collected tissues, such as scales, can act as a proxy for muscle and their isotopic values can be converted with minimal error when species-specific factors are used. When stable isotope data are applied to dietary studies, their use in statistical mixing models requires accurate step-wise enrichment values between diet and consumer (i.e. discrimination factors). There is considerable uncertainty in the variability of discrimination factors between species and the influence of their diet. Consequently, specific diet-tissue discrimination factors were produced for a range of cyprinid species and diet was shown to significantly affect diet-tissue discrimination. The application of species-specific values within mixing models can result in significant differences when compared with using standard values and consideration of the influence of diet needs to be made when investigating omnivorous species. The rate of turnover of carbon and nitrogen stable isotopes was also determined and variability between tissues was revealed, indicating that species- and tissue-specific half-lives should be considered when deciding upon experimental time-frames. In summary, the research has provided substantial information targeting extant knowledge gaps relating to the application of scales from cyprinid fishes to ecological studies. Regarding fish age and growth, issues surrounding accuracy and precision of estimates has been tackled, informing researchers of the influence on precision of applying sub-sampling regimes to subsequent growth analyses and providing an original statistical tool that can improve accuracy through producing growth parameters that better reflect inherent errors in fish age data. In contributing to the use of scales in SIA, novel data have been provided that will reduce the requirement for destructive sampling of fishes and enhance present understandings of the significance of species- and tissue-specific discrimination factors and turnover rates.
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Trumpickas, Justinas. "Impacts of introduced piscivores on lake fish assemblages." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95239.
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Introduced predators can have strong negative effects on native prey populations; the severity of this impact can be greater than that of native predators and can change with multiple predator introductions. I examined relationships between native fish assemblages and five widely introduced piscivorous fishes: largemouth bass Micropterus salmoides, northern pike Esox lucius, rock bass Ambloplites rupestris, smallmouth bass Micropterus dolomieu and walleye Sander vitreus. Analysis of data from over 9000 lakes in Ontario, Canada, revealed that the presence of these piscivores reduces prey species richness, and that the magnitude of this impact varies with predator species and predator richness. There was no difference in the effects of introduced and native smallmouth bass populations on prey richness. Results from a multi-lake field study at Algonquin Park (Ontario) suggested predators structure nearshore fish assemblages, although to a lesser degree than spatial and environmental factors. There was little evidence that fish assemblages change through space and time with increased predator richness, implying functional redundancy of later invaders.L'introduction de prédateurs peut avoir de nombreux impacts négatifs sur les populations de proies indigènes; la sévérité de cet impact peut être plus important que celle que peuvent avoir les prédateurs indigènes et peut varier lors de l'introduction de plusieurs prédateurs. J'ai étudié la relation qu'il existe entre les assemblages de poissons indigènes et cinq espèces de prédateurs piscivores introduites à grande échelle: l'achigan à grande bouche Micropterus salmoides, le grand brochet Esox lucius, le crapet de roche Ambloplites rupestris, l'achigan à petite bouche Micropterus dolomieu et le doré jaune Sander vitreus. L'analyse de données provenant de plus de 9000 lacs situés en Ontario, Canada, a révélé que la présence de ces poissons piscivores réduit la richesse spécifique au niveau des proies, et que l'amplitude de cet impact varie en fonction des espèces de prédateurs et de la richesse de ces prédateurs. Il n'y a pas de différence entre l'impact que produisent les achigans à petite bouche introduits et indigènes sur la richesse des proies. Les résultats d'une enquête de multi-lac sur le terrain au Parc Algonquin (Ontario) ont suggéré que les prédateurs structurent les assemblages des poissons du littoral, bien qu'à un degré moindre que des facteurs spatiales et environmentales. Peu de preuves qui indiquent que l'assemblage de poissons change avec le temps et l'espace en fonction d'une augmentation de la richesse des prédateurs, ce qui laisse supposer qu'il y a une redondance fonctionelle des espèces envahissantes qui ont colonisé les lacs plus tard.
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Aiken, James. "Impact of piscivorous fish introduction on fish communities of small temperate lakes in Gatineau Park, Quebec, Canada." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28286.
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Small temperate lakes are under increasing pressure from a number of anthropogenic sources, including but not limited to: habitat alteration, invasive species, climate change, and pollution. In Gatineau Park, Quebec, Canada small temperate lakes have been demonstrated to be under threat from introduced piscivores, among other potential stressors. Here, I assessed the historical impact of four introduced piscivores on minnow, small fish and total fish species richness for a set of small Gatineau Park lakes. Fish community data were obtained from two previously published studies and a lake survey conducted in the summers of 2006 and 2007. I used a modified Control/Impact study design and repeated measures analysis of variance to test the hypothesis that introduced piscivores negatively affect species richness over time. My results strongly demonstrate that piscivores have had a negative effect on minnow and small fish species richness over time, whereas total fish species richness was unaffected. Assuming that these introduced piscivores pose a risk to the parks small temeprate lakes, I then assessed what lake characteristics best predict piscivore invasion risk. To do this, I estimated invasion risk employing two different analytical approaches for a total of 42 small lakes located in Gatineau Park using current and historical data collected in 1971, 1981, 1991 and 2006. Bootstrapped logistic regression was used to predict historical occurrence, and whether or not a lake was invaded/not invaded over time using predictor variables that included lake anthropogenic, spatial-isolation, and morphometric factors. For both logistic regression analyses, lake area and small fish species richness were found to be excellent predictors of piscivore invasion risk and historical occurrence, while lake spatial-isolation factors were also found to be excellent predictors of piscivore historical occurrence. The bootstrapped models with the most support based on Akaike's Information Criterion corrected for small sample size (AICc) were then used to identify lakes at greatest risk for future invasion. My results support the contention that introducing top predators into novel aquatic environments has detrimental impacts on native fish communities, and that these impacts are not always immediately obvious, but are indeed discernable over time. In conclusion, I make specific recommendations to guide the conservation and management of small temperate lake ecosystems.
