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Artykuły w czasopismach na temat "Freshwater dispersal"
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Bilton, David T., Joanna R. Freeland i Beth Okamura. "Dispersal in Freshwater Invertebrates". Annual Review of Ecology and Systematics 32, nr 1 (listopad 2001): 159–81. http://dx.doi.org/10.1146/annurev.ecolsys.32.081501.114016.
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van de Meutter, Frank, Robby Stoks i Luc de Meester. "Size-selective dispersal of Daphnia resting eggs by backswimmers ( Notonecta maculata )". Biology Letters 4, nr 5 (15.07.2008): 494–96. http://dx.doi.org/10.1098/rsbl.2008.0323.
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Freshwater zooplankton is increasingly used to study effects of dispersal on community and metacommunity structure. Yet, it remains unclear how zooplankton disperses. Clearly, birds and wind play a significant role as zooplankton dispersal agents, but they may not always be the main vectors. This experimental study shows that a cosmopolitan aquatic insect, Notonecta , can be an important vector of cladoceran resting eggs (ephippia). Dispersing Notonecta frequently transported ephippia during flight, with a bias towards smaller ephippia in two species. A similar trend was present at the species level: Daphnia species with smaller ephippia were more often dispersed, suggesting that Notonecta could generate specific colonist communities. In addition, buoyancy appeared a critical trait, as non-floating ephippia of Daphnia magna were never dispersed. Our data suggest that Notonecta could be important dispersers of Daphnia , and that knowledge of dispersal dynamics of Notonecta may be used to predict Daphnia dispersal, colonization and resilience to disturbance.
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Comte, Lise, i Julian D. Olden. "Evidence for dispersal syndromes in freshwater fishes". Proceedings of the Royal Society B: Biological Sciences 285, nr 1871 (17.01.2018): 20172214. http://dx.doi.org/10.1098/rspb.2017.2214.
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Dispersal is a fundamental process defining the distribution of organisms and has long been a topic of inquiry in ecology and evolution. Emerging research points to an interdependency of dispersal with a diverse suite of traits in terrestrial organisms, however the extent to which such dispersal syndromes exist in freshwater species remains uncertain. Here, we test whether dispersal in freshwater fishes (1) is a fixed property of species, and (2) correlates with life-history, morphological, ecological and behavioural traits, using a global dataset of dispersal distances collected from the literature encompassing 116 riverine species and 196 locations. Our meta-analysis revealed a high degree of repeatability and heritability in the dispersal estimates and strong associations with traits related to life-history strategies, energy allocation to reproduction, ecological specialization and swimming skills. Together, these results demonstrate that similar to terrestrial organisms, the multi-dimensional nature of dispersal syndromes in freshwater species offer opportunities for the development of a unifying paradigm of movement ecology that transcend taxonomic and biogeographical realms. The high explanatory power of the models also suggests that trait-based and phylogenetic approaches hold considerable promises to inform conservation efforts in a rapidly changing world.
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Simon, Thomas P., i Jacob L. Burskey. "Spatial Distribution and Dispersal Patterns of Central North American Freshwater Crayfish (Decapoda: Cambaridae) with Emphasis on Implications of Glacial Refugia". International Journal of Biodiversity 2014 (6.11.2014): 1–7. http://dx.doi.org/10.1155/2014/282079.
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Spatial distributions of crayfish were evaluated in relation to glacial geography and possible modes of dispersal from refugia. Species dispersal patterns were a priori hypothesized and tested using principle components analysis (PCA). PCA factor loading plots were evaluated for hypothesized crayfish dispersal patterns. Cambarus laevis was limited to the unglaciated region, while Orconectes immunis, Orconectes virilis, and Procambarus gracilis may have dispersed from western glacial refugia in the upper Missouri drainage. Fallicambarus fodiens and Procambarus acutus dispersed from south of the glacial advance within the Mississippi embayment. Previous dispersal hypotheses for Orconectes propinquus recognized that northern refugia may have been from the Driftless Area in Wisconsin and Illinois and may have invaded more than one refuge since this species was common in unglaciated areas of southwestern Indiana. Orconectes indianensis center of abundance is in the unglaciated region. Disjunct populations likely dispersed into temporary glacial lakes that, when receded, left populations in previously glaciated areas. Cambarus polychromatus possibly dispersed from southern refugia, while Cambarus sp. A cf. diogenes dispersed from southern refugia not sympatric with C. polychromatus. The glacial refugia included western and southern areas of the glacial maximum; however, northern dispersal routes may be important with global climate change.
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Zhang, Weifeng G., John L. Wilkin i Robert J. Chant. "Modeling the Pathways and Mean Dynamics of River Plume Dispersal in the New York Bight". Journal of Physical Oceanography 39, nr 5 (1.05.2009): 1167–83. http://dx.doi.org/10.1175/2008jpo4082.1.
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Abstract This study investigates the dispersal of the Hudson River outflow across the New York Bight and the adjacent inner- through midshelf region. Regional Ocean Modeling System (ROMS) simulations were used to examine the mean momentum dynamics; the freshwater dispersal pathways relevant to local biogeochemical processes; and the contribution from wind, remotely forced along-shelf current, tides, and the topographic control of the Hudson River shelf valley. The modeled surface currents showed many similarities to the surface currents measured by high-frequency radar [the Coastal Ocean Dynamics Applications Radar (CODAR)]. Analysis shows that geostrophic balance and Ekman transport dominate the mean surface momentum balance, with most of the geostrophic flow resulting from the large-scale shelf circulation and the rest being locally generated. Subsurface circulation is driven principally by the remotely forced along-shelf current, with the exception of a riverward water intrusion in the Hudson River shelf valley. The following three pathways by which freshwater is dispersed across the shelf were identified: (i) along the New Jersey coast, (ii) along the Long Island coast, and (iii) by a midshelf offshore pathway. Time series of the depth-integrated freshwater transport show strong seasonality in dispersal patterns: the New Jersey pathway dominates the winter–spring seasons when winds are downwelling favorable, while the midshelf pathway dominates summer months when winds are upwelling favorable. A series of reduced physics simulations identifies that wind is the major force for the spreading of freshwater to the mid- and outer shelf, that remotely forced along-shelf currents significantly influence the ultimate fate of the freshwater, and that the Hudson River shelf valley has a modest dynamic effect on the freshwater spreading.
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Kappes, Heike, i Peter Haase. "Slow, but steady: dispersal of freshwater molluscs". Aquatic Sciences 74, nr 1 (2.03.2011): 1–14. http://dx.doi.org/10.1007/s00027-011-0187-6.
