Florida's estuaries support a wide range of species yet little is known about tracemetal cycling among members of this important ecosystem. To examine the flow of trace metals through the Tampa Bay estuary, four fish species representing different trophic levels were analyzed for copper (Cu), zinc (Zn) and stable isotopes of carbon (C) and nitrogen (N). Species selected were the striped mullet (Mugil cephalus), tidewater mojarra (Eucinostomus harengulus), bay anchovy (Anchoa mitchilli), and sand seatrout (Cynoscion arenarius). Juvenile fish were collected from the Alafia, Hillsborough, Palm, and Little Manatee Rivers. Adults were collected from Tampa Bay. Combinations of trace metal and stable isotope analyses were used to evaluate geographic variability in trace metal concentrations among locations in Tampa Bay and to shed light on trophic pathways that lead to trace metal accumulation. In juvenile mullet, significant trends were found between Zn concentrations, stable isotope ratios, and standard length. Animals of the smallest size classes carry greater concentrations of zinc in their tissues and have distinct stable isotope ratios that reflect their recent life history as offshore planktivorous larvae. Interestingly, the ratio of Zn:Cu concentrations was highly conserved. While species-specific differences were observed, relatively small Zn:Cu variations suggest a possible bioregulatory mechanism that maintains an optimal Zn:Cu ratio even in the presence of elevated absolute metal concentrations. Stable isotope ratios proved to be an effective tracer of ontogenetic changes in fish diet and habitat. Carbon and nitrogen stable isotope analyses revealed that trophic relations between species are established very early in an organism's life history. The bay anchovy, a major prey item of the sand seatrout, has δ15N values very similar to this predator. Although trophic linkages between trace metals and stable isotopes proved difficult to interpret, the relation between zinc concentrations and δ¹³C values suggested that trace metal concentrations are highest in animals that utilize food webs based on terrestrial carbon.

[Formulae and special characters can not be reproduced here. Please see the pdf version of the Abstract for an accurate reproduction.] The thesis provides a comprehensive study on the behaviour of sand with a small amount of fines [i.e.1/3 plastic fines and 2/3 non-plastic fines]. The work is carried out experimentally under axi-symmetric conditions using the triaxial apparatus. Conventional drained triaxial tests are conducted on isotropic consolidated specimens and all the tests indicate that sand with fines does not manifest any unusual behaviour under drained conditions. However in undrained shearing the so-called ???reverse behaviour??? is noted. The study demonstrates that the reverse behaviour conforms to the critical state framework because significant changes in the position and geometry of the critical state [CS] and isotropic consolidation [IL] lines are caused by the presence of fines. These changes cannot be adequately modelled by the intergranular void ratio as proposed by Thevanayagam and Mohan (2000). This study also demonstrates that the original state parameter [special character] as proposed by Been and Jefferies (1985) is not an adequate parameter to predict the undrained behaviour trend. A new parameter termed ???modified state parameter??? [special character] is proposed to account for the combined effects of density and confining pressure. The suitability of the modified state parameter to characterise the response of parent sand and sand with fines is assessed for a range of void ratios and confining pressures. The effect of drained stress history is an important factor affecting the subsequent undrained response. Drained pre-shearing to failure is found to improve considerably the subsequent undrained response to the extent that liquefaction may not occur. Different drained pre-shearing histories have different effects on the undrained response. However in these tests [special character] has limitations in quantifying the subsequent undrained stress-strain response. Hence, a new framework of ???yielding parameter??? [special character] extends the capability of [special character] and additional data is presented to demonstrate the suitability of this concept. The implementation of [special character] depends on whether the previous stress state reached during the stress history is below or at failure. The effects of drained pre-shearing on the position and movement of failure surface are investigated. It is found that drained pre-shearing to failure at larger confining pressures has the effect of shifting upwards part of the drained failure surface. The shift at larger stress ratios [special character] may be described in terms of dilatancy and modified state parameter at failure. The so-called strain path tests are conducted to study the influence of strain increment ratio on the deformation behaviour of sand with fines. It is found that the value of [special character] has significant effects on the stress-strain behaviour. Along negative [special character] paths the soil strain softens in the form of decreasing the shear resistance before reaching the failure state. In contrast, along positive [special character] paths the soil strain hardens to an asymptotic stress ratio. The asymptotic stress ratio decreases with increasing [special character] along a linear relationship. The framework of [special character] cannot quantify the stress-strain response along positive and negative strain paths. Consequently an ???instability parameter??? [special character] is proposed to extend the capabilities of [special character] and the reliability of this parameter is further assessed. The behaviour along a range of positive and negative [special character] paths is investigated on pre-sheared specimens. In negative [special character] the effective stress paths reach a surface located higher than the monotonic failure surface on which they trace downward towards the origin of stress space. The results indicate this surface may be the same as the drained failure envelope which has been shifted as a result of drained pre-shearing. In positive [special character] paths a large improvement is noted in both the strength and stiffness of the soil. Note The parameters [special character] and [special character] are all generalisations of [special character] so that the behaviour under complex conditions can be characterised.