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Downs, Kelsea Nicole. "ONTOGENETIC VARIATION IN THE NUTRIENT STOICHIOMETRY OF JUVENILE FISH." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1515610199095487.
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Proulx, Marc. "The effects of planktivorous fish on phytoplankton community structure." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6640.
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The response of phytoplankton to nutrient loading and planktivorous fish additions was investigated in large experimental enclosures installed in lac Croche at the Station de Biologie des Laurentides de l'Universite de Montreal. During the summer period (July and August), phytoplankton biomass significantly increased with fertilization and the presence of fish in the deep, thermally stratified, enclosures. The presence of fish increased algal biomass, particularly under the fertilized conditions. In the shallow, thermally mixed enclosures, total phytoplankton biomass was significantly affected by fertilization but not by the presence of fish. The taxonomic composition at both the species and the division levels differed in all treatments. In the deep stratified enclosures, both the addition of nutrient (p .001) and fish (p =.003) favored a large increase in Chlorophyta biomass which was composed of 1 or 2 species. Pyrrhophytes increased slightly with the presence of fish. In the shallow enclosures, nutrient additions significantly affected the division composition of total algal biomass, whereas presence of fish did not. The presence of planktivorous fish influenced phytoplankton community structure by modulating total algal biomass, the distribution of biomass according to size classes and the overall taxonomic composition. The impacts of fish were more numerous in the deep than in the shallow enclosures. Thermal stratification may thus be an important factor influencing the impact of planktivorous fish on phytoplankton. (Abstract shortened by UMI.)
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Reardon, Erin. "Fish in extreme environments: reproduction and energetics under hypoxia." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86877.
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This thesis integrates physiological and evolutionary ecology to quantify effects of hypoxia (low oxygen) on the energetic and life-history traits of the mouth brooding African cichlid, Pseudocrenilabrus multicolor. A field survey of 10 populations in Uganda indicated that dissolved oxygen (DO) is a strong predictor of interdemic variation in life-history traits. Females from low-DO sites were characterized by smaller size at maturity, and more, smaller-sized offspring than females from high DO, supporting body-size surface area predictions under hypoxia. In lab rearing and acclimation experiments, embryos and juveniles held under hypoxia and normoxia did not differ in size or survival, suggesting genetic and/or maternal effects while the young are in the mouth. Once released, juvenile growth was slower under hypoxia. In adult P. multicolor, there was evidence for effects of long-term exposure to chronic hypoxia on energetics and mouth brooding. Critical oxygen tension, an index of hypoxia tolerance, was lower in fish reared under hypoxia and similarly plastic across populations. Estimates of resting routine metabolic rate and marginal metabolic scope in the same fish indicated both plastic and genetic components of metabolic response to hypoxia. Both acclimation and rearing studies demonstrated that mouth brooding is energetically expensive and more so under hypoxia. Standard metabolic rates were ~48% higher in brooding females compared to post-brooding females regardless of DO acclimation. However, the length of the brooding period (time in the mouth) was shorter and development faster for young brooded under hypoxia, a potential strategy for dealing with the expense of offspring care under hypoxia. An implicit optimality model created to predict optimal body size in response to the combined influences of oxygen and predator pressure supported our empirical findings for smaller body size under hypoxia. An integration of this work suggests that DO plL'hypoxie (un faible taux d'oxygène dissout dans l'eau - OD) constitue un stress environnemental de plus en plus présent auquel font face plusieurs organismes aquatiques à l'échelle planétaire. Cette thèse intègre à la fois l'écologie physiologique et évolutive afin de quantifier les effets de l'hypoxie sur les traits énergétiques et d'histoire de vie d'un cichlidé africain, Pseudocrenilabrus multicolor, une espèce avec un haut taux de plasticité phénotypique pratiquant la couvaison buccale. Un inventaire de terrain a révélé que l'OD est un bon indicateur de variation « inter-groupe » (interdemic) des traits de vie. Les femelles P. multicolor provenant de sites où le taux d'OD est faible se caractérisent par une plus petite taille à maturité, ainsi que par des portées plus abondantes mais constituées d'une progéniture de plus petite taille que les femelles provenant de sites à haute teneur en OD. Ceci supporte la prédiction, basée sur les principes physiologiques, que l'hypoxie engendre une taille plus petite. Lors d'élevages en laboratoire et d'expériences d'acclimatation, la taille et la survie des embryons et des juvéniles maintenus sous des conditions d'hypoxie et sous des concentrations normales en OD ne différaient pas. Ces résultats suggèrent que ces traits pourraient être influencés par la génétique et/ou par des effets maternels. Une fois les juvéniles relâchés par la mère, la croissance était plus lente sous un contexte d'hypoxie. Chez les individus adultes de P. multicolor, nous avons observé des preuves des effets de l'exposition à long-terme à l'hypoxie sur les flux et la distribution d'énergie, ainsi que sur la couvaison buccale. La tension critique en oxygène, un indice de tolérance à l'hypoxie, était plus basse chez les poissons élevés dans des conditions d'hypoxie, mais la plasticité y étant associée était semblable entre les populations. Les estimations du taux métabolique de l
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Carr, Oliver John. "Fish-farm effluents and their effects on river biology." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328864.