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Mandrak, Nicholas E., i E. J. Crossman. "Postglacial dispersal of freshwater fishes into Ontario". Canadian Journal of Zoology 70, nr 11 (1.11.1992): 2247–59. http://dx.doi.org/10.1139/z92-302.
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The present-day distributions of 117 native freshwater fishes in Ontario have been shaped by processes active following the Wisconsinan glacial period, 80 000–10 000 years before present. During this glacial period, these species survived in unglaciated réfugia. To understand the processes that resulted in the recolonization of Ontario by fishes following the last glacial period, the refugial areas occupied by each species were determined using a refugial index, and glacial water bodies used as dispersal routes were identified. The refugial origins of the Ontario populations of 91 species were resolved. Seventy-two species resided in the Mississippian refugium, 13 species in the Atlantic Coastal refugium, 4 species in dual Atlantic Coastal – Mississippian refugia, 1 species in a Missourian refugium, and 1 species in Atlantic Coastal, Mississippian, and Missourian refugia. These conclusions differed significantly from those of other studies. Five general patterns were identified from the distributions of 104 species. In addition, there are 13 species that do not fit any of the general patterns. Most species with similar distributions in Ontario shared the same refugia and dispersal routes in eastern North America, therefore it is hypothesized that historical processes were important in shaping the present-day distributions of Ontario freshwater fishes.
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Kristiansen, Jørgen. "16. Dispersal of freshwater algae — a review". Hydrobiologia 336, nr 1-3 (październik 1996): 151–57. http://dx.doi.org/10.1007/bf00010829.
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Ditrich, Tomáš. "Dispersal and Migration Patterns of Freshwater Semiaquatic Bugs". Insects 12, nr 11 (28.10.2021): 976. http://dx.doi.org/10.3390/insects12110976.
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Semiaquatic bugs (Hemiptera: Heteroptera: Gerromorpha) are mostly wing-polymorphic species with flight dispersal as an important life history trait, but the specific flight ability and dispersal pattern remain unexplored in most species. This report presents the results of a long-term survey based on the individual marking of more than 23,000 specimens of eight water striders (Gerridae) and a water cricket Velia caprai (Veliidae). Three distinct lentic habitats were sampled (solitary fishponds, systems of nearby fishponds and systems of small, often temporary pools) and one lotic habitat—a small forest stream. Recaptures revealed that three gerrid species tend to stay at the breeding site, but can differ in dispersal via the water surface. Reproductive flightless females disperse most actively via the water surface, possibly bypassing the trade-off between dispersal and reproduction. One species has a sex-dependent dispersal pattern, with females being rather philopatric, whereas males often disperse. Three other gerrid species are highly dispersive and tend to change breeding site. V. caprai, the only lotic species included in this survey, tend to move upstream and possibly compensate for the downstream drift.
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Bernays, Sofie J., Daniel J. Schmidt, David A. Hurwood i Jane M. Hughes. "Phylogeography of two freshwater prawn species from far-northern Queensland". Marine and Freshwater Research 66, nr 3 (2015): 256. http://dx.doi.org/10.1071/mf14124.
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The distribution of a freshwater species is often dependent on its ability to disperse within the riverine system. Species with high dispersal abilities tend to be widespread, whereas those with restricted dispersal tend to be geographically restricted and are usually given higher conservation priority. Population structure was compared between a widespread freshwater prawn species, Macrobrachium australiense, and a narrow-range endemic freshwater prawn, Macrobrachium koombooloomba. The distribution of M. australiense and M. koombooloomba did not overlap, although suggested historical river-boundary rearrangements indicate that there has been the potential for dispersal into neighbouring catchments. A fragment of the mtDNA CO1 gene was analysed and a Mantel test revealed a significant isolation by distance effect for both species. Significant overall FST values confirmed that both species exhibited low levels of dispersal, a prediction for populations inhabiting a fragmented upland environment. The level of structure in M. australiense is surprising for a widely distributed species. Not all M. australiense populations conformed to the stream-hierarchy model, with results being best explained by historical river realignment or cross-catchment dispersal. The fact that both species show limited dispersal highlights the importance of conservation in highland areas for both endemic and widely spread species.
Rozprawy doktorskie na temat "Freshwater dispersal"
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Banha, Filipe Miguel Santos. "Human dispersal of freshwater invasive fauna". Doctoral thesis, Universidade de Évora, 2016. http://hdl.handle.net/10174/18152.
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The main goal of this thesis was to improve the knowledge on the mechanisms involved on Human dispersal of freshwater invasive fauna, contributing for the management of these problematic species. Several vectors were investigated, both accidental and intentional, from a freshwater invaders list that included some of the worse species. It was found that the red swamp crayfish and the signal crayfish presented desiccation survival capacities compatible with long-distance human-mediated dispersal. Off-road vehicles constituted a viable accidental vector for invasive macroinvertebrates, like the red swamp crayfish and the bladder snail. Live bait capture using dip nets and crayfish trapping constitute viable vectors for invasive freshwater macrofauna dispersal. The former is more related with accidental transport of small invasive organisms, and the latter is mostly related with intentional transport of invasive fish species. The importance of the angling web forums as a useful tool to help detection of non-native fish species was demonstrated with the first record of European Perch, a non-native fish in continental Portugal. Freshwater anglers from Portugal and Spain presented preference for invasive fish species, similar mobility, low incidence of live bait use and similar perception of biological freshwater invasions processes and impacts. Differences among countries were found for angler's activity patterns throughout the year and motivations for introductions. Zebra mussel larvae desiccation survival is compatible with long-distance overland dispersal. Its transport by natural vectors, like ducks, or human vectors like fishing tackle, such as waders and keep nets is viable. Yet, when comparing both types of vectors, fishing tackle presented a higher propensity to spread zebra mussel larvae than ducks; Dispersão de fauna invasiva dulçaquícola pelo Homem
Resumo:
O principal objetivo desta tese foi melhorar o conhecimento dos mecanismos envolvidos na dispersão de fauna dulçaquícola invasiva pelo homem, contribuindo assim para a gestão destas espécies problemáticas. Investigaram-se vários vetores, quer acidentais quer intencionais de uma lista de invasores dulçaquícolas que incluem algumas das piores espécies. Verificou-se que o lagostim vermelho e o lagostim sinal possuem uma capacidade de sobrevivência à dessecação compatível com a sua dispersão a longa distância pelo Homem. Os veículos todo-o-terreno constituem um vetor viável para macroinvertebrados invasivos como o lagostim vermelho e o caracol aquático. A captura de isco vivo com recurso a camaroeiro e o uso de armadilhas para a captura de lagostim constituem vetores viáveis de dispersão para a macrofauna dulçaquícola, sendo que o primeiro está relacionado com o transporte acidental de pequenos organismos invasores e o segundo com transporte intencional de peixes invasores. Através do primeiro registo em Portugal Continental de Perca-europeia, uma espécie não-nativa, demostrou-se a importância de fóruns on-line de pesca desportiva como uma ferramenta útil para a deteção de peixes não-nativos. Os pescadores dulçaquícolas de Portugal e Espanha apresentam preferência por espécies de peixes invasores, similar mobilidade, baixa incidência no uso de isco vivo e similar perceção dos processos e impactos das invasões biológicas dulçaquícolas. Detetaram-se diferenças entre países nos padrões de atividade dos pescadores durante o ano e na motivação para as introduções. A sobrevivência à dessecação de larvas de mexilhão-zebra é compatível com o seu transporte a longas distâncias fora de água, sendo viável o seu transporte quer por vetores naturais, como patos, quer humanos como equipamento de pesca, como botas altas e redes de retenção. No entanto, quando se comparam ambos os tipos de vetores, o equipamento de pesca apresenta maior propensão que os patos para dispersar larvas de mexilhão-zebra.