The Central Queensland University developed an on-site wastewater treatment and reuse technology. Septic tanks were used for primary treatment and the discharged effluent was then pumped though a series of contained channels. The channels were designed to be a modified evapotranspiration trench; they were comprised of an aggregate layer and a soil layer in which were planted a variety of plants. The aggregate and the soil provided physical filtration, the microorganisms within the effluent, aggregate and soil provided nutrient reuse and transformation and the plants also used the nutrients and reused the treated effluent through evapotranspiration. Any effluent that was not transpired was returned to a holding tank and pumped through the evapotranspiration again. The treatment technology was assessed in relation to its ability to treat effluent in a sustainable manner. The water and soil was examined for concentrations of nutrients, heavy metals, salts, sodium, and organic carbon %. The pH, temperature and number of colony forming units of certain microorganism potential pathogens were also inspected in the soil and the water. The plants grown within the evapotranspiration channels were assessed in regards to their health, water usage, and in some cases potential pathogens on fruit. The infrastructure that was used to construct the wastewater treatment and reuse system was also evaluated in regards to reliability and maintenance. Certain limiting factors, in particular sodicity and salinity were identified, but the trial was successful and a sustainable form of on-site wastewater treatment and reuse technology was developed.

Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to study the interactions among invasive ecosystem engineers, physical features, and biological communities, because interactions among vegetation, sediment, and fluids within biophysical feedbacks create and modify distinct physical features. Further, these systems provide important ecosystem services including coastal protection afforded by their natural features. In this dissertation, I investigate the interactions and feedbacks among sand-binding beach grass species (a native, Elymus mollis (Trin.), and two non-natives, Ammophila arenaria (L.) Link and A. breviligulata Fernald), sediment supply, and dune shape along the U.S. Pacific Northwest coast. Dunes dominated by A. arenaria tend to be taller and narrower compared to the shorter, wider dunes dominated by A. breviligulata. These patterns suggest an ecological control on dune shape, and thus, coastal vulnerability to overtopping waves. I investigate the causes and consequences of these patterns with experiments, field observations, and modeling. Specifically, I investigate the relative roles of vegetation and sediment supply in shaping coastal dunes over inter-annual and multi-decadal time scales (Chapter 2), characterize a biophysical feedback between beach grass species growth habit and sediment supply (Chapter 3), uncover the mechanisms leading to beach grass coexistence and whether A. breviligulata can invade and dominate new sections of coastline (Chapter 4), and examine the non-target effects resulting from management actions that remove Ammophila for the recovery of the threatened Western Snowy plover (Charadrius alexandrinus nivosus) (Chapter 5). I found that vegetation and sediment supply play important roles in dune shape changes across inter-annual and multi-decadal time scales (Chapter 2). I determined that a biophysical feedback between the beach grass growth habits and sediment supply results in species-specific differences in sand capture ability, and thus, is a likely explanation for differences in dune shape (Chapter 3). I found that all three beach grass species can coexist across different sediment deposition rates, and that this coexistence is largely mediated by positive direct and indirect species interactions. I further determined that A. breviligulata is capable of invading and dominating the beach grass community in regions where it is currently absent (Chapter 4). Combined, these findings indicate that A. breviligulata is an inferior dune building species as compared to A. arenaria, and suggest that in combination with sediment supply gradients, these species differences ultimately lead to differences in dune shape. Potential further invasions of A. breviligulata into southern regions of the Pacific Northwest may diminish the coastal protection ability of dunes currently dominated by A. arenaria, but this effect could be moderated by the predicted near co-dominance of A. arenaria in these lower sediment supply conditions. Finally, I found that the techniques used to remove Ammophila for plover recovery have unintended consequences for the native and endemic dune plant communities, and disrupt the natural disturbance regime of shifting sand. A whole-ecosystem restoration focus would be an improvement over the target-species approach, as it would promote the return of the natural disturbance regime, which in turn, would help recover the native biological community. The findings from this dissertation research provide a robust knowledge base that can guide further investigations of biological and physical changes to the coastal dunes, can help improve the management of dune ecosystem services and the restoration of native communities, and can help anticipate the impacts of future beach grass invasions and climate change induced changes to the coast. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Sept. 22, 2011 - March 22, 2012

<p><font face="TimesNewRomanPSMT"> <p align="left">Natural radioactivity studies have been carried out to study the textural characteristics, heavy mineral composition, provenance, sediment transport, and depositional environment of beach placer deposits. The naturally occurring radionuclides such as properties of beach sands, which reflect the geological characteristics such as transport and sorting processes and the depositional environment. The present work focuses on the radiometric characteristics of beach sand deposits along the west coastof South Africa. Beach sands samples were collected at the Melkbosstrand (MBS) and Ouskip (OSK) beach. The activity concentrations of these radionuclides were determined by high-resolution gamma-ray spectrometry using a high-purity germanium (HPGe) detector in a low-background configuration.</p> </font></p>

No description available.