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Carol, Bruguera Joaquim. "Ecology of an invasive fish (Silurus glanis) in Catalan reservoirs." Doctoral thesis, Universitat de Girona, 2007. http://hdl.handle.net/10803/7870.
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L'objectiu d'aquesta tesi és aportar les primeres dades sobre l'ecologia del silur (Silurus glanis) introduït a la Península Ibèrica i estimar els seu impacte ecològic sobre la biota nativa. Es van mostrejar les comunitats de peixos de 14 embassaments catalans. El silur es troba actualment introduït a quatre conques Ibèriques: a la de l'Ebre fa uns 30 anys, a les del Ter i Tajo fa uns pocs anys i recentment al Llobregat. Hem demostrat la utilitat de comparar estadis d'invasió recents i avançats per mirar d'entendre els canvis ecològics causats per espècies invasores: les introduccions recents presenten silurs més joves, de menor mida i amb taxes de creixement superiors a les de les poblacions introduïdes anteriorment i també respecte les poblacions natives; a més, depreden majoritàriament sobre peixos, en contra de les poblacions més antigues que s'alimenten sobretot de cranc. Finalment, aportem les primeres dades publicades de telemetria del silur.The aim of this thesis is to provide the first data on the ecology of European Catfish (Silurus glanis) introduced to the Iberian Peninsula and to appraise its ecological impact on native biota. We sampled the fish assemblage of 14 Catalan reservoirs (Spain). The European catfish is nowadays introduced in four Iberian river basins: in the Ebro river basin for 30 years, in the Ter and Tajo river basin for a few years and we report the first record for the Llobregat river basin. We demonstrate the utility of comparing early and late invasion stages to understand the ecological changes caused by invasive species: recent introductions of catfish had smaller and younger catfish with growth rates higher than old and native populations and preying on fish instead of crayfish for old introductions. We also report the first published telemetry data for catfish.
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Svanbäck, Richard. "Ecology and Evolution of Adaptive Morphological Variation in Fish Populations." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-196.
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The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. During recent years, research about individual variation in diet and morphology has gained interest in adaptive radiations and ecological speciation. Such variation among individual niche use may have important conservation implications as well as ecological and evolutionary implications. However, up to date we know very little about the extension of this phenomenon in natural populations and the mechanisms behind it.
The results in this thesis show that the extension of individual diet specialization is widely spread throughout the animal kingdom. The variation in diet is mainly correlated to morphological variation but not always. Furthermore, this variation in diet and morphology among individuals could be both genetically determined and environmentally induced and it mainly comes from trade-offs in foraging efficiency between different prey types.
The results from a number of studies of perch also show that individual perch differ in morphology and diet depending on habitat, where littoral perch has a deeper body compared to pelagic perch. This difference in morphology corresponds to functional expectations and is related to foraging efficiency trade-offs between foraging in the littoral and pelagic zone of a lake. The variation in morphology in perch is mainly due to phenotypic plasticity but there are also small genetic differences between the littoral and pelagic perch. Two separate studies show that both predation and competition may be important mechanism for the variation in morphology and diet in perch.
In conclusion, the results in this thesis show that individual variation in diet and habitat choice is a common phenomenon with lots of ecological and evolutionary implications. However, there are many mechanisms involved in this phenomenon on which we are just about to start learning more about, and only further research in this area will give us the full insight.
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Svanbäck, Richard. "Ecology and evolution of adaptive morphological variation in fish populations /." Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-196.
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Harrison, A. J. "Ecology and control of the freshwater fish louse (Argulus foliaceus)." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431598.
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Weatherley, N. S. "The feeding ecology of juvenile fish in a lowland river." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354532.
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Pennock, Casey A. "Fragmentation and fish passage: can fishways mitigate discontinuities in Great Plains fish communities?" Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34557.
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Master of ScienceDepartment of Biology
Keith B. Gido
Fishways are a common tool for mitigating the effects of habitat fragmentation on fish communities, but their utility in low-gradient, sand-bed rivers of the Great Plains is not well studied. The Lincoln Street Fishway on the Arkansas River became operational in 2015 and was built specifically to pass small-bodied threatened fishes. We used a combination of surveys up-and downstream of the barrier and tagging experiments to test the ability of fishes to move into and through the fishway. Differences in fish community structure up- and downstream of the dam were more pronounced prior to the construction and operation of the fishway. In particular, Emerald Shiner Notropis atherinoides was absent from collections upstream of the dam before fishway construction, but commonly collected upstream in 2015 and 2016 surveys. Surveys within the fishway structure revealed 29 species, or 74% of the total species captured during our study were using the fishway. To further quantify fishway passage, we used a VIE experiment to assess if fish marked downstream of the fishway moved into or upstream of the fishway. Although we did not recapture marked fish upstream of the fishway, some marked individuals moved into the fishway. Finally, we conducted a PIT tag experiment to evaluate short distance movements within the fishway for three species of small-bodied minnow and were able to document upstream movement across a gradient of flows through the fishway. Results from our study illustrate the potential for fishways to mitigate the effects of habitat fragmentation on small-bodied fishes in sand-bed rivers.