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Van, der Heyden Sophie. "Testing ubiquitous dispersal and freshwater/marine divergence in free-living protist groups". Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409856.
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Gillilland, Merritt Gale. "Dispersal ecology and control of the invasive land snail Cepaea nemoralis (L. 1758), from Ingham County, Michigan". Diss., Connect to online resource - MSU authorized users, 2006.
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Thesis (Ph. D.)--Michigan State University. Dept. of Zoology. Program in Ecology, Evolutionary Biology and Behavior, 2006.Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 161-168). Also issued in print.
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McGlashan, Dugald James, i piscador@hotmail com. "Consequences of Dispersal, Stream Structure and Earth History on Patterns of Allozyme and Mitochondrial DNA Variation of Three Species of Australian Freshwater Fish". Griffith University. Australian School of Environmental Studies, 2000. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030226.152217.
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Freshwater systems offer important opportunities to investigate the consequences of intrinsic biological and extrinsic environmental factors on the distribution of genetic variation, and hence population genetic structure. Drainages serve to isolate populations and so preserve historical imprints of population processes. Nevertheless, dispersal between and within drainages is important if the biology of the species confers a good dispersal capability. Knowledge of the population genetic structure or phylogeographic patterns of Australia's freshwater fish fauna is generally depauperate, and the present study aimed to increase this knowledge by investigating patterns of genetic diversity in three Australian species of freshwater fish. I was interested in the relative importance of dispersal capability, the hierarchical nature of stream structure and the consequences of earth history events on patterns of genetic diversity among populations. I examined three species from three families of Australian freshwater fish, Pseudomugil signifer (Pseudomugilidae), Craterocephalus stercusmuscarum (Atherinidae) and Hypseleotris compressa (Gobiidae). These species are abundant, have wide overlapping distributions and qualitatively different dispersal capabilities. I was interested in attempting to unravel how the biological, environmental and historical factors had served to influence the patterns and extent of genetic diversity within each species, thereby inferring some of the important evolutionary processes which have affected Australia's freshwater fauna. I used allozyme and 500-650bp sequences from the ATPase6 mitochondrial DNA (mtDNA) gene to quantify the patterns of genetic variation at several hierarchical levels: within populations, among populations within drainages and among drainages. I collected fish at several spatial scales, from species wide to multiple samples within drainages; samples were collected from the Northern Territory, Queensland and New South Wales. The species with the highest potential for dispersal, H. compressa, exhibited the lowest levels of genetic differentiation as measured at several allozyme loci (H. compressa: FST=0.014; P. signifer FST=0.58; C. stercusmuscarum FST=0.74). Populations of H. compressa also had low levels of mtDNA differentiation, with many recently derived haplotypes which were widespread along the coast of Queensland. This suggested either considerable gene flow occurs or recent demographic change in the populations sampled. As there was no relationship between geographic distance and genetic differentiation, the populations appeared to be out of genetic drift - gene flow equilibrium, assuming the two-dimensional stepping stone model of gene flow. Estimating contemporary gene flow was thus difficult. It was apparent that there has been a recent population expansion and / or contraction of H. compressa populations. It was concluded that there has been considerably more connectivity among populations of H. compressa in the recent past than either of the other study species. Populations of P. signifer showed considerable genetic subdivision at different hierarchical levels throughout the sampled range, indicating gene flow was restricted, especially between separate drainages. Two widely divergent regional groups which had high ATPase6 sequence divergence and approximately concordant patterns at allozyme loci were identified. Interestingly, the groups mirrored previous taxonomic designations. There was also significant subdivision among drainages within regional groups. For example, the adjacent Mulgrave-Russell and Johnstone drainages had individuals with haplotypes that were reciprocally monophyletic and had large allozyme frequency differences. This allowed me to examine the patterns of genetic differentiation among populations within drainages of two essentially independent, but geographically close systems. There was as much allozyme differentiation among populations within subcatchments as there was between subcatchments within drainages, and significant isolation by distance among all populations sampled within a drainage. This suggested that the estuarine confluence between subcatchments was not a barrier to P. signifer, but that distance was an important component in the determination of the distribution of genetic diversity within drainages in P. signifer. There were three main areas of investigation for C. stercusmuscarum: comparing upland and lowland streams of the drainages in north Queensland, investigating the consequences of eustasy on coastal margin populations and examining the intriguing distribution of the two putative sub species, C. s. stercusmuscarum and C. s. fulvus in south east Queensland. First, as populations in upland areas of east coast flowing rivers are above large discontinuities in the river profile, their occurrence is presumably the result of gene flow to and / or from lowland areas, or the result of invasions via the diversion of western flowing rivers. Concordant patterns at both genetic markers revealed that the latter possibility was the most likely, with fixed allozyme differences between upland and lowland populations, and large mtDNA sequence divergence. Indeed, it appeared that there may have been two independent invasions into the upland areas of rivers in North Queensland. Second, lowland east coast populations also had large, although not as pronounced, levels of population subdivision. Lack of isolation by distance, but with a concomitant high level of genetic differentiation among many comparisons, was consistent with a scenario of many small, isolated subpopulations over the range. Interestingly, widespread populations in central Queensland coastal populations (drainages which receive the lowest rainfall) were relatively genetically similar. This was consistent with the widest part of the continental shelf which at periods of lower sea level apparently formed a large interconnected drainage, illustrating the effect of eustatic changes on populations inhabiting a continental margin. Third, putative C. s. fulvus in lowland coastal Queensland drainages were genetically more similar to a population of C. s. fulvus collected from a tributary of the Murray-Darling (western flowing) than they were to adjacent putative C. s. stercusmuscarum. This implied that populations in south east Queensland, north to approximately the Burnett River, appeared to be derived from western flowing streams, and not via dispersal from other lowland east coast populations. Determining the relative importance of intrinsic and extrinsic factors to the development of population genetic structure is a difficult task. The present study demonstrated that the species with the highest dispersal potential had the lowest levels of genetic differentiation, waterfalls can limit gene flow, eustasy acts to join and separate populations leading to complex genetic patterns and that drainage rearrangements are important in determining the distribution of genetic diversity of populations now inhabiting isolated drainages. A difficulty with generalising about population genetic structure in obligate freshwater animals is the unique history of not only each drainage, but also the streams within that drainage and the idiosyncratic biological dynamics of the populations inhabiting those drainages.
