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1
She, Nian. "Chaos in aquatic systems /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/6370.
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Johansson, Håkan. "On Distribution Coefficients in Aquatic Systems." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1777.
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In this thesis, different types of chemical and physical distribution coefficients are identified, examined and used to describe the fate and transport pathways of substances in aquatic systems.
Observations from field experiments in streams with non-reactive and reactive tracers constituted the basis for development of an advection-dispersion model. Differences in the concentrations in both the water and sediment data for the tracers were due to the particle affinity of the reactive tracer. This difference in behaviour could be described by including an instantanous and a kinetically controlled sorption, which included distribution coefficients, in the water column (Kd) and in the streambed sediment (KB), respectively.
The results presented in this thesis also include a model for the lake characteristic concentration of suspended particulate matter (SPM). The SPM-model can be used to describe mass flows of particles in lakes. The traditional distribution (or partition) coefficient Kd has been found to be unsuitable for interpretations of the particle association of solutes and also for distributing solute mass flows. Instead, the particulate or the dissolved fraction, PF and DF, defined as ratios of the particulate or dissolved concentration to the total concentration respectively, is recommended for mass-balance calculations. A new PF-model for phosphorus has meant that this part is no longer the most sensitive part of predicting concentrations of phosphorus in lakes using a more extensive dynamic model.
New methods have also been developed to describe the shape of lakes. Together with the mixing depth of lakes, the shape of a lake can be transformed into a distribution coefficient that physically determines the portion of a lake that is exposed, both areally and vertically, to continuously mixing.
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Johansson, Håkan. "On distribution coefficients in aquatic systems /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5245-0/.
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Pers, B. Charlotta. "Modelling organic matter dynamics in aquatic systems /." Linköping : Univ, 2000. http://www.bibl.liu.se/liupubl/disp/disp2000/arts214s.htm.
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Al-Jubouri, Q. S. "Automatic computer vision systems for aquatic research." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3009695/.
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Recently, there has been an increase in biological research interest in fish, and zebrafish, as an efficient model in the investigation of a broad range of human diseases and genetic studies. Economically, the enormous number, low price and limited maintenance requirements of this fish species encouraged the researchers to use it extensively. The larva of this animal is also considered to be promising subjects for research that is not subject to same strict legal requirements as the adult fish. The importance of this animal in research has increased the demand for developing new computer vision tools and methods that could help researchers to perform more related investigations as well as understand behaviour for different experimental tests. Computer vision is an efficient, economical and non-intrusive tool that can be applied to research in aquatic laboratories and aquaculture environments. However, in marine applications, this technology is still facing big challenges due to the free-swimming nature and unpredictable behaviour of the fish. This thesis presents a suite of novel and cost-effective tools for fish tracking and behavioural analysis, sizing, and identification of individual zebrafish. These main contributions this work is outlined briefly as follows. The first part of this work deals with stimulation and physical activity analysis for fish larvae, a novel robust and automated multiple fish larva tracking system is proposed. The system is capable of tracking twenty-five fish larvae simultaneously and extracting all physical activity parameters such as; speed, acceleration, path, moved distance and active time. The system is used for further studies throughout local occurrence behaviour recognition and studying the behavioural of the fish larvae following electrical, chemical and thermal stimulation. The proposed tracking system has been adopted in the biologists' aquatic laboratory to be used as a robust tool for fish behaviour analysis when fish are exposed to several types of stimulation. In the second part of the work, two novel practical and cost-effective models; orthogonal and stereo systems are designed and implemented to estimate the length of small free-swimming fish using off-the-shelf-components. The designed models are accurate and easy to adapt use for small experimental tanks in laboratory settings. The models have been thoroughly tested and validated experimentally. The third part of this thesis offers novel non-contact methods for recognition of individual free-swimming fish. Such systems can significantly reduce experts efforts and time required for fish tagging process and also offer a real-time recognition technique that can be alternative to the existing tagging methods used in this field. Through the purposes of this suite of novel computer vision tools and models, this thesis has provided successful solutions for behavioural analysis, fish sizing, individual fish recognition related research problems. The proposed solutions addressed major research problems and provided novel and cost-effective solutions for these problems.
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Wollenberg, Jennifer Lee. "Factors affecting mercury emission from aquatic systems." Diss., [Free access to full dissertation available to Lehigh users only.], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3358118.
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Holland, Angela. "BRIDGING AQUATIC AND TERRESTRIAL ECOSYSTEMS: ECOLOGY OF SEMI-AQUATIC MAMMALS IN SOUTHERN ILLINOIS." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1269.
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Mammals in freshwater aquatic systems play important roles as ecosystem engineers, trophic transfer agents, and apex predators, thus acting as indicators of freshwater ecosystem function. Watersheds inhabited by semi-aquatic mammals have increased links between adjacent terrestrial and aquatic ecosystems compared to watersheds where they are not present. Semi-aquatic mammals not only exert top-down influences on streams, but are affected by bottom-up forces from the riparian system itself. The goal of this study was to identify variables that correlate with the presence of beaver (Castor canadensis), muskrat (Ondatra zibethicus), mink (Neovison vison), and river otter (Lontra canadensis), including their interactions, resulting in a better understanding of the areas where these semi-aquatic mammals occur and their effects on the riparian system. The objectives of this study were (1) to identify variables related to the probability of detection, initial occupancy, colonization, and extinction of the 4 semi-aquatic mammals in southern Illinois; and (2) to test if the reintroduction of river otter has changed stream food webs. To address my first objective, I sampled 120 bridge sites in 2 periods (winter: Jan-Feb; and spring: Mar-Apr) during 2012–2014 in 11 major watersheds in the southern third of Illinois (44,526 km2) to estimate multi-season occupancy. Each survey unit was a 400-m stream segment visited twice by 2 observers for a total of 4 observations per site per period. Observers recorded all mammal signs found, including sign species and type. Sites were Intensive Basin Survey Sites sampled by Illinois Department of Natural Resources (IDNR) and Illinois Environmental Protection Agency (IEPA), allowing data collected by the state to be available for explanatory variables for mammal occupancy. Data collected by the Illinois Natural History Survey (INHS) also were available for a subset of sites. I collected local- and landscape-scale habitat and weather variables for each site. I developed hypotheses regarding occupancy of sites based on land-cover, human disturbance, and stream attributes for each species. I developed additional hypotheses regarding prey availability and water quality for river otter and mink. Sites used in each analysis were dependent on data available to address the hypotheses of interest. Beaver and muskrat were present at ≥100 of 103 sites for ≥1 observation. Naïve occupancy was high (≥82%) every year for both species. Detection probabilities for beaver and muskrat were best predicted by survey period. Beaver detection remained fairly constant across survey periods except for a decrease in winter 2014, whereas muskrat detection was generally lower during winter and higher during spring. Beaver were more likely to occupy larger streams than smaller streams during the initial survey period. Sites that lacked a dominant land-cover had a lower probability of beaver colonization than sites dominated by agriculture or woody vegetation at the landscape scale. In addition, the probability that a site would be colonized by beaver during the study increased with availability of water within 1 km of the surveyed segment, increased stream density, sites at larger streams, and river otter presence during the previous period. The probability of site extinction decreased as stream size, stream density within 1 km, and water availability within 500 m of the survey segment increased. Occupancy of muskrat during the initial survey period was negatively predicted by % forest in the 1-km riparian area, channel incision, and amount mercury in the sediment. Colonization by muskrats was lower during the long spring to winter intervals than the short winter to spring intervals, and was positively related to the amount of organic carbon in the sediment. The probability of site extinction by muskrat increased with increasing % forest within the riparian area around the stream segment, decreasing 1-km stream density, and when land-cover within 1 km of sites was dominated by agriculture or woody vegetation. Multi-season occupancy of river otter and mink were assessed in 2 separate analyses that used either land-cover and management variables or prey availability and riparian community composition, respectively. In the first analysis, river otter and mink were present at ≥84 of 103 sites. Naïve occupancy was higher every year for mink (≥88.3%) than for river otter (≥55.3%). Detection of river otter and mink in the first analysis increased as substrate availability increased. Occupancy of river otter during the initial survey period was predicted by large stream size, low % developed area within 250 m of the surveyed segment, and proximity to nearest river otter reintroduction point. Probability of colonization by river otter varied by survey period and was higher at sites with larger streams, higher stream density, lower % developed area, and within a known river otter population area. Site extinction by river otter in the first analysis varied by survey period and was linked to increased organic carbon in the sediment, and decreased road density within 1 km of the surveyed segment. River otter harvest was not found to affect site colonization or extinction. Mink occupancy during the initial period was negatively associated with water availability within 100 m of the survey segment. Site colonization by mink varied by month and increased with increasing developed area within 100 m of the surveyed segment, increasing channel incision, and decreasing rainfall. Probability of site extinction for mink increased as stream size and developed area within 500 m of the surveyed segment increased, and when woody vegetation was the dominant land-cover type within 1 km of the surveyed segment. The second analysis of multi-season occupancy of river otter and mink used 77 sites, 81.8% of which had ≥1 river otter detection in the study and 98.7% of which had ≥1 mink detection. Naïve occupancy differed between years but gradually increased for river otter and remained high (≥93.5%) for mink. Increasing substrate availability increased the probability of river otter detection, whereas mink detection varied by survey period. Occupancy during the initial survey period was higher in sites closer to the reintroduction points for river otter. Probability of colonization of river otter was positively associated with macroinvertebrate IBI and fish species richness, sites with high fish species richness of fish families preferred by river otter also had reduced otter extinction probability. No tested variables predicted initial occupancy for mink, but mink were more likely to colonize sites with increased fish richness and when muskrat were present during the previous period. Mink had decreased probability of extinction in sites with increasing mussel community index. My results indicate that semi-aquatic mammals in Illinois were affected by a riparian habitat, water availability, and stream community variables at both the landscape and local scale. I found high occupancy of mink, beaver, and muskrat across the entire landscape of southern Illinois, and my results suggest that the geographic range of river otter continues to expand. Relationships of occupancy of these semi-aquatic mammals to measurements of urban areas and human disturbance were not consistent across all species. Mink and river otter occupancy were both predicted by aspects of prey availability, indicating the importance of predator-prey relationships in occupancy dynamics of riparian predators. Hypotheses regarding predator pressure and changes in environmental variables were used to test the effects of river otter reintroduction on stream communities. For this objective, I used structural equation models. I compared fish and macroinvertebrate communities from before (1982-1995) and after (2005-2013) reintroduction of river otter, which occurred in 1994–1996. Fish and macroinvertebrate community data for 35 sites located throughout 6 major watersheds in southern Illinois (25,550 km2) were obtained from state agencies. Changes in stream communities were evaluated using 4 metrics (species richness, species dominance, skewness in size distribution of prey, and proportion of individuals in the size class preferred by river otter). Neither the inclusion of river otter site use nor change in stream quality, measured by change in % forest, improved models over the simple model which only included fish and macroinvertebrate communities. Overall, I found no evidence that river otter presence or change in forest cover affected stream fish and macroinvertebrate communities.