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Briland, Ruth. "Optimizing Larval Fish Survival and Growth through an Analysis of Consumer and Resource Interactions in Percid Culture Ponds." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268153735.
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Carden, Kerilynn M. "Macrophytes as fish habitat : the role of macrophyte morphology and bed complexity in fish species distributions /." Link to abstract, 2002. http://epapers.uwsp.edu/abstracts/2002/Carden.pdf.
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Andrade, Pedro de Moraes. "Distribuição, dieta e ecomorfologia das espécies de peixes no sistema do Ribeirão Grande, no município de Pindamonhangaba, SP /." Rio Claro : [s.n.], 2004. http://hdl.handle.net/11449/106577.
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Orientador: Francisco Manoel de Souza BragaBanca: Lilian Casatti
Banca: Katharina E. Esteves
Banca: Rosana Mazzoni
Banca: Leandro Muller Gomiero
Resumo: O primeiro capítulo trata da estrutura espacial e temporal das assembléias na bacia do ribeirão Grande. Após verificar que a dimensão espacial foi a mais importante para explicar a variabilidade das assembléias amostradas, realizou-se uma análise correlativa mais detalhada da distribuição espacial e diversidade de espécies em relação a variáveis ambientais. Os resultados indicaram que características físicas e químicas da água e fisiográficas do trecho amostrado foram importantes para definir, entre todas as espécies disponíveis, aquelas capazes de colonizarem e coexisterem em determinado trecho dos riachos. Além desta influência, que pode ser considerada abiótica, alguns testes de randomização indicaram a possibilidade de interações competitivas como importantes determinantes da estrutura das assembléias, mas os resultados não foram concordantes para todas as simulações realizadas. Os pontos P6 e P7, localizados na transição entre tributários e curso principal do ribeirão Grande, foram considerados representativos de um ecótono, em que a diversidade de espécies foi maior. Este ecótono seria uma transição entre as condições ambientais dos tributários e do curso principal. Nas comunidades de peixes destes pontos apareceram espécies exclusivas do curso principal e espécies exclusivas dos tributários. Para avaliar a estabilidade das comunidades, ao longo de 1 ano, foram utilizados o coeficiente de variação e o coeficiente de correlação não paramétrico de Kendall. A estabilidade das comunidades foi avaliada em relação a duas zonas: curso principal do ribeirão Grande e seus tributários. As assembléias foram relativamente constantes durante o período de 1 ano, apesar do estudo não satisfazer as premissas necessárias para se tirar conclusões a respeito da estabilidade de comunidades...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The first chapter dealt with the spatial and temporal structure of the fish assemblages at the ribeirao Grande basin. The spatial dimension was the main source of variability in the fish assemblages, so the distribution of fish species throughout the basin were analysed with a multivariate ordination method and with linear regressions. The results of a canonical correspondence analysis indicated that the most importat variables correlated with the distribution of the ictifauna were the altitude, width and depth of the sampling stations. Variables like temperature and conductivity were probably correlates of altitude, having no causal effects in the distribution of species. Complementary distribution of closely related species were observed. Randomization tests indicated the possibility of competitive interactions in shaping the distribution of fish species in the basin. The results were not concordant, however, among the different scenarios simulated. Notwithstanding, in each scenario at least one statistic rejected the null hypotesis of random distribution of species. The sampling stations P6 and P7, located in the transition between tributaries and main channel, were considered an ecotone, where the species diversity was higher. To acess the stability of the fish assemblages were used the coeficient of variation and the non-parametric Kendall correlation coeficient The fish assemblages were stable, during a one year sampling period and the stability of communities in the tributaries was compared with the main channel. The tributaries have communites that were considered more stable than in the main channel. The second chapter dealt with the feeding relationships of the fish assemblages.The most abundant species had their stomacal contents analysed by sampling station and by sampling period. The GPA index (feeding preference degree) was used to acess the relative...(Complete abstract click electronic access below)
Doutor
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Garpe, Kajsa. "Effects of habitat structure on tropical fish assemblages." Doctoral thesis, Stockholm University, Department of Zoology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6767.
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Rates of habitat alteration and degradation are increasing worldwide due to anthropogenic influence. On coral reefs, the loss of live coral reduces structural complexity while facilitating algal increase. In many coastal lagoons seagrass and corals are cleared to make room for cultivated macroalgae. This thesis deals with reef and lagoon habitat structure and how fish assemblage patterns may be related to physical and biological features of the habitat. It further examines assemblage change following habitat disturbance. Four studies on East African coral reefs concluded that both the abundance and species richness of recruit and adult coral reef fish were largely predicted by the presence of live coral cover and structural complexity (Papers I-III, VI). Typically, recruits were more selective than adults, as manifested by limited distributions to degraded sites. Paper VI compared short- and long-term responses of fish assemblages to the 1997-1998 bleaching event. The short-term response to coral mortality included the loss of coral dwelling species in favour of species which feed on algae or associated detrital resources. Counterintuitively, fish abundance and taxonomic richness increased significantly at one of two sites shortly after the bleaching. However, the initial increase was later reversed and six years after the death of the coral, only a limited number of fish remained. The influence of fleshy algae on fish assemblages was studied in algal farms (Paper IV), and examined experimentally (Paper V). The effects of algal farming in Zanzibar were significant. Meanwhile, manually clearing algal-dominated patch reefs in Belize from macroalgae resulted in short-term increases of abundance, biomass and activity of a few species, including major herbivores. The findings of this thesis demonstrate the significance of habitat as a structuring factor for tropical fish assemblages and predicts that coral death, subsequent erosion and algal overgrowth may have substantial deleterious impacts on fish assemblage composition, abundance and taxonomic richness, with recovery being slow and related to the recovery of the reef framework.