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Cox, Andrea Joan. "Freshwater phylogeography, the impact of life history traits on the post-glacial dispersal of zooplankton in North America". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58330.pdf.
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Ullberg, Jörgen. "Dispersal in free-living, marine, benthic nematodes : passive or active processes?" Doctoral thesis, Stockholm University, Department of Zoology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-77.
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Meiofauna, and especially marine nematodes are common in sediments around the world. Despite very wide ranging distributions in many nematode species, little is presently known about their dispersal mechanisms shaping these patterns. Rafting, and perhaps ballast water transport has been suggested as viable means for nematode long-range transport. On a much smaller scale other processes have been suggested for their dispersal. They generally include some form of passive suspension into the water column and later on a passive, haphazard settling back towards the bottom.
Small-scale phenomena in nematode dispersal were studied by conducting a series of studies at Askö field station, Trosa Archipelago, Baltic proper. Studied aspects were one case of macrofaunal influence on nematode dispersal rate, using an amphipod, Monoporeia affinis as disturbing agent, and three different studies on mechanisms related to settling. The experiments were conducted both in laboratory and field settings.
The amphipod Monoporeia affinis did not exert any influence on the dispersal rate in the nematodes. The nematode dispersal was only an effect of time, in the aspect that the more time that past, the more nematodes dispersed from their place of origin. The settling experiments revealed that nematodes do have an active component in their settling behaviour, as they were able to exert influence on the spot where they were to settle. They were able to choose settling spot in response to the food quality of the sediment. It also became evident that contrary to common belief, nematodes are able to extend their presence in the water column far beyond the times that would be predicted considering settling velocities and hydrodynamic conditions alone.
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Zha, Yinghua. "Assembly of Gut Microbial Communities in Freshwater Fish and Their Roles in Fish Condition". Doctoral thesis, Uppsala universitet, Limnologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-314235.
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Animal hosts provide associated microorganisms with suitable ecological niches in their intestines. Microbes help their hosts to digest food, protect against pathogens, and influence the host’s metabolisms. Compositional variation of gut microbial communities is common among hosts, and may affect the health status of hosts. Diet and genetic factors are well known to influence the assembly of gut microbial communities. This thesis focuses on disentangling the contributions of factors including host genetics (sex), diet, environment, and other ecological processes to the assembly of gut microbial communities in freshwater fish. The association between gut microbial communities and fish condition is also evaluated in this thesis. Applying metacommunity theory, we found environmental factors including fish habitat, fish species, their diet, dispersal factors including microbes from fish diet, and ecological drift contributed to the assembly of fish gut microbial communities. The proportion of their contribution varied between fish species, where ecological drift explained more in perch than in roach. Under natural conditions fish populations face the risk of predation, which can induce competition and impose predation stress within prey individuals. This can therefore lead to changes in their diet qualities and quantities. In this thesis, it was shown that fish diet in terms of qualities and quantities significantly influenced the overall gut microbial composition, and this influence was dependent on fish sex, a host genetic factor. Predation stress was also suggested to significantly decrease the species richness. Furthermore, when fish were experiencing a diet shift, we showed that different bacterial phyla from novel food had different colonization success in the intestine, and this colonization success was positively influenced by predation stress. Fish condition was suggested in this thesis to be affected by gut microbial composition, especially by the contributions of the bacterial phyla Tenericutes and Actinobacteria.
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Vilmi, A. (Annika). "Assessing freshwater biodiversity:insights from different spatial contexts, taxonomic groups and response metrics". Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216669.
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Abstract Freshwater ecosystems are severely threatened by a variety of anthropogenic stressors. In order to keep track with at least part of the changes, it is important to efficiently assess and monitor freshwater biological diversity. Biological assessment programs are developed to detect human-induced changes in the ecological state of aquatic systems. These programs typically rely on the assumption that environmental conditions are the sole drivers of biological communities occupying a site and, thus, these local communities would correctly inform about environmental conditions. Recently, this background principle of current bioassessment methods has faced some criticism, stemming from the idea that community structuring is a more complex process than just a mere result of local environmental conditions. In this thesis, I studied the natural and anthropogenic drivers of freshwater biodiversity. I was particularly interested if the various biodiversity metrics studied showed any spatial patterns and if so, for which reasons these patterns might occur. To obtain a comprehensive picture of spatial patterns in biodiversity, I studied multiple spatial contexts, biological groups and indices. I found that environmental conditions were not the only drivers of freshwater biodiversity. Instead, different spatial patterns, likely stemming from dispersal processes, were surprisingly powerful drivers of aquatic communities and index values derived from them. The spatial context (i.e. spatial extent and connectivity) of the aquatic study systems likely played a major role in structuring biodiversity. I also found that the distinct biological groups and indices studied were partly related to different predictor variables. The findings of this thesis are of importance to the development of new bioassessment methods. The results of this thesis also suggest that the spatial context of the study setting should be acknowledged when interpreting results based on current bioassessment methodsTiivistelmä Makeanveden ekosysteemit ovat hyvin alttiita ihmistoiminnalle. Ekosysteemissä mahdollisesti tapahtuvien muutosten havaitseminen vaatii tehokkaita vesistöjen ekologisen tilan ja luonnon monimuotoisuuden arviointi- ja seurantamenetelmiä. Näiden menetelmien toimintaperiaatteen yleisenä tausta-ajatuksena on, että biologiset yhteisöt määräytyvät paikallisten ympäristöolojen mukaan. Tietyn paikan yhteisön oletetaan siis heijastavan kyseisen paikan ympäristön tilaa. Viime aikoina tausta-ajatus paikallisten ympäristöolojen merkityksestä ainoana eliöyhteisöjä muovaavana tekijänä on kuitenkin kohdannut kritiikkiä. Kriitikot painottavat, että biologisten yhteisöjen rakenteeseen vaikuttavat monet muutkin asiat kuin paikalliset ympäristöolosuhteet ja niissä tapahtuvat ihmisperäiset muutokset. Väitöskirjassani tutkin sisävesien luonnon monimuotoisuuteen vaikuttavia tekijöitä. Olin erityisen kiinnostunut siitä, näkyykö tutkituissa biologisissa parametreissa maantieteellisessä tilassa ilmeneviä spatiaalisia säännönmukaisuuksia. Saadakseni mahdollisimman laaja-alaisen käsityksen luonnon monimuotoisuudessa esiintyvistä spatiaalisista säännönmukaisuuksista, tutkin useaa spatiaalista kontekstia, eliöryhmää ja indeksiä. Tutkimuksessa selvisi, että paikalliset ympäristöolosuhteet eivät ole ainoita luonnon monimuotoisuuteen vaikuttavia tekijöitä. Erilaiset spatiaaliset säännönmukaisuudet, todennäköisesti eliöiden levittäytymiseen liittyvien seikkojen aiheuttamina, olivat yllättävän yleisiä makeiden vesien eliöyhteisöjen rakenteessa ja niihin perustuvien indeksien arvoissa. Tutkimussysteemien spatiaalinen konteksti (alueen laajuus ja paikkojen väliset spatiaaliset suhteet) selvästi vaikutti luonnon monimuotoisuutta kuvastavien indeksien arvojen vaihteluun. Lisäksi selvisi, että eri eliöryhmät ja indeksit olivat useimmiten liitoksissa hyvin erilaisiin selittäviin muuttujiin, osoittaen, että nämä mittarit kuvastavat eri asioita. Väitöskirjassa esitetyt havainnot on tärkeää huomioida vesistöjen ekologisen tilan ja luonnon monimuotoisuuden arviointi- ja seurantamenetelmiä kehitettäessä. Spatiaalisen kontekstin merkitys olisi hyvä huomioida myös nykyisten arviointi- ja seurantamenetelmien tuottamien tulosten tulkinnassa