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Navarro, Cuenca Anna. "Toxicogenomic analysis of environmental impact in aquatic systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/125066.
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Field biomonitoring based on molecular biomarkers detects early warning signals of stress suffered by organisms exposed to contamination. The lower part of the Ebro River basin has a long pollution history related to the presence of a chlor-alkali plant adjacent to Flix. In addition, the Ebro River has been affected by the invasion of alien species that damage its natural ecosystem. In this thesis, Cyprinus carpio (common carp) an Dreissena polymorpha (zebra mussel) were used as a model species in laboratory and field studies intended to the development of a multimolecular biomarker approach to identify the most relevantly effects of pollutants in the field. Gene expression techniques were used to study specific physiological defensive mechanism. The application and improvement of a well-established markers in different aquatic species and following different approaches allowed to analyze modes of action and to outline effects of persistent organic and inorganic pollutants found in the field. The results showed that chronic exposure to mercury
of common carp results in increased levels of metallothionein in kidney, in scales (albeit at lower extent), but not in liver, considered as the primary detoxification organ. The measure of gene expression in scales provides the possibility of a new non-lethal method of study. Studies of toxicant effects in zebra mussel revealed that this bivalve could be used as potential sentinel specie for freshwater monitoring. Analysis of its detoxicfication mechanisms, and particularly of its ABC membrane transporters in adult and the early life stages could help understanding the survival of this species in highly contaminated areas.
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Lowcock, Diane. "The survival of Aeromonas hydrophila in aquatic systems." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385300.
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Bowles, Karl C., and n/a. "The cycling of mercury in Australasian aquatic systems." University of Canberra. School of Resource, Environmental & Heritage Sciences, 1998. http://erl.canberra.edu.au./public/adt-AUC20060609.144839.
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Methods were developed for the determination of methylmercury in natural waters and
sediments based on steam distillation and aqueous phase ethylation followed by gas chromatography-atomic fluorescence spectrometry. The methods were shown to be free
from measurable artefactual methylation of inorganic mercury and offered improved
sample throughput over existing methods. Improvements were made to existing
methods for the determination of total mercury in biota, sediments and natural waters
and dissolved mercury species in natural waters. These methods were applied to the
study of mercury cycling in two remote field sites.
The cycling of mercury species was studied in Lake Murray in Western Province,
Papua New Guinea, which has been historically noted as a region of high mercury
concentrations in fish. Concentrations of methylmercury and total mercury in the water
column were found to be variable and consistent with non-contaminated lake systems.
Concentrations of methylmercury and total mercury in the sediments were also found to
be low, except for in the south of the lake, which was influenced by an intermittent
supply of water and sediments with elevated mercury concentrations from the
Strickland River. Methylmercury concentrations in the sediments were generally higher
in the backwater areas due to littoral processes. The low concentrations of
methylmercury in the sediments and waters were inconsistent with other systems
previously studied in the northern hemisphere, showing a link between high mercury
concentrations in fish and high concentrations of methylmercury in waters or sediments.
Therefore, the biota of Lake Murray were studied in order to account for the differences
between this and other systems.
A study was conducted of the stable isotope ratios of carbon and nitrogen in biota from
Lake Murray to elucidate key food-web interactions. This study revealed that the
dominant carbon source for fish in the lake is plankton, although algae and macrophytes
may also be involved in the food-web. The methylmercury bioaccumulation factors
between trophic levels were similar to those measured in temperate systems of the
northern hemisphere. The high concentrations of methylmercury, observed in
piscivorous fish, were shown to be a consequence of the complex food-web and the
number of trophic levels in the food-chains.
The cycling of mercury species was studied in Lake Gordon and Lake Pedder in
southwest Tasmania, which has recently been identified as being in a region of high
mercury concentrations in trout and eels. The concentrations of total mercury were
found to be reasonably uniform in the waters of both lakes, spatially and temporally.
The concentrations of methylmercury in the waters were seasonally variable, and were
consistently lower in Lake Pedder than in Lake Gordon. Dilution of methylmercury
concentrations by precipitation direct to the lake surface, probably accounts for the
most of the difference in methylmercury concentrations between the lakes. Owing to
the long residence time of water in Lake Gordon, this reservoir mixes inputs of water
with varying methylmercury concentrations. Concentrations of total mercury and
methylmercury in submerged soils were low and depth profiles of mercury species in
the water column did not show evidence of a gradient of mercury concentrations due to
releases from the sediments. The concentrations of methylmercury observed in the
water column are consistent with the concentrations observed in the fish.
A budget of the mercury inputs and outputs to Lake Gordon showed that in-lake
processes and sources in the catchment areas both contributed significantly to the
concentrations of methylmercury in the lake. The methylation of mercury in Lake
Gordon appeared to mainly occur in the surface waters (< 10 m) and was not consistent
with processes leading to the methylation of mercury at the oxic/anoxic boundary
observed in seepage lakes in Wisconsin. The concentrations of total mercury and
methylmercury in bogs in the catchment areas of Lakes Gordon and Pedder, were high
and governed by the concentration of organic matter in the sediments. The processes
involved in the supply of mercury species from the Lake Gordon and Lake Pedder
catchments appear to be similar to those in drainage lakes in the temperate and boreal
regions of the northern hemisphere. The formation of the Lake Gordon and Lake
Pedder reservoirs appears to have had little impact on the mean annual concentrations
of methylmercury released to the downstream environment.
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Montemarano, Justin Joseph. "Biotic controls of decomposition dynamics in aquatic systems." Thesis, Kent State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618862.
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While environmental controllers of decomposition have been extensively studied, organic matter quality and biotic controllers of decomposition, such as detritivore preference and manipulation of detritus, are largely understudied. In the studies described in this dissertation, a range of biotic controllers of detrital dynamics in aquatic ecosystems are presented. Crayfish, as model shredders, produce a diverse pool of fine particulate organic matter (FPOM) through fragmentation of coarse particulate organic matter (CPOM) and fecal production in the laboratory. Crayfish process maple leaves at a greater rate than oak leaves, and produced a greater amount of FPOM from maple compared to oak. Crayfish-generated FPOM had lower C:N ratios and increased bacterial abundances compared to original CPOM. Further, hydropsychid caddisfly and simuliid blackfly larvae confer greater growth efficiency when reared on crayfish-generated FPOM compared to mechanically ground FPOM in the laboratory, indicating that crayfish increase bioavailability of FPOM. No differences in growth or metamorphosis of simuliid larvae were observed when larvae were lab-reared on crayfish-generated FPOM from CPOM of different tree species (i.e., sugar maple, sycamore, or white oak) or different stream conditioning times (i.e. , 30 or 150 d). This suggests that crayfish processing reduces organic matter origin effects on bioavailability. Changes in macrophyte abundance in a tropical wetland due to competition and ecosystem management can affect litter availability and litter quality. In two field-based, replacement series experiments with floating-mat macrophytes (Eichhornia crassipes and Neptunia oleracea), no interspecific competition was detected. However, E. crassipes dominated experimental enclosure biomass through attrition. Decomposition rates were faster for E. crassipes litter compared to N. oleracea litter within enclosures, but no differences in decomposition rates were detected by floating-mat species composition. Both synergistic and antagonistic diversity effects were observed on decomposition dynamics in an experiment varying litter richness from one to five species. Additionally, cattail (Typha domingensis ) eradication efforts lead to changes in the decomposition landscape within the wetland, as E. crassipes colonizes managed areas, and decomposition rates were slower for litter of T. domingensis compared to E. crassipes. The compounding effects of litter species, detritivore interactions, and anthropogenic impacts on organic matter dynamics illustrate that it is critical to consider ecosystem function in ecosystem management.
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Montemarano, Justin Joseph. "Biotic controls of decomposition dynamics in aquatic systems." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1370539247.
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Lahman, Sara Elisabeth. "The Ecotoxicological Impacts of Copper in Aquatic Systems." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1427119997.
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Koh, Wan Hon. "The interaction of cryptosporidium with aquatic biofilm systems." Thesis, Koh, Wan Hon (2013) The interaction of cryptosporidium with aquatic biofilm systems. PhD thesis, Murdoch University, 2013. https://researchrepository.murdoch.edu.au/id/eprint/20253/.
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Cryptosporidium parvum is a common, opportunistic, diarrhoeal-causing, apicomplexan pathogen in humans, of which water is an important transmission vehicle. Recently, aquatic biofilms have been recognised as environmental reservoirs for the infective stage (oocysts) of Cryptosporidium, yet their fate after being trapped within biofilms is unknown. Previous cell-associated and cell-free studies have demonstrated, controversially, that Cryptosporidium may be able to multiply extracellularly, indicating that Cryptosporidium is not an obligate intracellular microorganism, and that the environment may play an important role in shaping its life cycle. Previously published data raise the question as to whether Cryptosporidium can survive and multiply within biofilms, resulting in an increase in numbers before release into water systems, leading to possible disease outbreaks.