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Walker, Nicholas Mark. "The fish and fishery of Stocks Reservoir, Lancashire." Thesis, University of Hull, 1989. http://hydra.hull.ac.uk/resources/hull:3812.
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This study of the fish and fishery of Stocks Reservoir, Lancashire, is the result of contract work undertaken by the researcher for North West Water (NWW). In an attempt to describe the location of the study, relevant information covering the catchment, local geology, reservoir construction and flora and fauna is included.The Authority's remit suggested a study of three facets of the catchment, namely, a study of the native fish populations, a monitoring of the recently opened fishery and an analysis of operational filter plate impingement.In order to minimise disturbance of the sport fishery, native fish population work was necessarily limited to the reservoir's three major afferent streams, the River Hodder, Hasgill Beck and Bottoms Beck.As a preliminary measure of tributary stream status, a simple invertebrate site study was undertaken by the researcher in 1985.Fish population work based on catch per unit effort (CPUE) was pursued in the spring, summer and winter of 1985, 1986 and 1987 at 8 sites, employing D. C. electric fishing equipment, whilst Carle and Strub's (1978) MWL Method was adopted for population estimations. The validity of the electric fishing survey and age determination are discussed in the text.The native species of brown trout, bullhead, stone loach and minnow were encountered, as was the introduced rainbow trout. Species densities and the population structure of the native brown trout were examined in detail for each survey site. The River Hodder was revealed to be the least populous tributary, whilst Hasgill Beck exhibited the greatest fish densities. Spawning migrations of native brown trout were evident, with fry recruitment at its optimum at site 4 on Hasgill Beck and site 8 on Bottoms Beck. The waterfall on Bottoms Beck might well have precluded upstream access to the head waters of this tributary. Observed mean brown trout length for age data were similar to those recorded by authors researching other upland stream locations.The history of Stocks Reservoir as a sport fishery is outlined prior to the present leaseholder's opening of the reservoir as a day ticket fly fishery for the 1985 season. The water was stocked predominantly with rainbow trout, together with some brook trout and brown trout before fishing commenced.The present study covering the seasons 1985 to 1987 was based primarily on data abstracted from catch return forms, which displayed a notably high rate of submission, and stocking consent data provided by NWW. The validity of return form data is discussed.Over the three seasons studied, angler patronage was observed to decline by 16%, whilst the number of fish caught and taken also declined by 34.8% and 20.5% respectively. Angler success was similarly observed to decline in accord with the decrease in patronage and catches. Interestingly, there was an increased reliance on introductions of rainbow trout over the period, including larger fish, and by 1987 a cessation in the stocking of other trout species.From correlations observed between environmental parameters and angler patronage, anglers appeared to prefer fishing in dry, sunny conditions, but decreases in angler success occurred during periods of increased water turbidity. Such declines in success also displayed congruity with decreases in angler patronage.From a comparison undertaken with a cross-section of English and Welsh stillwater trout fisheries, Stocks Reservoir was judged to rate poorly, returning the lowest performance data in the upland stocked category.An examination of the stomach and hind gut contents of 127 rainbow trout, 7 brook trout and 8 brown trout caught by anglers, was undertaken in the 1985 and 1986 seasons, and was compared with the reservoir fauna data of Mills, M. L. (1971).A description of the water treatment plant and its operation is delineated, and a pertinent collection of fish impingement and screening literature is included.Impingement data were collated from lst March 1985 to 31st December 1987 from routine and emergency cleaning of the filter plates. After storage in a freezer, the thawed fish were examined chronologically, identified, measured and weighed. During the examinations a random sample of stomach and hind guts was procured, and scales from brown trout were removed for possible future reference.The total annual impingement was observed to vary considerably, although brown trout habitually exhibited the greatest losses, comprising 71%, 64% and 89% of fish impinged annually. Of the introduced species, rainbow trout and brook trout, brook trout were the more susceptible to impingement, but remarkably few rainbow trout were lost considering the number stocked.Rainbow trout and brook trout of medium (150mm to 300mm) and large (>300mm) length classes were impinged, whereas many smaller (<150mm) brown trout were lost, a phenomenon concurrent with the recruitment of juvenile stream fish to the reservoir population.Brown trout in particular exhibited an annual dissimilarity in rates of impingement, probably suggesting that seasonal migration was not causative of their increased impingement.Impingement of rainbow trout showed limited correlation with environmental parameters. In 1985 and 1986, increased impingement of both brown trout and brook trout was significantly correlated with low reservoir levels, and to some extent might be linked to rising values of water turbidity.The collecting of stomach and hind gut samples from impinged fish was discontinued after 1985 because of problems in collection associated with delays in sampling and probable regurgitation of stomach contents. The problem of eye fluke infestation in impinged fish was noted and enumerated as sampling progressed.A brief discussion of further routes of operational fish loss from the reservoir is included.
