The rising number of antibiotic resistant bacteria (ARB) may introduce to the post antibiotic era because they cause a loss of the therapeutic potential of antibiotics. For many years the important role of the natural environment as reservoir and dissemination pathway for ARB and responsible genes has been largely overlooked. However, especially aquatic ecosystems provide optimal conditions for the antibiotic resistance (AR) evolution: first, aquatic ecosystems are frequently affected by anthropogenic activities that cause multiple pollutions for example with heavy metals, that potentially cause co-selection of antibiotic- and heavy metal resistance. Second, aquatic ecosystems feature a dissemination pathway between human populations and natural environments via the urban water cycle. Water cycles between human associated environments (e.g. house holds and clinics) via waste water through waste water treatment plants into natural ecosystems (e.g. water bodies) and back as drinking water after purification. Third, ecosystem internal biotic interactions such as competition between bacteria and predation by the natural consumers seem to impact AR evolution sustainably. The present doctoral thesis focuses on the impact of abiotic and biotic factors on the proliferation of AR and responsible genes in natural aquatic environments, with special emphasis on (i) heavy metal driven co-selection of antibiotic and heavy metal resistance and (ii) on the impact of competition and predation on the evolution of AR. In order to quantify the risk of heavy metal driven co-selection for AR spread, I provide a first risk assessment based on literature values of environmental heavy metal loadings and related AR. Additionally, I developed a limit value named minimum co-selective concentration (MCC), which is the lowest concentration of a heavy metal that can potentially cause coselection in nature. It turned out that Cu, Zn, Ni, Hg, and Cd are suspected to be the main co-selecting heavy metals in the aquatic environment. I further investigated heavy metal driven co-selection of AR in a river ecosystem, the Western Bug River (Ukraine). I found indications for co-selection of resistance to five antibiotics (ciprofloxacin, gentamicin, amikacin, tobramycin, and cefepime) and two metals (Ni and Cd) caused by Ni- and Cd-levels. Both metals exceed their MCC for water samples and Cd additionally in sediments. As a second focal point the present work emphasis on ecological interactions effecting AR evolution. Currently three possible effects of ecological interactions on AR spread are discussed. First, environmental antibiotic levels are rather low, however they might favour ARB due to a competitive advantage. The reason is that even sublethal antibiotic levels reduce the growth of sensitive bacteria while resistant cells remain unaffected by the antibiotic action. Second, predation by protozoa is believed to impact conjugation between prey bacteria (and thus the transfer of DNA and potential resistance genes) by keeping bacteria in a growing stage that favours conjugation. Third, in order to escape predation by protozoa, bacteria evolved grazing defence mechanisms such as the formation of inedible biofilms, which can feedback on the evolution of AR. With an ordinary differential equation model, I tested the effect of low antibiotic levels and losses (e.g. due to predation) on the proliferation of ARB in a modelled planktonic system. In case that the model contains the mechanism that conjugation frequencies are highest during exponential growth, I found that (i) (grazing) losses enhance conjugation frequencies between bacteria and that (ii) medium levels of antibiotics and (grazing) losses favour resistant cells in the competition to sensitive bacteria. Biofilms are thought to be \'hot spots\' for conjugation but some plasmids have lower conjugation frequencies in biofilms compared to planktonic systems. As a first step, in order to discover predation effects on plasmid spread in plankton - biofilm systems I investigated grazing resistance of bacteria in grazing experiments. Both plankton and biofilm phenotypes were consumed, when exposed to their specialized grazer (either plankton-feeder or biofilmfeeder), whereas the other phenotype remained grazing-resistant and thus became the dominant prey type. Both predators together effectively control planktonic and biofilm prey. With regards to the spread of AR-genes via conjugation, I speculate that the feeding preference of the present predator can affect the invasion success of resistance plasmids in planktonic - biofilm systems. For dynamic systems, I assume that dynamics of predator and prey traits (plankton vs. biofilm-feeder and biofilm vs. planktonic prey) will lead to dynamics of conjugation frequencies in planktonic or biofilm bacteria. I assume that conjugation events are more frequent in the dominant prey type (plankton or biofilm). However, other factors such as pili-type of the plasmid (short and rigid pili, prefers conjugation in biofilms or long and flexible pili, prefers conjugation in plankton) might additionally influence plasmid invasion success in plankton - biofilm morphotypes.