This study, therefore, aimed to investigate the ability of biofilms to support Cryptosporidium multiplication. This was achieved using a combination of quantitative polymerase chain reaction (qPCR), flow cytometry (immunolabeled with Cryptosporidium oocysts-specific antibody), confocal microscopy (immunolabeled with Cryptosporidium developmental stage-specific antibody) and scanning electron microscopy (SEM) techniques. To mimic a water distribution system, Pseudomonas aeruginosa biofilm flow cell systems were established and unexcysted C. parvum oocysts were constantly supplied over a 6-day period. Prior to analysis, the four analytical methods were designed and empirically optimised according to the nature of the experimental sample studied.
Quantitative PCR results showed a significant increase (P<0.001) in Cryptosporidium as the biofilm matured, with the total number of C. parvum multiplying 2-3 fold during this period. Flow cytometry analysis also revealed that the captured oocysts had undergone excystation in biofilms, confirming that the increase in Cryptosporidium number was due to Cryptosporidium multiplication. From this, various Cryptosporidium developmental stages (sporozoites, trophozoites, meronts, and merozoites) were also identified from the biofilm using confocal microscopy and SEM. A correlative study using both SEM and confocal imaging determined that the observed developmental stages were Cryptosporidium, rather than degenerate/accumulated oocysts or yeast contamination. Furthermore, SEM analysis also revealed that Cryptosporidium may form a parasitophorous vacuole independently, potentially allowing it to complete its life cycle extracellularly. In addition, certain stages of the Cryptosporidium life cycle (trophozoites, meronts, and some previously undescribed gamonts) in biofilms were identified, and shown to closely resemble stages reported in the gregarine life cycle, emphasising the possibility that Cryptosporidium has inherited the capability to multiply extracellularly from their gregarine ancestor.
In conclusion, this study has successfully shown that biofilms can support Cryptosporidium multiplication in aquatic environments and thus, also demonstrated a role for biofilms in outbreaks and spreading of this disease. The generated results are novel, offering new insights into the role of biofilms in the C. parvum life cycle, providing additional information for water authorities, aiding in the control of Cryptosporidium and biofilm-contaminated drinking water.
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Franke, Ulrich. "Applications of planar oxygen optodes in biological aquatic systems." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979703239.
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Chung, Eunhyea. "Colloidal particle-surface interactions in atmospheric and aquatic systems." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43728.
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Colloidal particles suspended in a liquid or gas phase often interact with a solid-liquid or solid-gas interface. In this study, experimental data through atomic force microscopy and neutron reflectometry and theoretical results of colloidal particle-surface interactions were obtained and compared. Atmospheric and aquatic environments were considered for the interactions of microbial colloidal particles and nano-sized silica particles with planar surfaces. Spores of Bacillus thuringiensis, members of the Bacillus cereus group, were examined as the microbial particles, simulating the pathogens Bacillus cereus and Bacillus anthracis which are potentially dangerous to human health. Model planar surfaces used in this study include gold which is an electrically conductive surface, mica which is a highly charged, nonconductive surface, and silica.
In atmospheric systems, the interaction forces were found to be strongly affected by the relative humidity, and the total adhesion force of a particle onto a surface was modeled as the addition of the capillary, van der Waals, and electrostatic forces. Each component is influenced by the properties of the particle and surface materials, including hydrophobicity and surface roughness, as well as the humidity of the surrounding atmosphere. In aquatic systems, the interaction forces are mainly affected by the solution chemistry, including pH and ionic strength. The main components of the interaction force between a microbial colloidal particle and a planar surface were found to be the van der Waals and electrostatic forces.
The results obtained in this research provide insights into the fundamental mechanisms of colloidal particle interactions with environmental surfaces in both atmospheric and aquatic systems, contributing to the understanding of the phenomena driving such interfacial processes as deposition, aggregation, and sedimentation. Thus, the results can help us describe the behavior of contaminant colloidal particles in environmental systems and subsequently devise better means for their removal from environmental surfaces.
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Tiede, Karen. "Detection and fate of engineered nanoparticles in aquatic systems." Thesis, University of York, 2008. http://etheses.whiterose.ac.uk/11072/.
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The proliferation of nanotechnology has prompted discussions over the safety of these materials to human health and the environment as their environmental fate and impact is widely unknown. This is partly due to the lack of suitable analytical techniques to detect and characterise engineered nanoparticles in the environment. This thesis aims to provide a better understanding of the environmental fate of engineered nanoparticles by developing analytical methods suitable for nanoparticle analysis in aquatic systems and employing these to laboratory-based environmental fate studies.
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McCormick, Paul V. "Patterns of microbial community development in isolated aquatic systems." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101124.
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The purpose of this research was to compare the process of microbial community development in isolated aquatic systems to the MacArthur-Wilson equilibrium theory of island biogeography and suggest alternative models for the observed patterns. Water-filled plastic containers were used as aquatic islands to investigate the colonization dynamics of protozoan, algal and microinvertebrate taxa. Polyurethane foam (PF) artificial substrates were used as sampling devices in these systems. Distance from another aquatic system was found to have a significant effect colonization in these systems. Exclusion of macroscopic organisms, however, did not strongly affect the process of microbial community development in these systems. The results of short-term (36 day) and long-term (170 day) experiments suggest that no protracted species equilibrium is achieved in these systems; an initial asymptotic increase in species richness was followed by large oscillations in the number of species. There was no correlation between rates of species colonization and the number of species present. Rates of species extinction, however, increased with increasing species number. The estimated rate of species colonization was a non-monotonic function of time, increasing during the early stages of colonization and decreasing thereafter. These results, coupled with an analysis of temporal changes in species composition suggest that microbial community development in isolated systems is a deterministic process which may be best explained by an interactive model of species succession.M.S.
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Middleton, J. "Potentially pathogenic Phytophthora isolates in irrigation systems." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354090.
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Uribe, Kaffure Ramiro. "Availability of Metal Cations in Aquatic Systems from DGT Measurements." Doctoral thesis, Universitat de Lleida, 2012. http://hdl.handle.net/10803/94522.
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Els nostres resultats indiquen que el gruix del disc de resina juga un paper fonamental en l'acumulació de metalls en sensors DGT. Per complexos parcialment làbils, la seva dissociació a l'interior del domini de resina és la principal font de metall acumulat. Aquest fenomen explica la independència del grau de labilitat amb respecte a la concentració de lligand d'un complex en DGT. Així mateix, ajuda a comprendre el reduït efecte barreja que es preveu amb els sensors DGT.Un Análisis detallado de las características dinámicas de los sensores (DGT), nos indica que la penetración de los complejos en la capa de resina aumenta dramáticamente su labilidad. Aquí, presentamos expresiones analíticas aproximadas para calcular el flujo de metal, el grado de labilidad y los perfiles de concentración en un DGT, cuando se considera que los complejos pueden penetrar en la resina. La acumulación experimental de Cd en sensores DGT en el sistema Cd-NTA, confirma los análisis teóricos.
Our analysis of the dynamic features of (DGT) devices indicates that the penetration of complexes into the resin layer dramatically increases their lability. We report approximate analytical expressions for the metal flux, the lability degree and the concentration profiles in a DGT when complexes penetration is considered. The experimental accumulation of Cd by DGT sensors in Cd-NTA systems confirmed these theoretical analyses.
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Tayab, Muhammad Rehan. "Environmental impact of heavy metal pollution in natural aquatic systems." Thesis, Brunel University, 1991. http://bura.brunel.ac.uk/handle/2438/5503.
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The distribution of heavy metals between soil and soil solutions is a key issue in evaluating the environmental impact of long term applications of heavy metals to land. Contamination of soils by heavy metals has been reported by many workers. Metal adsorption is affected by many factors, including soil pH, clay mineralogy, abundance of oxides and organic matter, soil composition and solution ionic strength. The pH is one of the many factors affecting mobility of heavy metals in soils and it is likely to be the most easily managed and the most significant. To provide the appropriate level of protection for aquatic life and other uses of the resource, it is important to be able to predict the environmental distribution of important metals on spatial and temporal scales and to do so with particular emphasis on the water column concentrations. Regulatory levels reflected in water quality criteria or standards are based on water column concentrations. Predicting water column concentrations requires a consideration of the interactions of water column contaminants with both bed sediments and suspended particulates as critical components in the assessment. The adsorption behaviour of cadmium, copper, lead and zinc onto soils is studied under the various geo-environmental conditions of pH, concentration of adsorbate and adsorbent, and solution compositions. Experiments were conducted to determine the equilibrium contact time of various adsorbates for adsorbent in different systems. Experiments were also conducted to check the efficiency of various acid-mixtures to extract heavy metal from soils into the aqueous phase. The adsorption behaviour of heavy metals onto soils was also studied from sea-water system. Soils are characterized in terms of the role of clay minerals to remove the metals from the solution phase, back-ground levels of metals, maximum adsorption capacity to adsorb various heavy metals from different adsorption systems, and type of surface sites present. The experimental data of metal adsorption is described by Langmuir adsorption model. The adsorption data are also expressed in terms of surface loading, surface acidity, adsorption density, and affinity of soils for heavy metals in different adsorption systems. Ecological implications of changes in physical and chemical conditions in aquatic systems on heavy metals uptake by soils are also discussed. This research covers the following areas: the environmental impact of heavy metal discharge into the aquatic systems, the study of the mobility patterns of different heavy metals as function of geo-environmental conditions, and determination of the pathways and the ultimate fate of heavy metals in the environment.
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North, Jessica C., and n/a. "Stable isotope tracers of landfill leachate impacts on aquatic systems." University of Otago. Department of Chemistry, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070504.144317.
