Dissertations / Theses on the topic 'Non-native species'

Across the globe, invasive non-native species (INNS) are a major ecological and economic problem with freshwater environments particularly susceptible to their impacts. Preventing their introduction and spread is considered the most environmentally desirable and cost-effective form of management by the Convention on Biological Diversity, and is advocated in new EU INNS legislation which comes into force in 2015. Biosecurity – a term describing actions taken to prevent the introduction and spread of unwanted organisms – is central to this preventative approach. This PhD combines ecological and social research to identify human-mediated pathways for the spread of INNS in freshwater environments; to examine the effectiveness of biosecurity measures; and to identify how biosecurity awareness and compliance could be improved. Initial questionnaire research revealed that recreational water users in the UK are potential vectors for INNS due to their movement patterns and low biosecurity compliance. A survival experiment showed that many aquatic INNS threatening the UK can survive in damp conditions for 16 days but demonstrated that hot water (45˚C, 15 mins) is an effective biosecurity control measure, causing 99% mortality in many high risk INNS within 1 hour. As a result of a long-term biosecurity campaign, New Zealand water users had high biosecurity awareness and compliance compared to the UK. The development of regional partnerships and the support of national legislation were key components of the country’s streamlined approach to biosecurity. Invasive non-native crayfish had a significantly lower diversity and prevalence of parasites than native crayfish in the UK, supporting the concept of enemy release. Finally, a global meta-analysis revealed that recreational activities also act as vectors for the introduction of INNS in terrestrial and marine environments and require biosecurity measures of a similar magnitude. The results provide an evidence base from which to develop freshwater biosecurity strategies in the UK and wider Europe.

Les aires protégées sont des éléments clés de la stratégie mondiale de conservation de la biodiversité, en visant à préserver les espèces, les habitats et les écosystèmes. La mondialisation a entraîné une augmentation des introductions d'espèces en dehors de leur aire de répartition naturelle. Dans leur nouvel environnement, certaines de ces espèces non indigènes ont le potentiel d’affecter les écosystèmes, de concurrencer ou de menacer les espèces locales. L'environnement à proximité des aires protégées est susceptible de servir de tremplin à ces espèces introduites avant qu’elles ne pénètrent dans les aires protégées. Cependant, on sait peu de choses sur le rôle que jouent les zones entourant les aires protégées dans cette dynamique de colonisation. Dans cette thèse, nous nous sommes concentrés sur les zones entourant les aires protégées pour aborder la question de la perméabilité des aires protégées aux espèces non indigènes. En étudiant les aires protégées en Norvège, nous avons montré que le pool d’espèces non indigènes présent autour des aires protégées a un impact qualitatif sur la communauté d'espèces non indigènes présentes dans les aires protégées, les espèces non indigènes envahissantes étant présentes dans une plus grande proportion dans les aires protégées (40 %) que dans leurs ceintures (12 %). Le nombre d'espèces non indigènes présentes autour des aires protégées détermine également le nombre d'espèces non indigènes présentes dans les aires protégées. Nous avons aussi mis en évidence la dynamique de la colonisation de l’extérieur vers l’intérieur des aires protégées en montrant que les espèces non indigènes étaient détectées dans les aires protégées plusieurs années après avoir été détectées autour d’elles. En outre, nous avons montré dans quatre pays européens que le type d’occupation du sol à proximité et au sein des aires protégées joue un rôle central dans l'établissement des espèces non indigènes dans les aires protégées. Ainsi, les habitats fortement anthropisés autour des aires protégées favorisent la présence d'espèces non indigènes dans les aires protégées, quel que soit le type d’occupation du sol dans ces dernières. Enfin, nous avons étudié la dynamique de colonisation d'Acacia dealbata, une espèce d'arbre non indigène envahissante au centre du Portugal, autour et dans cinq aires protégées, au cours de ces vingt dernières années. Nous avons montré que les perturbations par les incendies et la perte de couverture forestière favorisaient la présence de l'espèce. Cette thèse a mis en évidence l'importance des zones autour des aires protégées dans la colonisation de celles-ci par les espèces non indigènes. Ces résultats sont particulièrement pertinents pour les futures stratégies de gestion des espèces non indigènes dans les aires protégées
Protected areas are among the key elements of global biodiversity conservation strategies and aim to conserve native species, habitats and ecosystems. Globalisation has led to increased introductions of species outside their natural range. In their new environment, some of these non-native species have the potential to affect ecosystems and compete with or threaten native species. The environment in close proximity to protected areas is likely to be the stepping stone for non-native species to become established in protected areas. However, little is known about the role that protected area surroundings play in the permeability of protected areas to non-native species. In this thesis, I focused on protected areas and their surrounding belts to address the issue of permeability to non-native species. Examining protected areas in Norway, I showed that non-native species surrounding protected areas have a qualitative impact on the community of non-native species in protected areas. Moreover, the proportion of invasive species was higher in protected areas (40 %) compared to their belts (12 %). The number of non-native species in the surrounding areas also significantly determined the number of non-native species in protected areas. I have also highlighted the dynamics of colonization from the belts to the protected areas by showing that non-native species were detected in the protected areas on average several years after they were recorded in the belts. In addition, I showed in four European countries that the type of land use and land cover in the proximity and within protected areas plays a central role in the establishment of non-native species in protected areas. Anthropogenic land use and land cover around protected areas promoted the establishment of non-native species inside protected areas, regardless of the land use and land cover present in them. Finally, I investigated the colonization dynamics of Acacia dealbata, an invasive t ree species, in and around protected areas in central Portugal over the last twenty years. I showed that disturbances by fires and the loss of tree cover had a significant positive effect on the presence of the species. This thesis highlights the importance of the protected area surroundings for the colonization of non-native species. This is particularly relevant for future management strategies for non-native species in protected areas