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In this PhD thesis, the utilisation of interactive simulation in a higher education e-learning classroom environment was explored and its effectiveness was experimentally evaluated by engaging university students in a classroom setting. Two case studies were carried out for the experimental evaluation of the proposed novel interactive simulation e-learning tool. In the first case study, the use of interactive agent-based simulation was demonstrated in teaching complex adaptive system concepts in the area of ecology to university students and its effectiveness was measured in a classroom environment. In a lab intervention using a novel interactive agent-based simulation (built in NetLogo). For the purpose of teaching complex adaptive systems such as the concept of spatially-explicit predator prey interaction to undergraduate and postgraduate students in the University of Stirling. The effectiveness of using the interactive simulation was investigated by using the NetLogo software and compared with non-interactive simulation built using R programming language. The experimental evaluation was carried out using a total of 38 students. Results of this case study demonstrates that the students found interactive agent-based simulation to be more engaging, effective and user friendly as compare to the non-interactive simulation. In the second case study, a novel interactive simulation game was developed (in NetLogo) and its effectiveness in teaching and learning of complex concepts in the field of marine ecology was demonstrated. This case study makes a twofold contribution. Firstly, the presentation of a novel interactive simulation game, developed specifically for use in undergraduate and postgraduate courses in the area of marine ecology. This novel interactive simulation game is designed to help learners to explore a mathematical model of fishery population growth and understand the principles for sustainable fisheries. Secondly, the comparison of two different methods of using the interactive simulation game within the classroom was investigated: learning from active exploration of the interactive simulation game compared with learning from an expert demonstration of the interactive simulation game. The case study demonstrated the effectiveness of learning from passive viewing of an expert demonstration of the interactive simulation game over learning from active exploration of the interactive simulation game without expert guidance, for teaching complex concepts sustainable fishery management. A mixed methods study design was used, using both quantitative and qualitative methods to compare the learning effectiveness of the two approaches, and the students’ preferences. The investigation was carried out by running interventions with a mixture of undergraduate and postgraduate students from the University of Stirling in a classroom environment. A total of 74 participants were recruited from undergraduate and postgraduate level for both case studies. This thesis demonstrated through two case studies effectiveness of the proposed novel interactive simulation in university e-learning classroom environment.

Predators can have large effects on prey populations and on the structure and function of communities. In addition to direct consumption of prey, predators often cause prey to alter their foraging behavior, habitat selection, and morphology. These non-lethal effects of predators can propagate to multiple trophic levels and often exert equal or larger effects upon communities than those of direct consumption. For non-lethal predatory effects to occur, prey must detect and respond to predation risk. While the importance of information transfer in this process has been realized, few studies explore how prey responses are influenced by predator characteristics and environmental conditions that influence the transmission of cues indicative of predation risk. In this dissertation I investigate factors that influence how a single prey species evaluates and responds to predation risk. Here, I examined: 1) the type and nature of cues prey use to evaluate predator risk; 2) how predator identity, predator diet, and the relative risk of predators influence prey response to predation risk; 3) how hydrodynamic conditions influence the delivery of predator cues; 4) how biogeographic trends in predator distribution influence prey response to predation risk; and 5) how genetic structure might vary according to prey geographic location and habitat. To address these questions, I used a common intertidal model system consisting of the rocky intertidal whelk Nucella lapillus (Linnaeus, 1758) and a suite of its predators, the native rock crab Cancer irroratus (Say, 1817), Jonah crab Cancer borealis (Stimpson, 1859), and the invasive green crab Carcinus maenas (Linnaeus, 1758). Nucella use chemical cues emanating from their most common predator (Carcinus maenas) and crushed conspecifics to evaluate predation risk. Nucella from different habitats experience different levels of predation risk, and Nucella from habitats with high levels of predation had larger antipredatory responses to predator risk cues than Nucella that experienced less predation. These chemical cues indicative of predation risk are influenced by hydrodynamic conditions, and Nucella have the strongest anti-predatory response in flow velocities of u= ~4- 8 cm s^-1. Furthermore, Nucella from geographic regions where green crabs are historically absent did not elicit anti-predatory responses, while Nucella from regions where green crabs are common frequently responded. Findings from my dissertation research demonstrate that prey detection and response to predation risk is highly dependent upon predator identity, predator diet, environmental forces, and biogeographic patterns in predator and prey distributions.