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The present study aimed to determine whether stable isotope techniques can be universally applied to detect landfill leachate contamination in aquatic systems. Results of analysis of ��C in dissolved inorganic carbon ([delta]��C-DIC), deuterium and �⁸O in water ([delta]D-H₂O and [delta]�⁸O-H₂O), and �⁵N of dissolved inorganic nitrogen components ([delta]�⁵N-NH₄⁺ and [delta]�⁵N-NO₃⁻) were presented for leachate, surface, and ground water samples collected from seven landfills located throughout New Zealand between 2003 and 2006. The unique conditions within a landfill lead to measurable fractionations in the isotopic ratios of the products of degradation. Results of isotope and ancillary parameter analyses enabled the discernment of different types of leachate, resulting from different microbial processes within the landfill environment. The isotopic characterisation of leachate enabled improved interpretation of geochemical data from potentially impacted surface and ground waters, and provides useful insight to landfill development for landfill operators. A general isotopic fingerprint delineated by [delta]��C-DIC and [delta]D-H₂O values showed leachate to be isotopically distinct from uncontaminated surface and ground water for samples analysed in the present study. However, not all water samples identified as leachate-impacted via site-specific assessments exhibited isotopic values that overlapped with the general leachate fingerprint. This highlights the need to investigate each site individually, within the context of a possibly global leachate isotope signature. Site-specific investigations revealed the effectiveness of applying [delta]�⁸O-H₂O and [delta]�⁵N-NH₄⁺ or [delta]�⁵N-NO₃⁻, in addition to [delta]��C-DIC and [delta]D-H₂O analyses, to the detection of leachate impact on aquatic systems. Furthermore, ancillary parameters such as alkalinity and ammonium concentration enabled the construction of simple isotope mixing models for an estimate of the quantity of leachate contribution. Results of isotopic investigations of stream biota suggested potential for the development of bio-indicators to monitor leachate influence on aquatic ecosystems in landfill-associated streams. The present study demonstrated the probative power of stable isotope techniques applied to investigations of leachate impact on landfill-associated aquatic systems.
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Gimpel, Jenny. "Trace metal speciation and bioavailability in aquatic and soil systems." Thesis, Lancaster University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414956.
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Aldrich, Annette Patrizia. "The redox speciation and biogeochemistry of iron in aquatic systems." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367287.
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Pickard, Amy Elizabeth. "Assessing the photoreactivity of peatland derived carbon in aquatic systems." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28774.
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Northern peatlands are a globally important soil carbon (C) store, and aquatic systems draining peatland catchments receive a high loading of dissolved and particulate forms of C from the surrounding terrestrial environment. Once incorporated into the aquatic environment, internal processes occur to modify the C pool. Of these, photo-processing preferentially targets terrestrially derived C and therefore might have a significant effect on the C budget of peatland draining aquatic systems. The overarching aim of this study was to investigate photochemical processing of C in Scottish peatland draining aquatic systems in order to determine the importance of this pathway in aquatic biogeochemical cycles. For initial laboratory experiments, water samples from a peatland headwater stream (Auchencorth Moss, SE Scotland) were collected. Laboratory based irradiation experiments were conducted at a range of temperatures, and different filtration treatments, including unfiltered samples, were employed to understand the fraction of C most susceptible to photo-processing. UV irradiation and temperature had a significant effect on DOC and gas headspace concentrations, with Q10 values of ~1.42 and ~1.65 derived for CO2 and CO photoproduction in unfiltered samples, respectively. However, filtration treatment did not induce significant changes in gaseous C production between light and dark samples, indicating that the experimental conditions favoured breakdown of DOC rather than POC to CO2 and CO. In all light treatments a small but significant increase in CH4 concentration was detected. These data were compared to results from experiments conducted in ambient light and temperature conditions. DOC normalised CO2 photoproduction was an order of magnitude lower than in laboratory conditions, although relative abundances of C species within overall budgets were similar and these experiments demonstrated that ambient exposure is sufficient to generate photo-processing of aquatic peatland C. Overall these data show that peatland C, particularly the < 0.2 μm fraction, is highly photoreactive and that this process is temperature sensitive. Further laboratory irradiation experiments were conducted on filtered water samples collected over a 13-month period from two contrasting aquatic systems. The first was the headwater stream draining Auchencorth Moss peatland with high DOC concentrations. The second was a low DOC reservoir (Loch Katrine, C Scotland) situated in a catchment with a high percentage peat cover. Samples were collected monthly from May 2014 to May 2015 and from the stream system during two rainfall events. Significant variation was seen in the photochemical reactivity of DOC between the two systems, with total irradiation induced change typically two orders of magnitude greater and DOC normalised CO2 production a factor of two higher in the headwater stream samples. This is attributed to longer water residence times in the reservoir rendering a higher proportion of the DOC recalcitrant to photo-processing. Overall the magnitude of photo-induced C losses was significantly positively correlated with DOC concentration in the headwater stream, which varied seasonally with highest concentrations detected in late autumn and winter. Rainfall events were identified as important in replenishing the stream system with photoreactive material, with lignin phenol data indicating mobilisation of fresh DOC from woody vegetation in the upper catchment during a winter rainfall event. Whilst these data clearly demonstrate that peatland catchments generate significant volumes of photoreactive DOC, the degree to which it is processed in the aquatic environment is unclear. Field investigations were undertaken to address this uncertainty. In-situ experiments with unfiltered water samples in light and dark conditions were conducted in two contrasting open water peatland pool systems. At the high DOC site (Red Moss of Balerno, SE Scotland), DOC concentrations in surface light exposed samples decreased by 18% compared to dark controls over 9 days and light treatments were enriched in CO2 and CH4. Photochemical processing was evident in δ13C-DOC and δ13C-DIC signatures of light exposed samples, which were enriched and depleted, respectively, relative to dark controls (+0.23 ‰ and -0.38 ‰) after 9 days of surface exposure. At the low DOC site (Cross Lochs, Forsinard, N Scotland) net production of DOC occurred in both light and dark samples over the experiment duration, in part due to POC breakdown. δ13C-DIC signatures indicated photolysis had occurred in light exposed samples (-1.98 ‰), whilst δ13C-DOC data suggest an absence of photo-processing, as the signatures in both treatments were similar. Accounting for light attenuation through the water column, 46 ± 4.9 and 8.7 ± 0.5 g C-CO2 eq m−2 yr−1 was processed by photochemical and microbial activity in peatland pools within the catchments at the high and low DOC sites, respectively. At both sites, light driven processing was responsible for a considerable percentage (34 and 51%) of gaseous C production when compared to equivalent estimates of microbial C processing and thus should be considered a key driver of peatland pool biogeochemical cycles. It is clear from this study that temperature, seasonal cycles, rainfall events and water residence time provide strong controls on the photoreactivity of aquatic C in Scottish peatland systems. The photo-processing pathway has the potential to alter the C balance of peatland catchments with a high percentage coverage of aquatic systems. Under climate change scenarios where light, temperature and rainfall conditions are expected to change, this process may become increasingly important in aquatic C cycling, particularly if the upward trend in DOC concentrations in northern aquatic systems continues.
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Thrush, Mariah A. "Analyzing Algal Diversity in Aquatic Systems Using Next Generation Sequencing." Ohio University Honors Tutorial College / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1366807717.
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Pletcher, Leeanna. "The Ecology of Fear: Oviposition and Colonization in Aquatic Systems." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1587.
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Amphibians and aquatic invertebrates have complex life histories that link aquatic and terrestrial food webs. It has been suggested that amphibian reproduction is an important source of carbon to some aquatic systems. This process of energy flow may be shaped by shifts in habitat selection in response to predators. We hypothesized that predators decrease colonization and oviposition of prey, reducing active inputs. Thus predation risk is expected to shift the relative amounts of active and passive subsidies. We manipulated the presence of fish predators in aquatic mesocosms. Results suggest hylid treefrog eggs and hydrophilid beetles were less abundant in predator treatments. This difference in oviposition and colonization translated into small reductions in calories and ash free dry mass of active inputs. However, passive allochthonous inputs were more than double active amounts and variable, therefore relative amounts of active and passive inputs did not differ across the levels of predation risk.
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Regmi, Bijay. "Database Design and Optimization for Telemetric Aquatic Species-Tracking Systems." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/honors_theses/118.
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Tracking an individual species has always been a challenge for scientists, especially when one has to make sure to not change its natural movement pattern. When the number of individuals being tracked is increased and water is added to the equation, the task becomes next to impossible. But thanks to technologies and tracking methods like telemetry, the task of tracking any species without affecting the natural movement pattern has not only become a reality but easily accessible to scientists. Underwater acoustic telemetry has become a standard tool for fisheries biologist to study the movement pattern of the fish (Heupel). This project develops a minimalistic database designed to meet the needs of the telemetry systems. The database is optimized for storing a large number of datasets generated by the telemetry system and also for the most common queries run against the system.
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Cen, Lejun. "Fish-like locomotion using flexible piezoelectric composites for untethered aquatic robotics." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45864.
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The capacity of humankind to mimic fish-like locomotion for engineering applications depends mainly on the availability of suitable actuators. Researchers have recently focused on developing robotic fish using smart materials, particularly Ionic Polymer-Metal Composites (IPMCs), as a compliant, noise-free, and scalable alternative to conventional motor-based propulsion systems. In this thesis, we investigate fish-like self propulsion using flexible bimorphs made of Macro-Fiber Composite (MFC) piezoelectric laminates. Similar to IPMCs, MFCs also exhibit high efficiency in size, energy consumption, and noise reduction. In addition, MFCs offer large dynamic forces in bending actuation, strong electromechanical coupling as well as both low-frequency and high-frequency performance capabilities. The experimental component of the presented work focuses on the characterization of an MFC bimorph propulsor for thrust generation in a quiescent fluid as well as the development of a preliminary robotic fish prototype incorporating a microcontroller and a printed-circuit-board (PCB) amplifier to generate high actuation voltage for battery-powered free locomotion. From the theoretical standpoint, a reliable modeling framework that couples the actuator dynamics, hydroelasticity, and fish locomotion theory is essential to both design and control of robotic fish. Therefore, a distributed-parameter electroelastic model with fluid effects and actuator dynamics is coupled with the elongated body theory. Both in-air and underwater experiments are performed to verify the incorporation of hydrodynamic effects in the linear actuation regime. For electroelastically nonlinear actuation levels, experimentally obtained underwater vibration response is coupled with the elongated body theory to predict the thrust output. Experiments are conducted to validate the electrohydroelastic modeling approach employed in this work and to characterize the performance of an MFC bimorph propulsor. Finally, a wireless battery-powered preliminary robotic fish prototype is developed and tested in free locomotion at different frequency and voltage levels.