Humankind has redistributed a large number of species outside their native geographic ranges. Although the majority of introduction attempts fail to establish populations, the cumulative negative effect of successful non-native species has been and will continue to be large. Historical records of land bird introductions provide one of the richest sources of data for testing hypotheses regarding the factors that affect the successful establishment of non-native populations. However, despite comprehensive summaries of global avian introductions dating back two decades only very recent studies have examined the successful establishment of non-native bird species worldwide. It is clear that a non-random pattern exists in the types of land bird species that have been chosen by humans to be introduced outside their native range. Out of the 44 avian families from which species have been chosen for introduction almost 70% of introduction attempts have been from just five families (Phasianidae, Passeridae, Fringillidae, Columbidae, Psittacidae). Notably, these families include game species, insectivorous song birds, and species from the pet trade. It has been hypothesised that the fate of introduced species may be determined in part by heritable characteristics that are shared by closely related taxa. In my analyses, I have used current comparative methods to demonstrate that intrinsic eco-physiological characteristics are significant predictors of the worldwide success of introduced land bird species. The results of my analyses contribute to a greater ecological understanding of the traits that correlate with the successful establishment of non-native species. Notably, the three major conclusions that I have drawn from this thesis are: 1. Non-random patterns of successful establishment exist for introduced land bird taxa that have experienced a repeated number of introduction attempts. This result supports the idea that introduced species have an inherent likelihood of either succeeding or failing to establish non-native populations. 2. Eco-physiological traits are important correlates for determining the variability in introduction outcome for non-native land bird species. With reliable information on introduction attempts and taxa-specific traits predictive models are possible that quantify the outcome of repeated introduction attempts across non-native species. 3. Islands are not universally less resistant than mainland regions to the successful establishment of non-native species. This perception is a reflection of the greater number of introduction attempts to islands rather than an effect of biotic resistance. Any differences in the success of introduction attempts can be attributed largely to differences in the proportion of introductions that have been made across biogeographic regions. I have highlighted that data are accessible for global analyses of the variability in the successful establishment of non-native species. Although establishment success is not a deterministic process, the characteristics of an introduced species can influence the probability of its succeeding. I have shown that with adequate eco-physiological information, and for introduced land bird species at least, this probability can be predicted. These results refute previous suggestions that the stochastic component of species introductions will always overshadow any emerging patterns of successful establishment among non-native populations.