Natural and sexual selection and sexual conflict are forces shaping the evolution of reproductive behaviour, while constrained by factors like environment, physiology and life-history trade-offs. Parental care is costly both in terms of time and energy. In fish, filial cannibalism is a strategy for caring males to compensate for some of the energy loss. Human impact like eutrophication also alters the basics for animals living in that environment. It is fundamental to any species to adjust its behaviour to a changing environment. Studying sand goby males, I found trade-offs both regarding parental care allocations, like ventilation vs. predator defence, and investment in present vs. future reproductive success. Paternal sand gobies exposed to water with low oxygen levels increased their fanning effort but did not compensate by eating more eggs, even though an increased current parental effort should affect future reproductive success negatively. Investigating if patterns of filial cannibalism change with time of season, I found no correlation. Theory predicts that it should pay more to eat eggs early, when future mating potential is higher than late in the season. However, as early hatching fry are likely to gain higher fitness through larger size the next breeding season, this may provide an opposing selection pressure. In species with male care the only way a female can affect the level of post-spawning care is by choosing a good mate. A female preference to spawn in nests that already contain eggs of other females has been interpreted as a means to avoid filial cannibalism through a dilution effect or to decrease the costs of search time. Yet, in my study females did not avoid filial cannibalism by preferring large clutches to small ones. Oxygenation of the eggs might be a key factor, since both large and small females preferred spawning in nests with small clutches. Thus, as in most animals, trade-offs clearly govern the reproductive behaviour of sand gobies.

Slow sand filtration is a proven and sustainable technology for drinking water treatment in small communities. The process, however, is sensitive to lower water temperatures that can lead to decreased biological treatment, and high raw water turbidity levels that can lead to premature clogging of the filter and frequent cleaning requirements, resulting in increased risk of pathogen breakthrough. Multistage filtration, consisting of roughing filtration followed by slow sand filtration, can overcome these treatment limitations and provide a robust treatment alternative for surface water sources of variable water quality in northern climates, which typically experience water temperatures ranging down to 2&deg;C. Prior to this study, however, multistage filtration had yet to be systematically challenged in colder climates, including testing of its performance under increased hydraulic loadings and elevated influent turbidity together with cold water conditions. The primary goal of this research was to demonstrate the reliability of multistage filtration for small communities in northern climates with reference to the Ontario Safe Drinking Water Act. In this research, testing was conducted on two different pilot multistage filtration systems and fed with water from the Grand River, a municipally and agriculturally impacted river in Southern Ontario. One system featured pre-ozonation and post-granular activated carbon (GAC) stages, and shallower bed depths in the roughing filter and slow sand filter. The other system featured deeper bed depths in the roughing filter and slow sand filter, two parallel roughing filters of different design for comparison, and a second stage of slow sand filtration for increased robustness. Removal of turbidity, total coliforms, and fecal coliforms under a range of influent turbidities (1 to >100 NTU), water temperatures (~2 to 20&deg;C), and hydraulic loading rates (0. 2 to 0. 8 m/h) were investigated. In addition, the slow sand filters in each pilot system were challenged with high concentrations (~10⁶ oocyst/L) of inactivated <i>Cryptosporidium parvum</i> oocysts. The performance of both pilot multistage filtration systems was highly dependent on the biological maturity of the system and its hydraulic loading rate. In a less mature system operating in cold water conditions (<5&deg;C), effluent turbidity was mostly below 0. 