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Hunter, Brena Elese. "Population genetic structure and patterns of dispersal in the Giant Long-Armed Prawn, Macrobrachium lar (Fabricius, 1798) (Decapoda : Palaemonidae)". Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46131/1/Brena_Hunter_Thesis.pdf.
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The Giant Long-Armed Prawn, Macrobrachium lar is a freshwater species native to the Indo-Pacific. M. lar has a long-lived, passive, pelagic marine larval stage where larvae need to colonise freshwater within three months to complete their development. Dispersal is likely to be influenced by the extensive distances larvae must transit between small oceanic islands to find suitable freshwater habitat, and by prevailing east to west wind and ocean currents in the southern Pacific Ocean. Thus, both intrinsic and extrinsic factors are likely to influence wild population structure in this species.
The present study sought to define the contemporary broad and fine-scale population genetic structure of Macrobrachium lar in the south-western Pacific Ocean. Three polymorphic microsatellite loci were used to assess patterns of genetic variation within and among 19 wild adult sample sites. Statistical procedures that partition variation implied that at both spatial scales, essentially all variation was present within sample sites and differentiation among sites was low. Any differentiation observed also was not correlated with geographical distance. Statistical approaches that measure genetic distance, at the broad-scale, showed that all south-western Pacific Islands were essentially homogeneous, with the exception of a well supported divergent Cook Islands group. These findings are likely the result of some combination of factors that may include the potential for allelic homoplasy, through to the effects of sampling regime. Based on the findings, there is most likely a divergent M. lar Cook Islands clade in the south-western Pacific Ocean, resulting from prevailing ocean currents. Confirmation of this pattern will require a more detailed analysis of nDNA variation using a larger number of loci and, where possible, use of larger population sizes.
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McGlashan, Dugald James. "Consequences of Dispersal, Stream Structure and Earth History on Patterns of Allozyme and Mitochondrial DNA Variation of Three Species of Australian Freshwater Fish". Thesis, Griffith University, 2000. http://hdl.handle.net/10072/366647.
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Freshwater systems offer important opportunities to investigate the consequences of intrinsic biological and extrinsic environmental factors on the distribution of genetic variation, and hence population genetic structure. Drainages serve to isolate populations and so preserve historical imprints of population processes. Nevertheless, dispersal between and within drainages is important if the biology of the species confers a good dispersal capability. Knowledge of the population genetic structure or phylogeographic patterns of Australia's freshwater fish fauna is generally depauperate, and the present study aimed to increase this knowledge by investigating patterns of genetic diversity in three Australian species of freshwater fish. I was interested in the relative importance of dispersal capability, the hierarchical nature of stream structure and the consequences of earth history events on patterns of genetic diversity among populations. I examined three species from three families of Australian freshwater fish, Pseudomugil signifer (Pseudomugilidae), Craterocephalus stercusmuscarum (Atherinidae) and Hypseleotris compressa (Gobiidae). These species are abundant, have wide overlapping distributions and qualitatively different dispersal capabilities. I was interested in attempting to unravel how the biological, environmental and historical factors had served to influence the patterns and extent of genetic diversity within each species, thereby inferring some of the important evolutionary processes which have affected Australia's freshwater fauna. I used allozyme and 500-650bp sequences from the ATPase6 mitochondrial DNA (mtDNA) gene to quantify the patterns of genetic variation at several hierarchical levels: within populations, among populations within drainages and among drainages. I collected fish at several spatial scales, from species wide to multiple samples within drainages; samples were collected from the Northern Territory, Queensland and New South Wales. The species with the highest potential for dispersal, H. compressa, exhibited the lowest levels of genetic differentiation as measured at several allozyme loci (H. compressa: FST=0.014; P. signifer FST=0.58; C. stercusmuscarum FST=0.74). Populations of H. compressa also had low levels of mtDNA differentiation, with many recently derived haplotypes which were widespread along the coast of Queensland. This suggested either considerable gene flow occurs or recent demographic change in the populations sampled. As there was no relationship between geographic distance and genetic differentiation, the populations appeared to be out of genetic drift - gene flow equilibrium, assuming the two-dimensional stepping stone model of gene flow. Estimating contemporary gene flow was thus difficult. It was apparent that there has been a recent population expansion and / or contraction of H. compressa populations. It was concluded that there has been considerably more connectivity among populations of H. compressa in the recent past than either of the other study species. Populations of P. signifer showed considerable genetic subdivision at different hierarchical levels throughout the sampled range, indicating gene flow was restricted, especially between separate drainages. Two widely divergent regional groups which had high ATPase6 sequence divergence and approximately concordant patterns at allozyme loci were identified. Interestingly, the groups mirrored previous taxonomic designations. There was also significant subdivision among drainages within regional groups. For example, the adjacent Mulgrave-Russell and Johnstone drainages had individuals with haplotypes that were reciprocally monophyletic and had large allozyme frequency differences. This allowed me to examine the patterns of genetic differentiation among populations within drainages of two essentially independent, but geographically close systems. There was as much allozyme differentiation among populations within subcatchments as there was between subcatchments within drainages, and significant isolation by distance among all populations sampled within a drainage. This suggested that the estuarine confluence between subcatchments was not a barrier to P. signifer, but that distance was an important component in the determination of the distribution of genetic diversity within drainages in P. signifer. There were three main areas of investigation for C. stercusmuscarum: comparing upland and lowland streams of the drainages in north Queensland, investigating