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<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, härtill 6 uppsatser.</p> / digitalisering@umu

I investigated Lake Sturgeon (Acipenser fulvescens) foraging and anti-predator behaviour. My goals were to understand: (1) The role of environmental change on foraging and anti-predator behaviour trade-offs. (2) The relative cost/benefit trade-off between escape behaviour and cover-seeking behaviour. (3) How development of several independent morphological traits affects anti-predator behaviours. I used simulated river mesocosms to study Lake Sturgeon behavioural ecology under controlled conditions. I found: (1) Foraging intensity was significantly higher during the night than the day as well as in turbid environments versus clear environments, indicating that decreased turbidity alone, may in part drive anti-predator behaviour and constrain foraging activity. (2) In high-risk clear-water environments, Lake Sturgeon responded to danger by evoking an escape response and seeking cover in rocky microhabitats. However, in low-risk turbid environments, Lake Sturgeon responded to danger by seeking cover in rocky microhabitats, but not fleeing to a significant degree. Cover-seeking behaviour may therefore be a relatively low-cost/high-benefit anti-predator strategy. (3) Strong evidence for trait co-dependence between escape responses and body size, where larger fish were able to elicit stronger escape responses. I also found that cover-seeking behaviour exhibited a complex multi-tiered relationship, representing a mixture of trait compensation and trait co-specialization that is dependent on specific combinations of morphological traits. These findings are important because they help us understand: (1) The degree to which anti-predator behaviour can be influenced by changing environmental conditions. (2) The relative cost/benefit trade-off between two common anti-predator behaviours. (3) How behaviour and morphology interact in species with a complex anti-predator phenotype.

Understanding the ecology of an organism is fundamental for defining conservation and management priorities for wildlife and natural ecosystems. The most basic ecological framework identifies the key components of an organism's habitat, and the scale for measuring the quality of those features. How these core needs are expressed and vary in the surrounding ecosystem changes over time and space. In marine systems, the physical environment has few strict boundaries, and variations regularly occur on a scale from days to decades. The dynamic and patchy nature of marine habitat makes defining the ecological roles of an animal difficult, even where baseline data exists. In this study I analyze long term field records on the ecological interactions between foraging gray whales (Eschrichtius robustus), and their mysid prey (Family mysidae) in Clayoquot Sound, B.C. By looking at spatial and temporal shifts at both trophic levels, I measure foraging responses and requirements, and assess prey resource availability and resiliency in the marine environment at a series of scales. Appreciation for bottom-up and topdown trophic interactions provides the foundation for identifying natural variability in marine habitat, and a baseline for conservation measures that seek to use marine predators as a barometer of broader ecosystem health.

Research Doctorate - Doctor of Philosophy (PhD) / The original contribution of this thesis is to demonstrate the use of a generalised and parsimonious approach to building individual-based computer models of ecological systems with the objective of advancing our mechanistic understanding of these systems. Two models are presented; the first, a model of predator-prey interaction, produces the expected non-linear dynamics and illustrates the importance of the timing of variable updating and individual variation for the persistence of the populations. This model is applied to two near-exclusive, cycling predator-prey systems, those of the Canadian lynx and snowshoe hare and the Fennoscandian mustelid predators and their microtine prey. The reproduction of the patterns found in the empirical data of these systems by the model suggests that the underlying mechanism of these predator-prey systems may be more simple than is suggested by other more complex models reported in the literature. The second model describes a system similar to that of a grazing herbivore in a two-dimensional space. The emergence of complex behaviour resulting from the use of space in the model, including metapopulation-like local extinction and re-population and the effects of corridors and edge qualities on the species are demonstrated. The inclusion of a graphical display of the two-dimensional space in the computer interface to the model reveals important details of system behaviour not evident in the population means, including herding behaviour. The latter is dependent on herbivore mobility and the re-growth of resources in an heterogeneous environment, and emerges in the absence of social behaviour. The problem of detecting herding behaviour automatically is addressed, including the development of qualitative and quantitative definitions of herding in the model.