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Dippold, David Arthur. "Responses of an exploited fish population to environmental change." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606136495171641.
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Rosenthal, Gil Guastoni. "The behavioral ecology of visual signaling in swordtails /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Pinkerton, Jeramy John. "Predicting the Potential Distribution of Two Threatened Stream Fish Species in Northeast Ohio." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461189304.
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Moore, Cordelia Holly. "Defining and predicting species-environment relationships : understanding the spatial ecology of demersal fish communities." University of Western Australia. Faculty of Natural and Agricultural Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0002.
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[Truncated abstract] The aim of this research was to define key species-environment relationships to better understand the spatial ecology of demersal fish. To help understand these relationships a combination of multivariate analyses, landscape analysis and species distribution models were employed. Of particular interest was to establish the scale at which these species respond to their environment. With recent high resolution surveying and mapping of the benthos in five of Victoria's Marine National Parks (MNPs), full coverage bathymetry, terrain data and accurate predicted benthic habitat maps were available for each of these parks. This information proved invaluable to this research, providing detailed (1:25,000) benthic environmental data, which facilitated the development and implementation of a very targeted and robust sampling strategy for the demersal fish at Cape Howe MNP. The sampling strategy was designed to provide good spatial coverage of the park and to represent the park's dominant substrate types and benthic communities, whilst also satisfying the assumptions of the statistical and spatial analyses applied. The fish assemblage data was collected using baited remote underwater stereo-video systems (stereo- BRUVS), with a total of 237 one-hour drops collected. Analysis of the video footage identified 77 species belonging to 40 families with a total of 14,449 individual fish recorded. ... This research revealed that the statistical modelling techniques employed provided an accurate means for predicting species distributions. These predicted distributions will allow for more effective management of these species by providing a robust and spatially explicit map of their current distribution enabling the identification and prediction of future changes in these species distributions. This research demonstrated the importance of the benthic environment on the spatial distribution of demersal fish. The results revealed that different species responded to different scales of investigation and that all scales must be ix considered to establish the factors fish are responding to and the strength and nature of this response. Having individual, continuous and spatially explicit environmental measures provided a significant advantage over traditional measures that group environmental and biological factors into 'habitat type'. It enabled better identification of individual factors, or correlates, driving the distribution of demersal fish. The environmental and biological measures were found to be of ecological relevance to the species and the scale of investigation and offered a more informative description of the distributions of the species examined. The use of species distribution modelling provided a robust means for the characterisation of the nature and strength of these relationships. In addition, it enabled species distributions to be predicted accurately across unsampled locations. Outcomes of the project include a greater understanding of how the benthic environment influences the distribution of demersal fish and demonstrates a suite of robust and useful marine species distribution tools that may be used by researcher and managers to understand, monitor, manage and predict marine species distributions.
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Crampton, William G. R. "The electric fish of the upper Amazon : ecology and signal diversity." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670254.
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Horton, Tammy. "Genus Ceratothoa in wild and farmed fish : taxonomy, ecology and pathology." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391353.
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Cooke, Gavan M. "The behavioural ecology of aggression in Lake Malawi haplochromine cichlid fish." Thesis, Bangor University, 2012. https://research.bangor.ac.uk/portal/en/theses/the-behavioural-ecology-of-aggression-in-lake-malawi-haplochromine-cichlid-fish(8a0e6fe2-15b6-42f5-9324-7749b44f3dad).html.
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Aggression is ubiquitous in the animal kingdom and a major field of investigation within the area of behavioural ecology. The haplochromine cichlid fish have been used extensively in studies relating not only to the behavioural ecology of aggression but also with respect to how aggression may play a role in the spectacular diversity found within the African Great Lakes. In the first half of this thesis, I investigate the nature of aggression within the rock dwelling fish of Lake Malawi. Aggression biases within polymorphic populations are initially investigated with field work determining the consequences of rare morph advantage. This is followed by experiments determining which cues males and females may use; lastly a pair of recently diverged allopatric species is studied to determine what may happen should secondary contact occur. The second half of this thesis focuses on the behaviorual ecology of female aggression. Females exhibiting the ancestral condition of post brood care are compared to a species with the more derived condition of no post release care. Non-maternal aggression is investigated with comparisons of the type of behavior used by males and females. When and why females are aggressive is also investigated. The results of this thesis suggest that overall a common morph bias may exist in some populations and the consequences are manifested in a rare morph advantage. Colour is important in aggression biases but potentially not limited to the dorsal region. Females and males use different kinds of aggressive behaviors and brooding females are able to vary levels of aggression towards different types of threat.
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Glasspool, Anne Fiona. "Larval distribution, population structure and gene flow in Bermuda's reef fish." Thesis, Cardiff University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387188.
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Pitts, Colin Stephen. "Inter-specific hybridization in the fish family Cyprinidae." Thesis, University of Hull, 1994. http://hydra.hull.ac.uk/resources/hull:5372.