5 NTU during periods of stable influent turbidity (no runoff events) and a hydraulic loading of 0. 4 m/h, however, runoff events of high influent turbidity (>50 NTU), increased hydraulic loadings (0. 6 m/h), and filter cleaning occasionally resulted in effluent turbidity above 1 NTU. Furthermore, in a less mature system operating during runoff events of high turbidity, reducing the hydraulic loading rate to 0. 2 m/h was important for achieving effluent turbidity below 1 NTU. However, in a more mature system operating in warm water conditions (19-22&deg;C), effluent turbidity was consistently below 0. 3 NTU at a hydraulic loading rate of 0. 4 m/h, and below 0. 5 NTU at 0. 8 m/h, despite numerous events of high influent turbidity (>25 NTU). It remains to be seen whether this performance could be sustained in colder water temperatures with a fully mature filter. Removal of coliform bacteria was occasionally incomplete in a less mature multistage system, whereas, in a more mature system operating in warm water conditions (>9&deg;C), removal was complete in all measurements. Furthermore, the average removal of <i>Cryptosporidium</i> was greater than 2. 5 logs in both systems (with hydraulic loading rates ranging from 0. 4 to 0. 8 m/h) and improved with increased filter maturity. Each individual stage of the multistage system was an important treatment barrier in the overall process of turbidity and pathogen removal. The roughing filter was not only important for protecting the slow sand filter from solids loading and increasing its run length, but was also a significant contributor to coliform removal when the system was less mature. Removal of turbidity was significantly improved when the roughing filter was more mature, suggesting that biological treatment was an important treatment mechanism in the roughing filter. Although pre-ozonation was used mainly for the removal of organic carbon and colour, it achieved complete removal of coliform bacteria and was also suspected to be important for enhanced removal of turbidity. The second slow sand filter in series provided additional robustness to the process by reducing effluent turbidity to below 1 NTU during cold water runoff events of high turbidity and increased hydraulic loadings (0. 6 m/h), while achieving effluent below 0. 3 NTU during normal periods of operation. It also provided additional removals of coliforms under challenging operating conditions, and contributed an additional average removal of <i>Cryptosporidium</i> of 0. 8 logs, which resulted in cumulative removal of 3. 7 logs, approximately 1 log greater than all the other challenge tests. Collectively, the entire multistage system performed well with water temperatures ranging down to 2&deg;C, limited filter maturity, elevated raw water turbidities, and increased hydraulic loading rates. Its ability to meet the current Ontario turbidity regulations and greater than 2 log removal of <i>Cryptosporidium</i> over a range of operating conditions, with little or no process adjustment, is a testament to the robustness and minimal maintenance requirements of the process, which are desirable attributes for small water systems that are often located in rural areas. While this research demonstrated the performance of multistage filtration using pilot scale testing, it is important to note that full-scale plants tend to produce significantly better results than pilot facilities, due to long term biological maturation of the system. Overall, multistage filtration is a sustainable and cost-effective technology that, through this research, appears to be a safe, reliable, and robust treatment alternative for small and non-municipal water systems in North America and the developing world. Further, based on its performance with challenging influent water quality and cold water conditions, multistage filtration holds particular promise for small communities in northern climates that are required to meet safe drinking water regulations, but are dependent on surface water sources of variable water quality and temperatures.