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Dieter, Daniela [Verfasser]. "Phosphorus and leaf litter turnover in temporary aquatic systems / Daniela Dieter." Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1036130185/34.
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Pestana, Carlos Joao. "Monitoring and regulating cyanobacterial metabolites (microcystins and geosmin) in aquatic systems." Thesis, Robert Gordon University, 2012. http://hdl.handle.net/10059/729.
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Cyanobacterial secondary metabolites can cause serious harm to animals and humans (cyanotoxins) and can have a major financial impact on the potable water and aquaculture industries (taste and odour compounds). Understanding the factors that affect cyanotoxin production can help in exploring means for the control of these secondary metabolites. One of the most prominent cyanotoxins are microcystins and their sister compound nodularin. The biological role of microcystins is poorly understood. A pheromonal effect was observed applying a novel stable isotope labelling (15N) method. Microcystin- LR has been shown to stimulate culture growth, limit microcystin synthesis, and affect the distribution of microcystin-LR between the intra- and extracellular matrices. Furthermore the control of microcystins in potable water has been explored applying photocatalysis over titanium dioxide. A novel product called Photospheres™ was assessed in its photocatalytic efficiency in the destruction of 12 microcystin analogues and nodularin. The photocatalytic efficiency of the Photospheres™ was further explored in the degradation of four common waste water pollutants (2-chlorophenol, p-cresol, Acid Orange 74, and trichloroethylene) and in a custom built reactor using light emitting diodes as source of irradiation. The monitoring and regulation of cyanobacterial taste and odour compounds, especially geosmin and 2- methylisoborneol is important in the potable water and aquaculture industries. A rapid, robust, sensitive, and cost-effective analysis method using SPE-GCMS has been developed and is capable of detecting both compounds to sub nano gram levels. The method was successfully applied on spiked laboratory and environmental samples (loch and fishfarm waters). The photocatalytic destruction of both 2-methylisoborneol and geosmin was explored with a custom built flow reactor that was able to degrade > 95 % of both compounds in spiked and environmental samples. Furthermore the application of silicone rubber membranes as passive samplers was explored in spiked and environmental samples, demonstrating that silicone rubber membranes can successfully be used in environmental applications to deliver rapid and accurate determinations of both 2-methylisoborneol and geosmin.
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Dimberg, Peter H. "Predictions Within and Across Aquatic Systems using Statistical Methods and Models." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263283.
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Aquatic ecosystems are an essential source for life and, in many regions, are exploited to a degree which deteriorates their ecological status. Today, more than 50 % of the European lakes suffer from an ecological status which is unsatisfactory. Many of these lakes require abatement actions to improve their status, and mathematical models have a great potential to predict and evaluate different abatement actions and their outcome. Several statistical methods and models exist which can be used for these purposes; however, many of the models are not constructed using a sufficient amount or quality of data, are too complex to be used by most managers, or are too site specific. Therefore, the main aim of this thesis was to present different statistical methods and models which are easy to use by managers, are general, and provide insights for the development of similar methods and models. To reach the main aim of the thesis several different statistical and modelling procedures were investigated and applied, such as genetic programming (GP), multiple regression, Markov Chains, and finally, well-used criteria for the r2 and p-value for the development of a method to determine temporal-trends. The statistical methods and models were mainly based on the variables chlorophyll-a (chl-a) and total phosphorus (TP) concentrations, but some methods and models can be directly transferred to other variables. The main findings in this thesis were that multiple regressions overcome the performance of GP to predict summer chl-a concentrations and that multiple regressions can be used to generally describe the chl-a seasonality with TP summer concentrations and the latitude as independent variables. Also, it is possible to calculate probabilities, using Markov Chains, of exceeding certain chl-a concentrations in future months. Results showed that deep water concentrations were in general closely related to the surface water concentrations along with morphometric parameters; these independent variables can therefore be used in mass-balance models to estimate the mass in deep waters. A new statistical method was derived and applied to confirm whether variables have changed over time or not for cases where other traditional methods have failed. Finally, it is concluded that the statistical methods and models developed in this thesis will increase the understanding for predictions within and across aquatic systems.
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Law, Alan. "Evaluation of the ecological impacts of beaver reintroduction on aquatic systems." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/20767.
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The extent and quality of freshwater systems is declining globally. Combined with past drainage, straightening and flow regulation, current systems are often functional but not pristine. Conservation, creation and restoration of freshwater systems is common but requires significant planning, resources and active monitoring and may only be a short-term solution to the long-term problem of destruction and loss of riparian zones. Beavers (Castor spp.) have the ability to create physical and biological habitat heterogeneity through the construction of woody debris dams, thereby restoring lost natural discontinuities in freshwater systems. Beavers may thus offer a natural, more passive solution to the need for wetland restoration or creation and the problem of homogenisation of watercourses. As such, numerous beaver reintroductions and introductions have been undertaken based in part on restoring this lost natural heritage. However, it is crucial to be able to predict the potential effects on existing biota of physical modifications by beavers to ecosystems, especially in the light of further population expansion, whilst also disentangling these effects from other influences, namely herbivory. The impact of beavers on aquatic systems was studied using a combination of field-based surveys and experiments, using aquatic plants and macro-invertebrates as indicators of hydromorphological changes and to quantify the effects of direct foraging. The research presented in this thesis demonstrates beaver adaptive foraging behaviours between terrestrial and aquatic habitats, whilst feeding highly selectively, optimally and opportunistically, using the white water lily (Nymphaea alba) as a model species. The effects of beaver foraging on the aquatic plant resource and diversity was low over short time spans (e.g. 1 year), but when selective foraging was assessed over greater time scales (e.g. 10 years) the effects of foraging were distinct. Significant changes in aquatic plant height, biomass, richness, diversity and composition were observed over this time period due to selective grazing on large rhizomatous species (e.g. Menyanthes trifoliata). These direct effects occurred even though changes in water levels, which are commonly believed to be the main driver of beaver influence on aquatic vegetation, were negligible. In a separate study in Sweden where beavers commonly constructed dams, with ponds then forming upstream, the aquatic plant and coleoptera species richness and composition differed in comparison to adjacent non-beaver created wetlands. Therefore, having a range of wetland types in the environment increases physical and biological heterogeneity creating unique niches that are exploited by disparate taxa. The construction of a series of dams within a single reach of stream flowing through a Scottish agricultural landscape also increased physical habitat diversity. Distinctive macroinvertebrate assemblages and modified functional diversity were associated with each dominant habitat type in the stream, resulting in increased landscape scale richness. The findings of this thesis confirm that beaver engineering and foraging has the potential to create unique and highly heterogeneous wetland and stream habitats within landscapes that enhances richness and diversity for multiple species groups. This thesis also supports part of the rationale for the trial reintroduction of beaver to Scotland that beavers can restore degraded habitats.
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Milwain, Garry K. "Relationships of pesticides, agri-aquatic systems and livelihoods : insights from Asia." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/21821.
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In Asia, the recent rapid growth in production of higher value, more pesticide intensive, horticultural crops and inland aquatic foods in linked agri-aquatic systems poses numerous environmental, health and wider livelihood threats in these often multi-use aquatic systems. ‘Green Revolution’ technologies have enhanced food security and pesticides have been promoted, however, the sustainability of prolonged pesticide use from a functional, environmental and socio-economic perspective is increasingly questionable. Further, despite international pesticide trade agreements and country-specific legislation, illegal practices still prevail. In Thailand and Sri Lanka the influence of pesticide marketing and regulation on pesticide use and hazards was investigated. Community livelihood relationships with three very different agri-aquatic systems (in Central and Northeast Thailand and Northwest Sri Lanka), pesticide use and associated aquatic and health hazards were explored with respect to surface water use and well-being status. Quantitative and qualitative data collection methods utilised participatory community appraisals, household surveys, pesticide fate in surface waters and dietary risk assessment and modelling, key informant semi-structured interviews and stakeholder workshops, to assess these relationships. Enhanced environmental and human pesticide hazards were contributed by pesticide sales incentives and weak regulation allowing illegal practices to prevail. Preliminary risk assessments found greater aquatic and human dietary pesticide hazards within communities, with the poorest at greatest vulnerability from applying pesticide and higher dependency on threatened natural aquatic food resources. The poorest in communities were most likely to overuse pesticide in Sri Lanka and were most vulnerable to illegal practices in the pesticide industry that are often linked with unauthorised traders and credit arrangements. Most horticultural production is for fresh wholesale markets with no food safety controls, and despite growing demand for safer horticultural produce, most farmers perceive pesticides as necessary, the associated hazards low and have little knowledge of safe food production and markets. These circumstances help sustain pesticide use. Some unofficial certification and misleading labelling in the ‘safe’ fruit and vegetable sector in Thailand potentially misinforms consumers and undermines trust that may threaten pesticide reduction efforts. Good Agricultural Practice (GAP) and vegetable Integrated Pest Management (IPM) are evolving practices and techniques of producing horticultural crops with less or no pesticide, the latter sometimes through Farmer Field Schools (FFS), however, evidence of success varies. Teaching through lectures and more lengthy and costly participatory methods is evident, with the former more successful on GAP and higher educated farmers and the latter with IPM and worse-off farmers, particularly when addressed within livelihood issues as a whole. However, production scale, farmer enthusiasm, produce marketing and facilitator expertise all influence outcomes, particularly with IPM, whilst proper evaluation could improve progress. Growing rural consumer interest in organic produce offers further incentives for small to medium scale farmers to implement IPM and reduce pesticide use and hazards. As value of aquatic resources was an incentive to reducing pesticide use, particularly the most dangerous products, exploration of this component of agri-aquatic systems is another exciting prospect for empowering farming community livelihoods over established and failing fear based chemical practices. Such new practices may lead the way towards affordable and trustworthy agri-aquatic systems produce with ethical certification. Greater pesticide use savings on a wider scale come from use of efficient flat fan spray nozzles compared with conventional pesticide spray nozzles. Complementary policies and stakeholder co-operation could aid pesticide use and hazard reduction efforts. A number of recommendations arose from the research.
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Henkanaththegedara, Sujan Maduranga. "Ecological Complexity of Non-Native Species Impacts in Desert Aquatic Systems." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26697.