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The breakdown of reproductive isolation leading to inter-specific hybridization is a widespread phenomenon amongst cyprinid fishes. There are seventeen cyprinid species occcurring in the British Isles, within five sub-families, giving rise to some ten different types of hybrid. Most of these belong to the sub-family Leuciscinae. The most commonly occurring hybrids are probably those between roach, Rutilus rutilus (L.), and common bream, Abramis brama (L.). In this study the phenomenon of hybridization amongst species of the Cyprinidae was investigated through: an experimental breeding programme to investigate the nature of inter-species and hybrid gamete compatibilities; the identification of species and hybrids from the experimental breeding programme through the analysis of morphometric, meristic and genetic characters (genetic characters were analysed using enzyme electrophoresis); the comparison of morphmetric, meristic and genetic information of natural fish with similar features of fish from the experimental breeding programme to identify the occurrence of post Fl hybridization in natural populations; the use of restriction enzyme analysis of mitochondrial DNA to elucidate the importance of maternal ancestry in a natural hybrid population. The breeding programme found, for the species in this study, that there was no success in cross-fertilization of taxa between different sub-families. Interspecific gamete compatibility was only found within the leuciscine sub-family. In cases where a hybrid cross produced progeny it was also noted that the reciprocal cross was successful. This suggests that there is not a genetic barrier to gamete compatibility resulting from the sexual directionality of a hybrid cross. Female roach/common bream hybrids also produced progeny when crossed with males of leuciscine species. Identification of the progeny of the experimental breeding programme showed that the genetic techniques of enzyme electrophoresis was more reliable than the statistical analysis of meristic and morphometric traits in the identification of species and their Fl hybrids. However, genetic information alone cannot establish precisely the nature of post Fl hybrids and in the identification of backcrossed roach/common bream hybrids it was noted that meristic information was needed to support genetic data. In the two natural hybrid populations of roach/common bream and rudd/common bream, from the Forty Foot Drain and Essex University Lake respectively, the analysis of morphometric, meristic and genetic characters found no evidence of post Fl hybridization in these waters. It is suggested that absence is due to either the limitations of the sampling methods or biological processes. Possible biological processes include factors such as the inappropriate mating behaviour of Fl hybrids or the inferior fitness of post Fl hybrids. The analysis of mitochondrial DNA did not yield sufficient results to elucidate the importance of maternal ancestry in hybridization. It is suggested that this aspect of hybridization is of such critical importance that it must become the subject of a future research programme. The importance of the causes and consequences of inter-specfic hybridization in fishes are discussed. It is suggested that, because they are rarely investigated in hybrid studies, these become incorporated into research programmes in the future. These areas of investigation will have implications for fisheries management, freshwater ecology, genetic conservation and species integrity.
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Longval, Brooke A. "Biomass spectra in Narragansett Bay from phytoplankton to fish /." View online ; access limited to URI, 2009. http://digitalcommons.uri.edu/dissertations/AAI3401124.
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Aldridge, David. "Reproductive ecology of bitterling (Rhodeus sericeus Pallas) and unionid mussels." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389425.
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Brandão, Manuela Lombardi [UNESP]. "Social isolation in a group living fish impairs cognition." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/122144.
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000812386.pdf: 239464 bytes, checksum: 801353ffc9945a91e9f0cf083777db6e (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Para se ajustar a mudanças ambientais, os animais podem aprender sobre tais variações e modular seu comportamento de acordo com suas necessidades. Em alguns casos, no entanto, mudanças no ambiente social ou físico podem gerar estados de medo que levam a respostas de estresse fisiológico e que podem modificar a capacidade de um indivíduo em aprender, impactando negativamente o bem-estar desse animal. O isolamento social, por exemplo, além de estressante para animais sociais, pode proporcionar menor estimulação para esses indivíduos. Neste estudo, nós investigamos se o isolamento social prejudica habilidades de aprendizagem no ciclídeo Cichlasoma paranaense. Dois tratamentos foram comparados, um com indivíduos isolados e outro com peixes dominantes de um grupo social. A habilidade de associar uma pista visual com a comida acessível (recompensa) foi medida em uma tarefa espacial. De fato, menos peixes isolados foram capazes de aprender a tarefa. O resultado observado não se deveu a uma diferença na motivação geral para nadar, se alimentar ou explorar as opções de forrageamento. Os resultados indicam que o isolamento social para uma espécie de peixes normalmente social pode prejudicar a aprendizagem
To adjust to changes in the environment, animals can learn about the changes to help them modulate their behaviour as needed. Sometimes, however, changes in the social or the physical environment can generate fear states that trigger a physiological stress response which modifies an individual’s capacity to learn and can have a negative impact on the welfare of the animal. Social isolation, for example, besides being sressful for social animals, may provide less stimulation for these individuals. Here, we investigated whether social isolation impairs learning skills in a cichlid fish, Cichlasoma paranaense. Two treatments were compared, one with isolated individuals and another with dominant fish from a social group. The ability to associate a visual landmark with an accessible food reward was measured in a spatial task. Overall, fewer isolated fish were able to learn the task. The result was not because of a difference in general motivation to swim, feed, or explore the foraging options. The results indicate that social isolation for a normally social species of fish can impair learning
FAPESP: 2012/10903-5
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Brandão, Manuela Lombardi. "Social isolation in a group living fish impairs cognition /." São José do Rio Preto, 2014. http://hdl.handle.net/11449/122144.