the consequences of eustasy on coastal margin populations and examining the intriguing distribution of the two putative sub species, C. s. stercusmuscarum and C. s. fulvus in south east Queensland. First, as populations in upland areas of east coast flowing rivers are above large discontinuities in the river profile, their occurrence is presumably the result of gene flow to and / or from lowland areas, or the result of invasions via the diversion of western flowing rivers. Concordant patterns at both genetic markers revealed that the latter possibility was the most likely, with fixed allozyme differences between upland and lowland populations, and large mtDNA sequence divergence. Indeed, it appeared that there may have been two independent invasions into the upland areas of rivers in North Queensland. Second, lowland east coast populations also had large, although not as pronounced, levels of population subdivision. Lack of isolation by distance, but with a concomitant high level of genetic differentiation among many comparisons, was consistent with a scenario of many small, isolated subpopulations over the range. Interestingly, widespread populations in central Queensland coastal populations (drainages which receive the lowest rainfall) were relatively genetically similar. This was consistent with the widest part of the continental shelf which at periods of lower sea level apparently formed a large interconnected drainage, illustrating the effect of eustatic changes on populations inhabiting a continental margin. Third, putative C. s. fulvus in lowland coastal Queensland drainages were genetically more similar to a population of C. s. fulvus collected from a tributary of the Murray-Darling (western flowing) than they were to adjacent putative C. s. stercusmuscarum. This implied that populations in south east Queensland, north to approximately the Burnett River, appeared to be derived from western flowing streams, and not via dispersal from other lowland east coast populations. Determining the relative importance of intrinsic and extrinsic factors to the development of population genetic structure is a difficult task. The present study demonstrated that the species with the highest dispersal potential had the lowest levels of genetic differentiation, waterfalls can limit gene flow, eustasy acts to join and separate populations leading to complex genetic patterns and that drainage rearrangements are important in determining the distribution of genetic diversity of populations now inhabiting isolated drainages. A difficulty with generalising about population genetic structure in obligate freshwater animals is the unique history of not only each drainage, but also the streams within that drainage and the idiosyncratic biological dynamics of the populations inhabiting those drainages.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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Książki na temat "Freshwater dispersal"
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Zoogeography of fresh waters. Wiesbaden: AULA-Verlag, 1990.
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Bănărescu, Petru. Zoogeography of fresh waters. Wiesbaden: AULA-Verlag, 1990.
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Bănărescu, Petru. Zoogeography of fresh waters. Wiesbaden: AULA-Verlag, 1990.
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Bagur, Daniel. Where the fish are: A science-based guide to stalking freshwater fish. New York: McGraw-Hill, 2009.
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Where the Fish Are. New York: McGraw-Hill, 2009.
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New Zealand Freshwater Fishes An Historical And Ecological Biogeography. Springer, 2010.
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Hughes, Jocelyne, red. Freshwater Ecology and Conservation. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198766384.001.0001.
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This practical manual of freshwater ecology and conservation provides a state-of-the-art review of the methods and techniques used to measure, monitor, and conserve freshwater ecosystems. It offers a single, comprehensive, and accessible synthesis of the vast amount of technical literature for freshwater ecology and conservation that is currently dispersed in manuals, toolkits, journals, handbooks, ‘grey’ literature, and websites. Successful conservation outcomes are ultimately built on a sound ecological framework in which every species must be assessed and understood at the individual, community, and catchment level of interaction. For example, freshwater ecologists need to understand hydrochemical storages and fluxes, the physical systems influencing freshwaters at the catchment and landscape scale, and the hydrochemical processes that maintain species assemblages and their dynamics. A thorough understanding of all these varied processes, and the techniques for studying them, is essential for the effective conservation and management of freshwater ecosystems. Primarily aimed at graduate students and established researchers in the fields of freshwater ecology and conservation biology, this book is also a valuable reference for conservation practitioners, aquatic managers, and professional limnologists worldwide.
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Kirchman, David L. Community structure of microbes in natural environments. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0004.
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Community structure refers to the taxonomic types of microbes and their relative abundance in an environment. This chapter focuses on bacteria with a few words about fungi; protists and viruses are discussed in Chapters 9 and 10. Traditional methods for identifying microbes rely on biochemical testing of phenotype observable in the laboratory. Even for cultivated microbes and larger organisms, the traditional, phenotype approach has been replaced by comparing sequences of specific genes, those for 16S rRNA (archaea and bacteria) or 18S rRNA (microbial eukaryotes). Cultivation-independent approaches based on 16S rRNA gene sequencing have revealed that natural microbial communities have a few abundant types and many rare ones. These organisms differ substantially from those that can be grown in the laboratory using cultivation-dependent approaches. The abundant types of microbes found in soils, freshwater lakes, and oceans all differ. Once thought to be confined to extreme habitats, Archaea are now known to occur everywhere, but are particularly abundant in the deep ocean, where they make up as much as 50% of the total microbial abundance. Dispersal of bacteria and other small microbes is thought to be easy, leading to the Bass Becking hypothesis that “everything is everywhere, but the environment selects.” Among several factors known to affect community structure, salinity and temperature are very important, as is pH especially in soils. In addition to bottom-up factors, both top-down factors, grazing and viral lysis, also shape community structure. According to the Kill the Winner hypothesis, viruses select for fast-growing types, allowing slower growing defensive specialists to survive. Cultivation-independent approaches indicate that fungi are more diverse than previously appreciated, but they are less diverse than bacteria, especially in aquatic habitats. The community structure of fungi is affected by many of the same factors shaping bacterial community structure, but the dispersal of fungi is more limited than that of bacteria. The chapter ends with a discussion about the relationship between community structure and biogeochemical processes. The value of community structure information varies with the process and the degree of metabolic redundancy among the community members for the process.
Części książek na temat "Freshwater dispersal"
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Ptatscheck, Christoph, i Birgit Gansfort. "Dispersal of free-living nematodes." W Ecology of freshwater nematodes, 151–84. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0005.