Östby waterworks in the community of Kramfors has since 2003 had problems of fast clogging of the slow sand filters. As the clogging appears more often, they must be cleaned more frequently which has made the drinking water preparation difficult. Wintertime it has sometimes been impossible to clean the filters which has led to their closing and this has influenced the water quality negatively. The waterworks is a surface waterworks which takes its raw water from the lake Sjöbysjön. The water is flocculated and filtered in a contact filter with the flocculent EKOFLOCK 91. Thereafter it is alkalinized before it reaches the outdoors placed slow sand filters. After the filters the water is alkalinized and disinfected before it reaches the customers. This thesis work has looked into which factors influence the clogging and trials have been made in order to optimize the waterworks and thereby reduce the clogging. The raw water has been studied with aspect to biology and chemistry, the filtered water has been studied with aspect to chemistry and also the pressures in the slow sand filters have been studied. The colour of the raw water from Sjöbysjön and its catchment area has increased since the beginning of the 90-ies and also the bio volume has increased in the lake. The contents of aluminium before the slow sand filters are far higher than the contents after, which leads to the conclusion that aluminium is accumulated in the filters. The differential pressure over the sand bed increases with time after a cleaning. This indicates an accumulation of particles which increases with the load. Observations of the filter surface before cleaning showed that it was covered by a brown, jelly-like film. The internal resistance in the filter beds increases successively after a cleaning and one month after cleaning it is highest in the upper part of the sand bed. All this points to that flocculated aluminium is gathered in the slow sand filters, on the surface, causing clogging. While the thesis work has been going on a process of alkalinizing before the contact filters has been reengaged and this has influenced the flocking of organic materials. When raising the pH the dose of flocculent was increased and this combined increased the amount of flocculated material. The contact filters could not bear this increased amount of flock load but showed instead a breakthrough. In a few lab scale trials the flocking pH was varied as well as the dose flocculent to the raw water and after this the water was filtrated. A tendency was seen that the separation of aluminium, colour and turbidity increased with increasing pH and dose flocculent. At the pH 6.2 and the chemical dose of 60 g/m3 the content of aluminium, the colour and the turbidity showed the lowest values in the filtrate. / Vattenverket i Östby, Kramfors kommun, har sedan 2003 haft problem med för snabba igensättningar i långsamfiltren. Ju oftare de sätter igen desto mer frekvent måste de rensas vilket har försvårat dricksvattenberedningen. Vintertid har rensningar ibland inte kunnat utföras och långsamfiltren har därför stängts av vilket har påverkat vattenkvaliteten negativt. Verket är ett ytvattenverk som tar sitt råvatten från Sjöbysjön. Vattnet flockas och filtreras i kontaktfilter med fällningskemikalien EKOFLOCK 91. Därefter mellanalkaliniseras det innan det går till de utomhus placerade långsamfiltren. Efter långsamfiltren efteralkaliniseras och desinficeras det innan det når konsumenterna. I detta examensarbete har faktorer som påverkar igensättningarna undersökts och försök har också gjorts för att optimera driften och därmed minska igensättningarna. Råvattnet har undersökts avseende dess biologi och kemi, filtraten i verken har undersökts med avseende på deras kemi och tryckbildningar i långsamfiltren har studerats. Färgtalet i råvattentäkten Sjöbysjön och dess tillrinningsområde har ökat sedan början av 90- talet och dessutom har biovolymen i sjön ökat. Halterna aluminium före långsamfiltren är mycket högre än halterna efter, vilket antyder att aluminium ansamlas i filtren. Differentialtrycket över sandbädden ökar med tiden efter en rensning. Detta tyder på en ansamling av partiklar som ökar med belastningen. Observationer av filterytan innan rensning visade att den täcktes av en brun geléaktig hinna. Motståndet i filtren ökar successivt efter en rensning och är en månad efter rensning störst i den övre delen av sandbädden. Allt detta pekar på att aluminiumflock ansamlas i långsamfiltren, på ytan, och orsakar igensättningarna. Under examensarbetets gång har en föralkalinisering återinförts i vattenverkets process och den har påverkat fällningen av det organiska materialet. Då pH höjts har också dosen fällningskemikalie ökats vilket har ökat mängden flock. Denna ökade flockmängd har kontaktfiltren inte kunnat bära utan istället släppt igenom. I några försök i labbskala varierades fällnings-pH och dos fällningskemikalie till råvatten med en efterföljande filtrering. Tendenser som kunde ses var att avskiljningen av aluminium, färg och turbiditet ökade med ökat pH och ökad dos fällningskemikalie. Vid pH 6,2 och kemikaliedos på 60 g/m3 var aluminiumhalterna, färgen och turbiditeten som minst i filtratet.