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Orientador: Eliane Gonçalves de FreitasCoorientador: Victoria A. Braithwaite
Banca: Marisa Fernandes de Castilho
Banca: Thaís Billalba Carvalho
Resumo: Para se ajustar a mudanças ambientais, os animais podem aprender sobre tais variações e modular seu comportamento de acordo com suas necessidades. Em alguns casos, no entanto, mudanças no ambiente social ou físico podem gerar estados de medo que levam a respostas de estresse fisiológico e que podem modificar a capacidade de um indivíduo em aprender, impactando negativamente o bem-estar desse animal. O isolamento social, por exemplo, além de estressante para animais sociais, pode proporcionar menor estimulação para esses indivíduos. Neste estudo, nós investigamos se o isolamento social prejudica habilidades de aprendizagem no ciclídeo Cichlasoma paranaense. Dois tratamentos foram comparados, um com indivíduos isolados e outro com peixes dominantes de um grupo social. A habilidade de associar uma pista visual com a comida acessível (recompensa) foi medida em uma tarefa espacial. De fato, menos peixes isolados foram capazes de aprender a tarefa. O resultado observado não se deveu a uma diferença na motivação geral para nadar, se alimentar ou explorar as opções de forrageamento. Os resultados indicam que o isolamento social para uma espécie de peixes normalmente social pode prejudicar a aprendizagem
Abstract: To adjust to changes in the environment, animals can learn about the changes to help them modulate their behaviour as needed. Sometimes, however, changes in the social or the physical environment can generate fear states that trigger a physiological stress response which modifies an individual's capacity to learn and can have a negative impact on the welfare of the animal. Social isolation, for example, besides being sressful for social animals, may provide less stimulation for these individuals. Here, we investigated whether social isolation impairs learning skills in a cichlid fish, Cichlasoma paranaense. Two treatments were compared, one with isolated individuals and another with dominant fish from a social group. The ability to associate a visual landmark with an accessible food reward was measured in a spatial task. Overall, fewer isolated fish were able to learn the task. The result was not because of a difference in general motivation to swim, feed, or explore the foraging options. The results indicate that social isolation for a normally social species of fish can impair learning
Mestre
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Deacon, Neil. "Determination of the optimum environmental requirements of juvenile marine fish : the development of a protocol." Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1005097.
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The spotted grunter, Pomodasys commersonnii, has been identified as a candidate species for mariculture in South Africa due to its high market demand and apparent biological suitability for culture. In common with most other potential mariculture species the spotted grunter has an estuarine juvenile phase. In this respect, the difficulties encountered in determining the optimum environmental requirements of spotted grunter are applicable to the majority of other potential mariculture species. Due the variability of estuarine habitats determination of the optimum environmental requirements of estuarine species under laboratory conditions are a prerequisite to subsequent evaluation of aquaculture potential. Therefore, using the spotted grunter as a representative of a typical potent ial mariculture species, the aim of this study was to contribute to the protocol for evaluating the environmental requirements of potential aquaculture species. The growth of fish is dependent on the relationship between food intake, metabolism and environmental factors. In this relationship, environmental factors do not act on growth per se, but rather act through metabolism on growth. Consequently, the environmental factors affecting the growth of a fish species can be classified into functional categories according to their respective influence on metabolic processes. Five functional categories are recognised, namely: controlling, limiting, masking, directive and lethal factors. In this study, the functional categories were sequenced to develop a theoretical protocol for determining the optimum environmental requirements of potential mariculture species under artificial conditions. It was hypothesised that the correct sequence for experimentally determining the optimum environmental requirements of a species should correspond to theoretical protocol. The hypothesis was tested from the experimental investigation into the individual effects of temperature, salinity, light intensity, photoperiod and food intake on growth performance of juvenile spotted grunter. The investigations quantified the relative effects of controlling, masking, directive and limiting factors on growth performance. The results of the studies were statistically compared to obtain a ranking of the effects of the environmental factors (e.g. temperature, salinity, etc.) on growth performance of juvenile spotted grunter. The statistical ranking facilitated the formulation of a second protocol for sequentially determining the optimum environmental requirements of a species. The second protocol was derived purely from the experimental data. Based on the corroboration between the theoretical protocol and that formulated from the experimental investigations, the hypothesis was accepted. Confirmation of the protocol for examining the effects of controlling, limiting, masking and directive factors provided a basis for the development of a preliminary experimental sequence for determining the optimum environmental requirements of juvenile marine fish. In the development of the experimental sequence, the protocol was interpreted in conjunction with the experimental methods used to determine the effects of environmental factors on the growth of juvenile spotted grunter. The experimental sequence provides a logical frame work within which the optimum environmental requirements of other marine fish species can be determined. In addition, evaluation of growth performance by this method provides a basis for comparison of the mariculture potential between species.
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Schmidt, Brian A. "Determining the Habitat Limitations of Maumee River Walleye Production to Western Lake Erie Fish Stocks." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1463067261.
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Newton, Paul William. "The trophic ecology of offshore demersal teleosts in the North Irish Sea." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250301.
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Amadio, Sidineia Aparecida. "The ecology of bream (Abramis brama) and rudd (Scardinius erythrophthalmus) in small eutrophic lakes." Thesis, University of Essex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282471.
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