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Without an adequate understanding of complex interactions between native and non-native species, management of invasive species can result in unforeseen detrimental impacts. I used both field and laboratory experiments to study reciprocal species interactions between the endangered Mohave tui chub (Siphateles bicolor mohavensis) and invasive western mosquitofish (Gambusia affinis). I also examined the impacts of both fish species on the aquatic invertebrate communities in desert springs. I demonstrate a case of intraguild predation (IGP) as a mechanism facilitating co-persistence of the endangered Mohave tui chub with invasive mosquitofish using field mesocosm experiments. In this case of IGP, adult tui chub prey on adult and juvenile mosquitofish, while adult mosquitofish prey on tui chub eggs and/or larvae. I conducted laboratory predation trials to assess if IGP was size-structured due to predator gape-limitation. I explored sex specific differences in gape-size limitation in mosquitofish, because mosquitofish are sexually dimorphic. Larval tui chubs had lower survival in the presence of female mosquitofish than in the presence of males. Reciprocally, male mosquitofish had lower survival than the females in the presence of Mohave tui chub. These results combined with vulnerability modeling supported that IGP in this system is size structured based on gape-size limitation. These results collectively suggest size-structured IGP may facilitate the co-persistence of these two fish species. My findings also suggest that mosquitofish may not be a limiting factor for the persistence of the endangered Mohave tui chub. Further, habitats currently harboring mosquitofish were considered as future refuge habitats for Mohave tui chub, a management option previously un-available. In addition to such reciprocal interactions between fish species, recently established fish populations may impact unique invertebrate communities. Mesocosm experiments with sympatric and allopatric populations of tui chub and mosquitofish showed negative impacts of both fish species on changes of invertebrate community structure. Specifically, fish caused population declines and, in some cases, extirpations of various invertebrate taxa. These results suggest important conservation implications of invasive fish as well as protected fish transplants into fishless desert springs. Overall my research emphasizes the complexity of ecological interactions between native and non-native fish species in desert aquatic systems.
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Park, Sujung. "Behaviour and uptake of engineered gold nano particles in aquatic systems." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/7935/.
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Nanotechnology is a rapidly growing industry of global economic importance. However, there is concern that the unique properties of engineered nanoparticles (ENPs) which can make them useful to society could mean that they pose a risk to the natural environment. There are still many uncertainties around the behaviour of ENPs in aquatic systems, their capacity to be taken up by aquatic organisms, and their potential toxic effects. This study therefore used four different surface functionalised gold (Au) nanoparticles as exemplars and explored their behaviour in various aquatic systems and their uptake into aquatic organisms. Studies into the behaviour of the study ENPs in standardized ecotoxicity test media showed that the particles exhibit very different aggregation behaviour depending on the test media type, the chemical composition of the test media and surface capping of the nanoparticles. Based on the results of the aggregation studies in a range of natural waters, a series of methods to predict size of Au particles in different water chemistries were developed. Results showed that there would likely be big differences in the aggregation of the different Au nanoparticle types in UK water types which implies that aggregation of ENPs will vary widely across surface waters. The uptake of the four Au nanoparticles into the aquatic invertebrate, Gammarous pulex, did not show obvious relationship between the aggregation state in a treatment and uptake suggesting that the widely accepted assumption that ENP uptake is related to particle size does not hold for the range of aggregation states studied. The results of this thesis showed that the degree of aggregation of ENPs and uptake into aquatic organisms would vary depending on the surface functionalisation of the ENPs and water chemistry. The results imply that aggregation of ENPs will vary widely across surface waters which make assessment of risks a challenge. Additionally, the uptake data indicate that factors other than particle size determine uptake of ENPs into organisms. Therefore, it may be necessary to develop new paradigms and models for risk assessment of ENPs.
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Reinhold, Dawn Marie. "Fate of fluorinated organic pollutants in aquatic plant systems studies with lemnaceae and lemnaceae tissue cultures /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26506.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Saunders, F. Michael; Committee Member: Huang, Ching-Hua; Committee Member: Hughes, Joseph; Committee Member: Loeffler, Frank; Committee Member: Pullman, Gerald; Committee Member: Spain, Jim. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Samland, Marc C. (Marc Christopher). "An assessment of reverse electrodialysis for application to small-scale aquatic systems." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118673.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 84-88).
Reverse electrodialysis (RED) is a means by which to produce electrical power through the flow of Na+ and Cl- ions from seawater to fresh water across ion selective membranes. While current research has largely focused on utilizing RED for large-scale commercial power, this thesis explores the feasibility of using RED as a power source for remote sensing devices and unmanned underwater vehicles, with a specific focus on the Arctic Ocean. A parameter sweep is developed using MATLAB in order to estimate the ideal dimensions and flow rates for an RED stack with respect to its volumetric power density. Unlike previous models, this model accounts for considerations unique to RED's application to unmanned underwater vehicles and remote sensing devices in variable environmental conditions. The model maintains broad generality for use with a variety of RED design configurations, while also demonstrating agreement with empirical data collected from specific experimental tests. The computational model is validated by empirical data from three previous studies and used to find a specific and volumetric power density for RED of 2.35 W/kg and 206 �10⁻³ W/cm³ at 298K with salt concentrations of 0.7 and 35 g NaCl/ kg H₂O. This thesis then compares RED to other environmental energy harvesting systems and determines RED to be a competitive power source within the environmental constraints of the Artic. Regarding the use of RED as a secondary power source to charge lithium ion batteries, it is found that it would require an RED stack over four days to recharge a lithium ion battery of equal mass and over thirteen days for a battery of equal volume. For use with low power systems requiring constant power, an RED stack could supply more power than a lithium ion battery of equivalent mass for durations longer than three days and ten days for one of equivalent volume.
by Marc C. Samland.
S.M.
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Motitsoe, Samuel Nkopane. "Mapping Nitrogen Loading in Freshwater Systems: Using Aquatic Biota to Trace Nutrients." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020819.
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The majority of river systems in developing countries like South Africa, are found in catchments areas that are densely human populated, therefore are subjected to intense land-use and developmental pressures. Anthropogenic nutrient pollution or the excessive addition of nutrients is one important type of stressors that river systems often experience through intense land-use, which includes poor waste management and agricultural practices. Such events are referred to as the “urban syndrome”, were human populations and developmental demands outpace ecosystem services. Traditional measurements of water quality (e.g. physicochemical and micro-nutrient assessments) and biological monitoring (e.g. South African Scoring System 5, SASS5) techniques for assessing ecosystem health have being widely used to reflect the ecological health and status of river systems. However these techniques have a number of challenges associated with their application. SASS5 which is used most prevalently in southern Africa for example, can only be applied in lotic systems, it is habitat dependent and finally (but arguably most importantly) it cannot identify the source of pollution inputs. Recent laboratory studies using stable isotopic ratios (δ15N and δ13C) of aquatic macrophytes (duckweed: Spirodela sp.) have shown successful differentiation between different N-sources and the mapping of temporal and spatial nitrogen dynamics in freshwater systems. Furthermore δ15N isotopic values of Spirodela sp. showed the capability to act as an early warning indicator of eutrophication, before the onset of aquatic ecosystem degradation. Therefore, this study aimed to field test the potential of sewage plume mapping using the stable isotopic values of Spirodela sp. and aquatic macroinvertebrates at nine study sites on the Bloukrans-Kowie River and ten study sites on the Bushman-New Year’s River systems in the Eastern Cape, South Africa. And more...
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yuan, chenyi. "The Photofate of Pesticides and Dissolved Organic Matter in Diverse Aquatic Systems." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu148710499961032.
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O'Reilly, Kirk Thomas. "The role of copper in the apparent aluminum toxicity of aquatic systems." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3522.
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The effect of variations in aluminum and copper concentrations on the growth rate and enzyme activity of the green alga Scenedesmus quadricauda was investigated. The goal was to determine which chemical species control the biological parameters. The computer program MINEQL (Westal et al 1976) was used to estimate chemical speciation. In the prevalence of both metals, algal growth rate and alkaline phosphatase activity could be correlated to cupric ion activity. The activity of isolated bacterial alkaline phosphatase was found to be a function of both total copper concentration and cupric ion activity. A model was developed to predicted the effects on alkaline phosphatase of perturbation in aquatic chemistry.
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Jones, Susan Elizabeth. "Extracellular enzyme activity in aquatic systems with particular emphasis on attached freshwater microbial communities." Thesis, Bangor University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278143.
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Wangpen, Prayadt. "The role of shelter in cherax abidus and bidyanus bidyanus polyculture systems." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/2312.