Arid and semi-arid ecosystems of the southwestern U.S. are experiencing major changes that have profound impacts for community structure and ecosystem function. First, these ecosystems are experiencing dramatic shifts in vegetation composition as a result of the invasion of non-native species. Second these ecosystems are predicted to undergo substantial shifts in climate regime, which include increases in the variability and frequency of extreme temperature and precipitation events. It is not well understood how these current and predicted changes will affect the physiological performance of different plant types in arid and semi-arid ecosystems. To address the effect of these changes, this dissertation focused on the photosynthetic response of a native and non-native grass species, and dominant shrub species to precipitation across contrasting soil surfaces in southeastern Arizona. The native and non-native grasses were exposed to wet and dry seasonal precipitation and responses to precipitation events ('pulses') were measured over the course of a summer growing season. To gain a mechanistic understanding of these patterns, the biochemical and diffusion limitations to photosynthetic function were measured over the course of a pulse period. Building on this foundation, natural stands of the non-native grass species were exposed to sequences of different sized pulse events. The physiological performance of a dominant shrub species, Larrea tridentata, was measured in order to determine the biochemical and diffusional constraints to photosynthetic function across seasons and contrasting soil surfaces. The results showed that leaf area development of these grass species affects water availability and time lags in photosynthetic response. Initial soil moisture conditions across contrasting soil surfaces influence the magnitude of photosynthetic response in grasses. Large photosynthetic responses of the non-native grass require large and consecutive precipitation pulses. Co-limitation of photosynthesis of Larrea tridentata by diffusion and biochemistry does not illustrate typical trends across seasons and soil surfaces. Overall results demonstrate the importance of determining the mechanisms responsible for observed leaf-level photosynthetic patterns across individual pulse events, seasons, and contrasting soil surfaces. This is especially important for predicting the magnitude of the response of plant communities in arid and semi-arid ecosystems to species invasions and changes in climate.

Humankind has redistributed a large number of species outside their native geographic ranges. Although the majority of introduction attempts fail to establish populations, the cumulative negative effect of successful non-native species has been and will continue to be large. Historical records of land bird introductions provide one of the richest sources of data for testing hypotheses regarding the factors that affect the successful establishment of non-native populations. However, despite comprehensive summaries of global avian introductions dating back two decades only very recent studies have examined the successful establishment of non-native bird species worldwide. It is clear that a non-random pattern exists in the types of land bird species that have been chosen by humans to be introduced outside their native range. Out of the 44 avian families from which species have been chosen for introduction almost 70% of introduction attempts have been from just five families (Phasianidae, Passeridae, Fringillidae, Columbidae, Psittacidae). Notably, these families include game species, insectivorous song birds, and species from the pet trade. It has been hypothesised that the fate of introduced species may be determined in part by heritable characteristics that are shared by closely related taxa. In my analyses, I have used current comparative methods to demonstrate that intrinsic eco-physiological characteristics are significant predictors of the worldwide success of introduced land bird species. The results of my analyses contribute to a greater ecological understanding of the traits that correlate with the successful establishment of non-native species. Notably, the three major conclusions that I have drawn from this thesis are: 1. Non-random patterns of successful establishment exist for introduced land bird taxa that have experienced a repeated number of introduction attempts. This result supports the idea that introduced species have an inherent likelihood of either succeeding or failing to establish non-native populations. 2. Eco-physiological traits are important correlates for determining the variability in introduction outcome for non-native land bird species. With reliable information on introduction attempts and taxa-specific traits predictive models are possible that quantify the outcome of repeated introduction attempts across non-native species. 3. Islands are not universally less resistant than mainland regions to the successful establishment of non-native species. This perception is a reflection of the greater number of introduction attempts to islands rather than an effect of biotic resistance. Any differences in the success of introduction attempts can be attributed largely to differences in the proportion of introductions that have been made across biogeographic regions. I have highlighted that data are accessible for global analyses of the variability in the successful establishment of non-native species. Although establishment success is not a deterministic process, the characteristics of an introduced species can influence the probability of its succeeding. I have shown that with adequate eco-physiological information, and for introduced land bird species at least, this probability can be predicted. These results refute previous suggestions that the stochastic component of species introductions will always overshadow any emerging patterns of successful establishment among non-native populations.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Science, Environment, Engineering and Technology
Full Text

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.

Thesis (Honors)--Ohio State University, 2006.
Title from first page of PDF file. Document formatted into pages: contains 21 p.; also includes graphics. Includes bibliographical references (p. 12-13). Available online via Ohio State University's Knowledge Bank.