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Abstract This chapter considers the possible reasons underlying the ubiquity of nematodes and their high abundances in nearly all of their habitats. It discusses three phases of dispersal. The first section considers the drivers and mechanisms of the emigration of nematodes from their original habitat. The second section outlines active and passive modes of transfer and provides estimates of transfer distances. In the last section, immigration is addressed, including an overview of the density and species composition in developing nematode communities during colonization.
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Kristiansen, Jørgen. "Dispersal of freshwater algae — a review". W Biogeography of Freshwater Algae, 151–57. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-0908-8_15.
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Majdi, Nabil, i Walter Traunspurger. "Introduction to freshwater nematodes in ecology: current knowledge and research." W Ecology of freshwater nematodes, 1–30. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0001.
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Abstract This chapter provides information on nematode morphology and reproduction; role of nematodes in freshwater ecosystems; and distribution and dispersal of free-living nematodes and their role in food webs.
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McDowall, R. M. "A Biogeographical Synthesis 3: Issues of Diadromy, Diversification and Dispersal". W New Zealand Freshwater Fishes, 375–97. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9271-7_18.
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Wooster, D. E., A. Sih i G. Englund. "Prey dispersal and predator impacts on stream benthic prey". W Evolutionary Ecology of Freshwater Animals, 89–116. Basel: Birkhäuser Basel, 1997. http://dx.doi.org/10.1007/978-3-0348-8880-6_4.
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Kennett, R., i Jeremy Russell-Smith. "Seed dispersal by freshwater turtles in northern Australia". W Herpetology in Australia, 69–70. P.O. Box 20, Mosman NSW 2088, Australia: Royal Zoological Society of New South Wales, 1993. http://dx.doi.org/10.7882/rzsnsw.1993.012.
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Melo, Martim, Luis M. P. Ceríaco i Rayna C. Bell. "Biogeography and Evolution in the Oceanic Islands of the Gulf of Guinea". W Biodiversity of the Gulf of Guinea Oceanic Islands, 141–70. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-06153-0_6.
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AbstractAs with most archipelagos, geography played a central role in the assembly and evolution of the endemic-rich biological communities of the Gulf of Guinea oceanic islands. The islands are located at moderate distances from the species-rich African continent that surrounds them to the east and north. This proximity facilitated colonization by many branches of the tree of life, but gene flow between the islands and continent was low enough that many lineages evolved in isolation once they reached the archipelago, resulting in many endemic species. Furthermore, several of the island taxa belong to groups typically considered to be “poor dispersers” across sea barriers, which strongly supports a role for natural rafts in seeding the islands. Oceanic currents, including the freshwater pathways that extend from large river drainages into the Gulf of Guinea during the rainy season, also support this hypothesis. The distances between the islands are equivalent to those between the islands and the continent such that inter-island dispersal events appear to be relatively rare and thus few taxa are shared between them. Still, the islands present multiple cases of secondary contact leading to hybridization and genetic introgression between closely related lineages—providing several models to study the role and consequences of gene flow in evolution. Most taxa for which molecular estimates of divergence time have been derived are much younger than the ages of the islands. This pattern is consistent with high species turnover, likely resulting from a combination of small island sizes, proximity to the African continent and a long history of intense volcanic activity. The Gulf of Guinea oceanic islands provide multiple examples of classical adaptations to island life (the “island syndrome”), including giants and dwarves, ornament and color loss, among others. In addition, emerging studies of birds are highlighting the importance of competition regimes in driving phenotypic change—with examples of both character release (low inter-specific competition) and character displacement (inter-specific competition upon secondary contact). Collectively, the Gulf of Guinea oceanic islands offer unique opportunities to study adaptation and speciation in a range of taxa and contexts.
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Strayer, David L. "Dispersal". W Freshwater Mussel Ecology, 24–41. University of California Press, 2008. http://dx.doi.org/10.1525/california/9780520255265.003.0003.
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"Freshwater Fisheries in Canada: Historical and Contemporary Perspectives on the Resources and Their Management". W Freshwater Fisheries in Canada: Historical and Contemporary Perspectives on the Resources and Their Management, redaktorzy Nicholas E. Mandrak, R. Allen Curry, Pierre Dumont, James D. Reist, Eric B. Taylor i Douglas A. Watkinson. American Fisheries Society, 2023. http://dx.doi.org/10.47886/9781934874707.ch1.
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Abstract.—Currently, there are 201 native species and 21 established nonnative fish species known from the freshwaters in Canada compared to 44 species reported in the year 1700. This increase is the result of increasing exploration and sampling, evolving fish systematics, and the introduction of nonnative species. Contemporary patterns of native freshwater fish distributions in Canada have been profoundly influenced by postglacial dispersal from unglaciated refugia following the Wisconsinan Glacial Event. This chapter reviews the composition, origin, and distributional patterns of freshwater fishes nationally and regionally in Canada. The Mississippian refugium (119 species) was by far the greatest source of freshwater fish species now occurring in Canada, followed by the Atlantic coastal (59 species), Pacific (42), Missourian (26), and Beringian (17) refugia. The Laurentian Great Lakes drainage (149 species) has the greatest number of freshwater fish species, followed by the St. Lawrence (125), Western Hudson Bay (107), and Pacific (74) basins. Following the postglacial colonization of Canada, climate became a major driver of native species richness and, most recently, anthropogenic pressures have become drivers of nonnative species richness. The number of Canadian freshwater fish species will undoubtedly change not only as a result of a better understanding of fish phylogeny at the molecular level, but also as a result of the ongoing introduction of nonnative species into Canadian waters and loss of endangered species, both likely to be exacerbated under climate change.
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Hogg, Ian D., John M. Eadie i Yves de Lafontaine. "Passive Dispersal Among Fragmented Habitats: The Population Genetic Consequences for Freshwater and Estuarine Amphipods". W Crustaceans and the Biodiversity Crisis, 307–26. BRILL, 1999. http://dx.doi.org/10.1163/9789004630543_025.
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Ditrich, Tomas. "Migration and dispersal patterns of semiaquatic bugs from lentic and lotic freshwater habitats". W 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.95171.
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Hormozi, S., B. Firoozabadi i H. Ghasvari Jahromi. "3-D Simulation of Sedimentation in Turbidity Currents". W ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43584.
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The gravity currents on the inclined boundaries are formed when the inflow fluid has a density difference with the ambient fluid and a tangential component of gravity becomes the driving force. If the density difference arises from the suspended particles, the currents are known as particle-laden density currents, or turbidity currents in which the local density depends on the concentration of particles. A low Reynolds k-ε turbulent model is used to simulate three dimensional turbidity currents. Also some laboratory tests were conducted to study the 3D flow resulting from the release of particle laden density currents on a sloping surface in a channel of freshwater via a sluice gate. Kaolin was used as the suspended material. The height, width, velocity and concentration profiles of turbidity currents were calculated and compared with the experimental data and showed good agreement. Different settling velocity formulas based on, first, solitary particle and, second, considering the effect of dispersed particles thorough the fluid are exerted in the concentration equation and the results compare with each other. Also the sedimentation heights of the turbidity current are simulated which are compatible with the experimental data.