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Research into the polyculture of finfish and crayfish has been conducted in Western Australia for over a decade now. This research was instigated out of a need to increase revenues from freshwater crayfish farmers wishing to diversify their income base with a view to increasing profitability and reducing risk. It has become clear that several key variables dictate how the polyculture system (i.e. polysystem) will perform. These include biological factors like: size of participating species, relative densities, gender, planktonic turbidity, natural feeds; and abiotic factors like: light intensity, clay turbidity, floating cages for segregation, water quality, and habitat/shelter complexity. Many of these factors can be controlled / adjusted by the manager of the polysystem to maximise performance, production and profitability.While much of the research to date has focussed on the marron (Cherax tenuimanus) industry, it is also important to realise that an understanding of these factors can also assist other crayfish polysystems, like integrated agri-aquaculture systems containing yabbies (Cherax albidus). Some of the factors that influence how the system will perform may become more prevalent, like suspended clay turbidity and the associated role of light intensity in species interactions, or shelter complexity and the resulting choice of shelter material. But overall, they are the same basic variables and we must understand how they affect the particular multi-species system that we are dealing with. There is a lot to be learned from the literature on how these variables affect multi-species aquatic environments in the wild. Perhaps aquaculturists have not considered this enough in the past. Some farmers seem to believe that these variables are different JUST because it is a culture system. This is not true.The variables will take on different levels in a culture system (i.e. a manager will stimulate turbidity, provide artificial feeds, stock different sizes, and supply particular types of shelter) BUT the actual variables themselves (e.g. food, density, light, shelter) are basic to ALL aquatic ecosystems. Other researchers have looked at important factors like density, gender, and light intensity / turbidity in crayfish polysystems - but the issue of habitat complexity and the role of shelter has not been adequately addressed. This thesis will investigate some basic questions about shelter and endeavour to apply them to crayfish polysystems, with the emphasis on marron (C. tenuimanus) and yabbies (C. albidus) because these are the two most commercially important species of crayfish in Western Australia. Importantly, it should be noted that due to the invasive nature of yabbies, and their apparent ability to displace native marron in the wild, findings will be related to yabby-marron competition / displacement where relevant. We need to know many things about shelter: what type is best in a multi-species system? Should the shelter size match the crayfish size? Do marron have different requirements for shelter than yabbies? Does it matter who gets first use of a shelter (i.e. prior residence effect)? Can we learn about crayfish shelter requirements by examining the behaviour / plasticity of crayfish species? If crayfish are stocked with finfish and they retreat into shelter as a predator-avoidance measure, is the complexity important given that their densities will be higher? If densities of crayfish inside shelters are higher in polysystems, will cannibalism be a concern, particularly when conditions are right for moulting? Does visual recognition and / or chemo-detection of a predator affect the shelter usage by marron or yabbies?Does temperature affect shelter usage behaviour for a burrowing species like yabbies? Shelter is an important factor in the life history of a freshwater crayfish and an understanding of its influence on different species is important for maximising system performance. Crayfish are categorised depending on their ability to construct shelters (i.e. burrows). Yabbies have evolved in systems with fluctuating water quality and many predators and, as such, have learned to burrow (to escape drought and also to escape predators). Marron, on the other hand, are a non-burrowing native crayfish species that have existed with relatively few predators in the South-West. As a result, marron are less capable of modifying their behaviour when confronted with a predator (i.e. low behavioural plasticity). Species with high plasticity, like yabbies, are more capable of adapting to new environments, because they can change their behaviour to increase their chance of survival. Therefore we can expect yabbies and marron to utilize habitats differently and we should compare these behaviours as a basis to developing management strategies. This type of knowledge may also assist with managing the translocation and spread of yabbies in the wild and their displacement of native marron.Within multi-species systems, the physical structure of shelter plays an important role inprotecting crayfish and the perfect shelter would not only provide safety from co-stocked finfish, but also from conspecific cannibalism. Given the different life histories and behaviours, it is probable that both species of crayfish will have different refuge requirements.Over the course of this four-year investigation, trials were conducted in four culture systems (72L aquariums, 300L circular tanks, 80t mesocosm tank, and 720m2 earthen ponds) using marron and yabbies as the species of interest.Silver perch and Murray cod were chosen as the finfish species of interest as they appear to have the highest aquaculture potential for native freshwater finfish in Australia at the present time. Further, both of these fish have been documented as potential predators of crayfish, resulting in a challenge to understand the role of shelter in minimising the negative effects of fish-crayfish interactions within a polysystem. This study has confirmed that shelter plays a critical role in multi-species system dynamics. In the case of polysystems, it will affect both interspecific and intra-specific interactions, ultimately governing production and profitability, along with the other, previously defined factors. This means that the manager of a polysystem can influenceproductivity by understanding: a) the behavioural characteristics and biology of the crayfish; b) the feeding biology of the finfish; and c) the system variables (both biotic and abiotic) that will affect the overall well being of the fish and crayfish. In the case ofshelter, the manager should understand the available shelter types, the appropriatedensities, the importance of matching complexity to the crayfish size, and the prior residence effect when choosing a timing strategy for stocking and harvesting. Prior residence increased resource holding potential for both marron and yabbies in the short term. In fact, prior residence was a stronger determinant of successful sheltering than crayfish gender or species. However, in longer-term trials the physical size of the crayfish (larger animals evicted smaller animals) and reproductive status (berried females were successful at evicting all other crayfish) were more important factors in determining successful shelter acquisition, although the temporal variations (i.e. growth and release of young) complicate the issue.When stocking crayfish of different sizes, and in polysystems, the correct size of shelter becomes critical, as smaller individuals will be forced to leave over-sized shelter and locate a shelter commensurate with their own body size to avoid predators. This is relevant to crayfish nurseries where complex habitat is paramount for juvenile cohorts that display variation in sizes and gender. The expansion of crayfish polyculture holds considerable promise; however, furtherinvestigations are required into shelter complexity within floating fish cages, shelter types and arrangement of shelters within ponds (for increased production and ease-of-harvesting), potential of yabbies in polyculture (comparison of monosex and hybrid strains), and the impact of shelter on escape behaviour of marron in a polysystem.
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Dimberg, Peter. "Determining Chlorophyll-a Concentrations in Aquatic Systems with New Statistical Methods and Models." Licentiate thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160303.
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Chlorophyll-a (chl-a) concentration is an indicator of the trophic status and is extensively used as a measurement of the algal biomass which affects the level of eutrophication in aquatic systems. High concentration of chl-a may indicate high biomass of phytoplankton which can decrease the quality of water or eliminate important functional groups in the ecosystem. Predicting chl-a concentrations is desirable to understand how great impact chl-a may have in aquatic systems for different scenarios during long-time periods and seasonal variation. Several models of predicting annual or summer chl-a concentration have been designed using total phosphorus, total nitrogen or both in combination as in-parameters. These models have high predictive power but are not constructed for evaluating the long-term change or predicting the seasonal variation in a system since the input parameters often are annual values or values from other specific periods. The models are in other words limited to the range where they were constructed. The aim with this thesis was to complement these models with other methods and models which gives a more appropriate image of how the chl-a concentration in an aquatic system acts, both in a short as well as a long-time perspective. The results showed that with a new method called Statistically meaningful trend the Baltic Proper have not had any change in chl-a concentrations for the period 1975 to 2007 which contradicts the old result observing the p-value from the trend line of the raw data. It is possible to predict seasonal variation of median chl-a concentration in lakes from a wide geographically range using summer total phosphorus and latitude as an in-parameter. It is also possible to predict the probability of reaching different monthly median chl-a concentrations using Markov chains or a direct relationship between two months. These results give a proper image of how the chl-a concentration in aquatic systems vary and can be used to validate how different actions may or may not reduce the problem of potentially harmful algal blooms.Koncentrationen av klorofyll-a (chl-a) är en indikator på vilken trofinivå ett akvatiskt system har och används som ett mått på algbiomassa som påverkar övergödningen i akvatiska system. Höga koncentrationer av chl-a i sjöar kan indikera hög biomassa av fytoplankton och försämra kvalitén i vattnet eller eliminera viktiga funktionella grupper i ett ekosystem. Det är önskvärt att kunna prediktera chl-a koncentrationer för att förstå hur stor påverkan chl-a kan ha för olika scenarier i akvatiska system under längre perioder samt under säsongsvariationer. Flera modeller har tagits fram som predikterar årsvärden eller sommarvärden av chl-a koncentrationer och i dessa ingår totalfosfor, totalkväve eller en kombination av båda som inparametrar. Dessa modeller har hög prediktiv kraft men är inte utvecklade för att kunna utvärdera förändringar över längre perioder eller prediktera säsongsvariationer i ett system eftersom inparametrarna ofta är årsmedelvärden eller värden från andra specifika perioder. Modellerna är med andra ord begränsade till den domän som de togs fram för. Målet med denna avhandling var att komplettera dessa modeller med andra metoder och modeller vilket ger en bättre förståelse för hur chl-a koncentrationer i akvatiska system varierar, både i ett kortsiktigt och ett längre perspektiv. Resultaten visade att med en ny metod som kallas för Statistiskt meningsfull trend så har egentliga Östersjön inte haft någon förändring av chl-a koncentrationer under perioden 1975 till 2007 vilket motsäger tidigare resultat då p-värdet tas fram från en trendlinje av rådata. Det är möjligt att prediktera säsongsvariationer av median chl-a koncentrationer i sjöar från en bred geografisk domän med totalfosfor från sommar och latitud som inparametrar. Det är även möjligt att beräkna sannolikhetenav ett predikterat värde för olika månadsmedianer av chl-a koncentrationer med Markovkedjor eller ett direkt samband mellan två månader. Dessa resultat ger en reell förståelse för hur chl-a koncentrationer i akvatiska system varierar och kan användas till att validera hur olika åtgärder kan eller inte kan reducera problemet av de potentiellt skadliga algblomningarna.
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Storer, Timothy. "Ethology and production of freshwater crayfish in aquatic polysystems in Western Australia." Thesis, Curtin University, 2005. http://hdl.handle.net/20.500.11937/2442.