Coastal Sage Scrub (CSS) is a low scrubland plant community native to the coasts of California, housing many threatened and endangered species. Due to the invasion of non-native plants, many areas of CSS have type converted to annual grasslands and the fire frequency has accelerated; fire in turn, may facilitate further invasion, leading to a loss of biodiversity. While many studies document post-fire succession in these communities, pre-fire data are rarely available for comparison, especially data on seedling emergence. I analyzed post-fire recovery of a type-converted grassland community, comparing seedling emergence data for the first and third year after fire to the three years preceding the fire. Non-native species abundances declined more after the fire than did native abundances. This pattern was still present in 2015, three years post-fire. Two native species, Amsinckia menziesii var. intermedia (Amsinckia) and Phacelia distans (Phacelia), were subjects of seed addition treatments pre-fire, but I found no evidence that past seeding increased their abundances post-fire. Amsincki did recover to its pre-fire density three years after the fire, while the density of Phacelia declined over 75% in both the year immediately post-fire and three years after the fire. However, a third native species, Lupinus bicolor (Lupinus), was both much more abundant and also more spatially widespread both immediately after the fire and two years later. This supports the hypothesis that Lupinus is stored in the soil seed bank and the fire may have given this species the opportunity to recover by lowering abundances of non-native competitors. This analysis will inform future conservation efforts by improving our understanding of how seed banks impact the post-fire recovery of native species.

Invasive non-native species place high pressures on native communities and can result in ecological impacts often associated with differences in key functional behaviours that mediate top-down and bottom-up forces. In this thesis, I use two model systems, the UK Coccinellidae system and the UK freshwater amphipod system, to quantify per-capita differences between native and invasive non-native species. I scale these studies up to more complex ecological communities and attempt to account for additional environmental pressures (e.g. pathogenic infection). First, I present a laboratory experiment to quantify the per-capita differences in predatory behaviour between native and invasive non-native Coccinellidae with a pathogen (Beauveria bassiana) exposure treatment. H. axyridis was the most effcient predator and pathogenic infection reduced the forage ability in all species. Second, I used existing H. axyridis distribution and aphid abundance data to quantify H. axyridis' impact through top-down forces. The arrival of H. axyridis is correlated with significant changes in aphid abundance and, of the 14 species studied, five declined in abundance, four increased, while the remaining five showed no significant change. Third, I measured the per-capita differences in detrital processing rates between native and invasive freshwater amphipods when provided with three diets of differing resource quality and maintained at three temperatures. The rates of detrital processing varied between the native and invasive non-native species and between the temperature and resource quality treatments. Fourth, I applied native and invasive amphipods at two density treatments (high and low) to a field mesocosm experiment to measure how the per-capita differences impacted more complex ecological systems. The presence of invasive amphipods changed the macroinvertebrate community composition and ecosystem functioning. I finish by highlighting that our understanding as to how the pressures of invasive non-native species interact with additional environmental stressors remains limited and an area that warrants further investigation.

This thesis focuses on interactions between two invasive species, the western mosquitofish (Gambusia affinis) and the red swamp crayfish (Procambarus clarkii), and two desert fishes, the Amargosa pupfish (Cyprinodon nevadensis) and the endangered Pahrump poolfish (Empetrichthys latos latos). Chapter one is a literature review on the impacts of invasive species on various desert fishes. Chapter Two reports the results of multiple mesocosm experiments that show poolfish are unlikely to persist in the presence of mosquitofish. Chapter Three reports the results of a mesocosm experiment that tested the combined impacts of crayfish and mosquitofish on poolfish populations. Chapter Three mimics a historic case study in Nevada, where the Lake Harriett poolfish population crashed following the introduction of crayfish and mosquitofish. Chapter Four reports results of a mesocosm experiment that revealed density dependent effects of invasive crayfish on pupfish populations, with pupfish populations negatively affected when crayfish were at high densities.
Nevada State Wildlife Grant
North Dakota State University. Environmental and Conservation Science Program
Desert Fish Council

Novel ecosystems emerge from alterations to historic abiotic regimes and contain new species combinations. Everglades canals offer an opportunity to understand the function of novel habitat for native and non-native fishes and how novel conditions in turn influence distribution, abundance and assembly patterns. I examined native and non-native fish assemblages collected across a gradient in novelty, defined by the loss of wetland connectivity and habitat complexity. As novelty increased, native species richness and abundance strongly declined, and the contribution of non-natives increased. Community structure vastly differed among canals and was strongly influenced by spatial factors and secondarily by hydrological factors. Natives and non-natives had opposing responses to key hydrologic and habitat parameters. This study represents the first comprehensive assessment of Everglades canal fishes, providing insight into the factors influencing native and non-native abundance and assembly patterns and contributing to our understanding of this novel but permanent habitat.