Slow sand filtration is a proven and sustainable technology for drinking water treatment in small communities. The process, however, is sensitive to lower water temperatures that can lead to decreased biological treatment, and high raw water turbidity levels that can lead to premature clogging of the filter and frequent cleaning requirements, resulting in increased risk of pathogen breakthrough. Multistage filtration, consisting of roughing filtration followed by slow sand filtration, can overcome these treatment limitations and provide a robust treatment alternative for surface water sources of variable water quality in northern climates, which typically experience water temperatures ranging down to 2&deg;C. Prior to this study, however, multistage filtration had yet to be systematically challenged in colder climates, including testing of its performance under increased hydraulic loadings and elevated influent turbidity together with cold water conditions. The primary goal of this research was to demonstrate the reliability of multistage filtration for small communities in northern climates with reference to the Ontario Safe Drinking Water Act. In this research, testing was conducted on two different pilot multistage filtration systems and fed with water from the Grand River, a municipally and agriculturally impacted river in Southern Ontario. One system featured pre-ozonation and post-granular activated carbon (GAC) stages, and shallower bed depths in the roughing filter and slow sand filter. The other system featured deeper bed depths in the roughing filter and slow sand filter, two parallel roughing filters of different design for comparison, and a second stage of slow sand filtration for increased robustness. Removal of turbidity, total coliforms, and fecal coliforms under a range of influent turbidities (1 to >100 NTU), water temperatures (~2 to 20&deg;C), and hydraulic loading rates (0. 2 to 0. 8 m/h) were investigated. In addition, the slow sand filters in each pilot system were challenged with high concentrations (~10⁶ oocyst/L) of inactivated <i>Cryptosporidium parvum</i> oocysts. The performance of both pilot multistage filtration systems was highly dependent on the biological maturity of the system and its hydraulic loading rate. In a less mature system operating in cold water conditions (<5&deg;C), effluent turbidity was mostly below 0. 5 NTU during periods of stable influent turbidity (no runoff events) and a hydraulic loading of 0. 4 m/h, however, runoff events of high influent turbidity (>50 NTU), increased hydraulic loadings (0. 6 m/h), and filter cleaning occasionally resulted in effluent turbidity above 1 NTU. Furthermore, in a less mature system operating during runoff events of high turbidity, reducing the hydraulic loading rate to 0. 2 m/h was important for achieving effluent turbidity below 1 NTU. However, in a more mature system operating in warm water conditions (19-22&deg;C), effluent turbidity was consistently below 0. 3 NTU at a hydraulic loading rate of 0. 4 m/h, and below 0. 5 NTU at 0. 8 m/h, despite numerous events of high influent turbidity (>25 NTU). It remains to be seen whether this performance could be sustained in colder water temperatures with a fully mature filter. Removal of coliform bacteria was occasionally incomplete in a less mature multistage system, whereas, in a more mature system operating in warm water conditions (>9&deg;C), removal was complete in all measurements. Furthermore, the average removal of <i>Cryptosporidium</i> was greater than 2. 5 logs in both systems (with hydraulic loading rates ranging from 0. 4 to 0. 8 m/h) and improved with increased filter maturity. Each individual stage of the multistage system was an important treatment barrier in the overall process of turbidity and pathogen removal. The roughing filter was not only important for protecting the slow sand filter from solids loading and increasing its run length, but was also a significant contributor to coliform removal when the system was less mature. Removal of turbidity was significantly improved when the roughing filter was more mature, suggesting that biological treatment was an important treatment mechanism in the roughing filter. Although pre-ozonation was used mainly for the removal of organic carbon and colour, it achieved complete removal of coliform bacteria and was also suspected to be important for enhanced removal of turbidity. The second slow sand filter in series provided additional robustness to the process by reducing effluent turbidity to below 1 NTU during cold water runoff events of high turbidity and increased hydraulic loadings (0. 6 m/h), while achieving effluent below 0. 3 NTU during normal periods of operation. It also provided additional removals of coliforms under challenging operating conditions, and contributed an additional average removal of <i>Cryptosporidium</i> of 0. 8 logs, which resulted in cumulative removal of 3. 7 logs, approximately 1 log greater than all the other challenge tests. Collectively, the entire multistage system performed well with water temperatures ranging down to 2&deg;C, limited filter maturity, elevated raw water turbidities, and increased hydraulic loading rates. Its ability to meet the current Ontario turbidity regulations and greater than 2 log removal of <i>Cryptosporidium</i> over a range of operating conditions, with little or no process adjustment, is a testament to the robustness and minimal maintenance requirements of the process, which are desirable attributes for small water systems that are often located in rural areas. While this research demonstrated the performance of multistage filtration using pilot scale testing, it is important to note that full-scale plants tend to produce significantly better results than pilot facilities, due to long term biological maturation of the system. Overall, multistage filtration is a sustainable and cost-effective technology that, through this research, appears to be a safe, reliable, and robust treatment alternative for small and non-municipal water systems in North America and the developing world. Further, based on its performance with challenging influent water quality and cold water conditions, multistage filtration holds particular promise for small communities in northern climates that are required to meet safe drinking water regulations, but are dependent on surface water sources of variable water quality and temperatures.