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Aquatic polyculture has been recognised as a potential way of increasing the costeffectiveness of farming marron (Cherax tenuimanus), as it can lower average costs of production, increase system yields, and reduce economic risks associated with monoculture operations. Polyculture also increases ecological stability and assists recycling processes, which can result in synergistic benefits to participating species. In aquaculture, this synergism can result in increased profitability through advanced growth rates and/or reduced feed input. However, many of the inherent advantages of aquatic polyculture rely on cohabitants occupying distinct ecological niches within the system. In Western Australia, opportunities to multi-crop aquatic species are limited by species choice due to low natural diversity and strict translocation policies. This creates a situation where available aquaculture species exhibit overlaps in occupied niches. Effects of this overlap can include direct predation, increased intraspecific conflict, and competition for resources such as shelter and food. Prior to this study, silver perch (Bidyanus bidyanus) were identified as a prime candidate for duoculture with marron, based on favourable schooling and feeding characteristics, and preliminary trials demonstrated commercial benefits, including synergistic growth advantages to marron. However, investigations also showed that silver perch will predate on both small and moulting crayfish under certain conditions, and that growth of silver perch was inhibited when held in cages to prevent predation. The work reported in this thesis was undertaken to address the niche overlap existing between marron and silver perch, and therefore assist the marron industry in Western Australia in implementing appropriate management strategies for diversification.Research focussed on investigating the ecological issues underlying interspecific interactions in marron polysystems, with the eventual aim of presenting information that could assist system managers in determining optimal conditions required to reduce antagonistic relationships and maximise synergism, ultimately leading to higher yields. Seven trials were conducted in three culture systems (54L aquaria, 250L aquaria and 720m2 experimental ponds) examining the ability of marron to detect, recognise and respond to a range of information cues (chemical, visual, tactile) from two potential predators (silver perch and Murray cod), with and without competition from conspecific and heterospecific crayfish (Cherax albidus). The ability of marron to interpret and respond appropriately to these variables was tested under a range of system-specific conditions, including stocking density, stocking size, shelter/habitat complexity, food availability, light intensity and life stage. Cage culture conditions were also examined to determine if the addition of shelter would mediate growth inhibition previously recorded, and to determine the desired stocking regime to return market sized fish in one growth season (8 months). Results from laboratory research and field-based trials did not support the free-range culture of marron and silver perch, even where turbidity and habitat complexity is high. Although both male and female marron (various sizes) demonstrated an ability to detect and differentiate between chemical and visual cues from potential predators, avoidance responses were only displayed upon attack from predators, or following predation of conspecifics; and avoidance strategies employed by marron were relatively ineffective.Although marron showed some capacity to recognise an impending predatory threat, high initial mortalities and growth inhibition due to reduced foraging, would greatly reduce system yields. In addition, intraspecific competition between marron is likely to increase as avoidance responses would lead to high relative densities within shelters. The lack of avoidance behaviour displayed by marron when only visual and chemical cues from predators are present strongly supports cage culture of silver perch in marron ponds. As marron did not appear to alter their general behaviour (e.g. foraging) based on cues associated with silver perch held in cages they stand to benefit from cohabitation. Field-trials examining the pond culture of marron and caged silver perch demonstrated synergistic growth advantages to marron, compared to monoculture, and also identified several system variables that appear to improve polyculture production. The addition of bank shelters (within 1m of waters edge) was suggested to give marron a competitive advantage when moulting, expressed through growth and survival. Survival of marron was also increased in caged polyculture ponds, compared to monoculture, most likely due to increased health status (due to improved recycling) and/ or increased habitat complexity owing to the presence of fish cages. Growth inhibition previously reported when silver perch are held in cages was mediated to some degree by cage shelters, which appeared to increase feeding behaviour, reduce general anxiety and resulted in increased growth. The introduction of advanced silver perch fingerlings in order to produce market-sized fish in one growth season was also supported. However, it is recommended that cage culture dynamics require further elucidation if silver perch are to be commercially successful as a stand-alone crop using this growout strategy.Significantly, the synergistic growth advantages experienced by marron when grown with fish demonstrate value from polyculture even if fish are not depended on as a secondary income. In this case, other species may also provide similar advantages, and a native candidate such as freshwater cobbler (Tandanus bostocki) would also redress problems associated with translocation laws restricting the use of silver perch in some areas of Western Australia. As no density effects were recorded in any of the trials conducted for either species, further investigation into increased system loads is required. In addition, as nutrient loads, and thus phytoplankton density, usually increases proportionately with pond biomass it is recommended that an additional herbivorous species, for example white eye mullet (Mugil cephalus), be examined in conjunction with increased density trials. Field research reported in this thesis was carried out in earthen ponds utilising remediated water from a acidified mine lake. Over a three-year period water quality parameters were maintained within optimal ranges for marron and silver perch, and survival and growth of both species was comparable to industry levels. These results validate the effectiveness of mine-water treatment technology; and accordingly, results support commercial viability of crayfish polyculture utilising remediated acid mine water. The large water resources offered by the numerous artificial lakes created from open cut mining has the potential to sustain a large successful aquaculture industry for Collie (Western Australia), and in other areas with extension of water treatment technology.The incorporation of caged silver perch into marron ponds not only takes advantage of the inherent economic and risk-spreading benefits from a diversified management strategy, but also incorporates a number of within-system benefits due to synergism between species. The ecological approach to aquatic polyculture research reported in this thesis has elucidated key communication factors underlying interactions within crayfish polysystems, which is critical to a knowledge-based approach to system management.
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Mongin, Sandrine. "Contributions to the study of the availability of metal ions in aquatic systems." Doctoral thesis, Universitat de Lleida, 2012. http://hdl.handle.net/10803/90839.
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La disponibilitat de metalls per part dels organismes no depèn únicament de la concentració total sinó també de l'especiació d'aquestes subtancias. En general, la disponibilitat de les espècies metàl•liques en medis naturals per a organismes està determinada per un conjunt d'esdeveniments encadenats on el equilibri representa només un cas particular de la situació dinàmica general.
Espècies poc definides químicament, com ara àcids húmics i fúlvics, actuen com a lligands de metalls i juguen un paper clau en la circulació i la determinació de les propietats ecotoxicològiques de les espècies metàl•liques en medis naturals. La polifuncionalitat dels àcids húmics i fúlvics és descrita en aquest estudi utilitzant mètodes termodinàmics i mecano-estadístics.
La tècnica Diffusive Gradients in Thin films (DGT) s'ha utilitzat per mesurar el flux disponible de metall en un sistema sintètic que conté complexos metàl•lics. La principal conclusió d'aquest estudi és que el disc de resina quelant dels sensors juga un paper clau en la determinació del grau de labilitat d'un complex mesurat amb aquesta tècnica. D'altra banda, a un pH baix, o concentració alta de lligand, es pot aconseguir l'equilibri entre la resina del sensor i el metall en el si de la dissolució, pertorbant l'acumulació lineal a temps de contacte relativament curts. Es presenta una anàlisi d'aquests fenòmens, així com la seva justificació mitjançant models teòrics.La disponibilidad de metales por parte de los organismos no depende únicamente de la concentración total sino también de la especiación de estas subtancias. En general, la disponibilidad de las especies metálicas en medios naturales hacia organismos está determinada por un conjunto de eventos encadenados cuyo equilibrio representa sólo un caso particular de la situación dinámica general. Especies poco definidas químicamente, tales como ácidos húmicos y fúlvicos, actúan como ligandos de metales y juegan un papel clave en la circulación y la determinación de las propiedades ecotoxicológicas de las especies metálicas en los medios naturales. La polifuncionalidad de los ácidos húmicos y fúlvicos es descrita en este estudio usando métodos termodinámicos y mecano-estadísticos. La técnica Diffusive Gradients in Thin films (DGT) se ha utilizado para medir el flujo disponible de metal en un sistema sintético que contiene complejos metálicos. La principal conclusión de este estudio es que el disco de resina quelatante de los sensores juega un papel clave en la determinación del grado de labilidad de un complejo medido esta técnica. Por otra parte, a un pH bajo, o a concentración alta de ligando, puede ser alcanzado el equilibrio entre la resina del sensor y el metal en el seno de la disolución, perturbando la acumulación lineal a tiempos de contacto relativamente cortos. Se presenta un análisis de estos fenómenos, así como su justificación mediante modelos teóricos.
Availability of metals for organisms does not depend only on the total metal concentration but also on speciation of these species. In general, the availability towards organisms is determined by a set of chained events whose equilibrium approach only represents a simplified limiting case of the general dynamic situation. Poorly defined species such as humic and fulvic acids, act as metal ligands and play a key role in the circulation and determination of the ecotoxicological properties of metal species in the natural media. Thermodynamic and statistical mechanics methods are here applied to describe the polyfunctionality of humic and fulvic acids. The Diffusive Gradients in Thin Films (DGT) has been used to measure the available metal flux in a synthetic system that contains metal complexes. A main conclusion of this study is that the chelating resin disc of the sensor plays a key role in determining the lability degree of a complex measured with DGT. Moreover, at relatively low pH, or in presence of high affinity ligands, the equilibrium with the bulk metal concentration can be approached in the sensor, disturbing linear accumulations at relatively short deployment times. Analysis of these phenomena and theoretical explanations are reported.
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Cabana, Gilbert. "A comparative study of food-web processes in aquatic systems using stable isotopes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/NQ29900.pdf.
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Ramjohn, Jamal Stephen. "The use of solar aquatic biological wastewater treatment systems in sustainable community design." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/MQ47650.pdf.
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Peel, Kate Elizabeth. "Studies into the Stable Isotope Geochemistry of Copper and Zinc in Aquatic Systems." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503795.
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Buratti, Sara <1981>. "Pharmaceutical residues in aquatic systems: mode of action and effects on mussel physiology." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3539/.
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Pharmaceutical residues contaminate aquatic ecosystems as a result of their widespread human and veterinary usage. Since continuously released and not efficiently removed, certain pharmaceuticals exhibit pseudo-persistence thus generating concerns for the health of aquatic wildlife.
This work aimed at assessing on mussels Mytilus galloprovincialis, under laboratory conditions, the effects of three pharmaceuticals, carbamazepine (antiepileptic), propranolol (β-blocker) and oxytetracycline (antibiotic), to evaluate if the human-based mode of action of these molecules is conserved in invertebrates. Furthermore, in the framework of the European MEECE Programme, mussels were exposed to oxytetracycline and copper at increasing temperatures, simulating variations due to climate changes.
The effects of these compounds were assessed evaluating a battery of biomarkers, the expression of HSP70 proteins and changes in cAMP-related parameters.
A decrease in lysosomal membrane stability, induction of oxidative stress, alterations of cAMP-dependent pathway and the induction of defense mechanisms were observed indicating the development of a stress syndrome, and a worsening in mussels health status. Data obtained in MEECE Programme confirmed that the toxicity of substances can be enhanced following changes in temperature. The alterations observed were obtained after exposure to pharmaceuticals at concentrations sometimes lower than those detected in the aquatic environment. Hence, further research is advisable regarding subtle effects of pharmaceuticals on non-target organisms.
Furthermore, results obtained during a research stay in the laboratories of Cádiz University (Spain) are presented. The project aimed at measuring possible effects of polluted sediments in Algeciras Bay (Spain) and in Cádiz Bay, by assessing different physiological parameters in caged crabs Carcinus maenas and clams Ruditapes decussatus exposed in situ for 28 days. The neutral red retention assay was adapted to these species and proved to be a sensitive screening tool for the assessment of sediment quality.