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Zubair, Muhammad, i Aman Ullah. "Chicken Feathers Keratin/ Modified Graphene Oxide Based Biosorbent for Water Remediation". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/xygc9438.
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Water is one of the most precious resources on the earth and is a life source for all the living organisms. Around 75% of industrial wastewater is being discharged into the freshwater streams and 38% of it released untreated. Worldwide, wastewater from oil sands projects is being released into the water bodies and severely polluting the water resources. The tailings pond water contains toxic metals including lead, cadmium, arsenic, nickel, chromium, and selenium. Reverse osmosis, filtration and disinfection are being used to address the water quality issues. However, these have high cost, shorter life and poor adsorption capacity. We developed an eco-friendly biosorbent from chicken feathers with potential to remove heavy metals. Keratin from chicken feathers is an almost infinite source of natural protein ( >92%). Poultry feathers have a few applications, but large quantities are disposed in landfills that create environmental issues. Chicken feathers were washed, ground, and dissolved using reducing agent. Keratin was isolated from the solution using dialysis followed by freeze drying. Finally, biosorbent was obtained by treating powdered keratin with water dispersed modified graphene oxide and polymerized at high temperature. The biosorbents was tested for metals removal from synthetic contaminated water with concentration of 600, 1000 and 2000 ppb. Adsorption studies were performed using ICP-MS and compared with the commercially available adsorbents. Our study revealed that adsorbent can remove As, Se, Pb, Cu, Cd and Cr with adsorption capacity between 80-99% from the polluted water. This excellent adsorption capacity was ascribed to the incorporation of graphene oxide which increased the surface affinity of the keratin to adsorb heavy metals easily. The synthesis of environmentally benign adsorbent from chicken feathers showed potential to be implemented on larger scale. The study will also provide an alternate for chicken feathers utilization instead of simple disposal that causes environmental concerns.
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Schindler, Rob, Sean Comber i Andrew Manning. "METAL POLLUTANT PATHWAYS IN COHESIVE COASTAL CATCHMENTS: INFLUENCE OF FLOCCULATION ON PARTITIONING AND FLUX". W GEOLINKS International Conference. SAIMA Consult Ltd, 2020. http://dx.doi.org/10.32008/geolinks2020/b2/v2/09.
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Potentially toxic metals (PTMs) dispersed within catchments from land-based sources pose serious, long-term threats to aquatic ecology and human health. Their chemical state or form affects the potential for transportation and bioavailability and ultimate environmental fate. PTMs are transported either as (1) particulates adsorbed onto sediments, or 2) solutes in groundwater and open channel flow. Cohesive sediment occupies a major part of the world’s coastlines. PTMs are readily sorbed onto clay/silt and consequently particulate-borne PTMs dominate in estuaries and coastal waters. Sediments also represent a considerable ‘sink’ of contaminants which can be periodically remobilized. The role of suspended particulates in the uptake, release, and transport of heavy metals is thus a crucial link in understanding PTM dispersion in these environments. Cohesive sediment is subject to flocculation which dictates the behaviour of suspended sediment. PTM partitioning, flocculation and particulate-borne PTM dynamics are spatially and temporally variable in response to a complex array of inter-related physical and chemical factors exhibited within tidal catchments. However, knowledge of the dispersion and accumulation of both particulate and soluble forms of PTMs within cohesive coastal catchments is limited by little understanding of the association of PTMs with flocculated sediments and their subsequent deposition. This study investigates the influence of changing hydrodynamics and salinities to reveal the partitioning coefficients (Kp) and PTM settling flux (PTMSF) for different spatial and temporal locations within an idealized mesotidal catchment. The data show that the ratio of soluble and particulate-borne PTMs are dependent on salinity and flocculation, and that PTMSF is dependent upon partitioning and flocculation dynamics. Kp is largely dictated by salinity, but floc size and suspended particulate matter concentration (SPMC) are also influential, particular for PTMs with low chloride complexation and in freshwater. PTMSF is a function of Kp, floc size and settling velocity and varies by up to 3 orders of magnitude in response to changing environmental conditions. Findings will improve our ability to predict and monitor contaminant transport for PTMs generated by industries such as agriculture, mining, fisheries, aquaculture & marine engineers. They can be incorporated in existing decision making tools, and help improve numerical modelling parameteristion, to maintain environmental quality standards and limit the impacts of bioavailability of metals in aquatic environment.
Raporty organizacyjne na temat "Freshwater dispersal"
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Mahadevan, Amala. Early Student Support for Process Studies of Surface Freshwater Dispersal. Fort Belvoir, VA: Defense Technical Information Center, wrzesień 2013. http://dx.doi.org/10.21236/ada598804.
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Pokrzywinski, Kaytee, Kaitlin Volk, Taylor Rycroft, Susie Wood, Tim Davis i Jim Lazorchak. Aligning research and monitoring priorities for benthic cyanobacteria and cyanotoxins : a workshop summary. Engineer Research and Development Center (U.S.), sierpień 2021. http://dx.doi.org/10.21079/11681/41680.
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In 2018, the US Army Engineer Research and Development Center partnered with the US Army Corps of Engineers–Buffalo District, the US Environmental Protection Agency, Bowling Green State University, and the Cawthron Institute to host a workshop focused on benthic and sediment-associated cyanobacteria and cyanotoxins, particularly in the context of harmful algal blooms (HAB). Technical sessions on the ecology of benthic cyanobacteria in lakes and rivers; monitoring of cyanobacteria and cyanotoxins; detection of benthic and sediment-bound cyanotoxins; and the fate, transport, and health risks of cyanobacteria and their associated toxins were presented. Research summaries included the buoyancy and dispersal of benthic freshwater cyanobacteria mats, the fate and quantification of cyanotoxins in lake sediments, and spatial and temporal variation of toxins in streams. In addition, summaries of remote sensing methods, omic techniques, and field sampling techniques were presented. Critical research gaps identified from this workshop include (1) ecology of benthic cyanobacteria, (2) identity, fate, transport, and risk of cyanotoxins produced by benthic cyanobacteria, (3) standardized sampling and analysis protocols, and (4) increased technical cooperation between government, academia, industry, nonprofit organizations, and other stakeholders. Conclusions from this workshop can inform monitoring and management efforts for benthic cyanobacteria and their associated toxins.