The increase of human population and their pressures in coastal areas is causing an exponential sprawl of artificial structures in marine areas, leading to the loss of natural habitats. Artificial structures are characterised by low species richness and a prevalence of non-native species compared to natural rocky reefs. Commercial and tourist ports are examples of artificial habitats. Little is known about the distribution and dynamic of the species inhabiting ports, and the factors leading to a prevalence of non-native species in these habitats are still not fully understood. Here, the distribution and abundances of two native (Mytilus galloprovincialis, Ostrea edulis) and two non-native (Xenostrobus securis, Crassostrea gigas) bivalve species that grow on the artificial seawalls of the canal-port of Ravenna were assessed to: 1) explore their distribution in different areas of the harbour, and 2) identify whether the observed patterns were related to variations in environmental parameters or to variable supply of larvae reaching different areas of the port and settling on the artificial seawalls. DNA extraction and amplification protocols were developed to barcode the bivalves settlers due to the impossibility to identify them microscopically. Results showed an increase of non-native species as the canal-port goes inland. Temperature, oxygen and nitrate seawater concentration explained most of the variation in species abundance among sites. The non-native mussel X. securis was associated to higher sea surface temperatures compared to the native M. galloprovincialis. Settler abundances were clearly correlated to the spawning window of the species, but not to adult abundances on the seawalls, suggesting a prevailing role of post-settlement processes. Future work should explore the potential role of other environmental variables, extend the duration of the observations, and use a metagenomics approach to characterise propagule pressure dynamics in the water column.

Includes bibliographical references.
Freshwater fishes are among the most threatened taxa in the world. Increasing demand for freshwater, habitat degradation and the introduction of non-native species, will continue to place pressure on the remaining native freshwater fishes. A meta-analysis estimated that more than 90% of river habitat in three major catchments has been invaded by non-native fish and that catchments covering less than 1% of Cape Floristic Region have no recorded non-native fish introductions, the major rivers containing 10 or more non-native species. The majority of the native fishes continue to be threatened by the presence of non-native fish.

Boston University. University Professors Program Senior theses.
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2031-01-02

Lethal biotic interactions strongly influence the potential for aquatic non-native species to establish and endure in habitats to which they are introduced. Predators in the recipient area, including native and previously established non-native predators, can prevent establishment, limit habitat use, and reduce abundance of non-native species. Management efforts by humans using methods designed to cause mass mortality (e.g., trapping, biocide applications) can reduce or eradicate non-native populations. However, the impacts of predator and human induced mortality may be mitigated by the behavior or population-level responses of a given non-native species. My dissertation examined the responses of non-native aquatic species to the risk of predation by novel (i.e., no previous exposure) predators in the recipient community and indicators of potential compensatory responses by non-native populations to increased mortality resulting from removal efforts. My dissertation addresses four primary questions. 1) Can first generation, naïve invaders recognize and defend against predators found within the region of invasion through the expression of inducible defenses? 2) Can the overcompensatory potential of a population be predicted through examinations of intraspecific interactions of individuals from the population? 3) What is the relationship between removal effort outcome (i.e., successful or unsuccessful reduction of the target population) and compensatory population responses? 4) Is there a relationship between characteristics of removal efforts that are typically available to managers (e.g., target area size, target area connectivity, removal methodology) and compensatory population responses that could indicate the relative likelihood of compensation resulting from removal efforts? An invading species should be more likely to establish if it can successfully identify and defend against predators in the recipient range, such as through the expression of inducible defenses. Inducible defenses are behavioral or physiological changes that reduce an organism's susceptibility to predation. Through a series of laboratory experiments, I tested whether inducible defenses, in the form of increased burrowing depth, may have benefited the early stage of invasion of Nuttallia obscurata (purple varnish clam), an established Northeast Pacific invader. Specimens of N. obscurata were collected from introduced populations in the Northeast Pacific and from a native population in Japan. The clams were exposed to chemical and physical cues from Northeast Pacific crab predators, including the native Metacarcinus magister (Dungeness crab), an abundant and frequent predator of N. obscurata. While introduced N. obscurata increased their burrowing depth in the physical presence of M. magister, clams collected from their native range showed no such response. This lack of increased burrowing depth by naïve clams in response to a predator native to the newly invaded range, but a significant increase in depth for clams from populations established in the range suggests that while inducible defenses likely did not contribute to the initial establishment of N. obscurata in the Northeast Pacific, they may contribute to their continued persistence and expansion in their introduced range. Some efforts to reduce invasive populations have paradoxically led to population increases. This phenomenon, referred to as overcompensation, occurs when strong negative density-dependent interactions are reduced through increased mortality within a population, resulting in an increase in the population's recruitment rate sufficient to increase the population's overall abundance. Increases in a population's recruitment rate can result from reduced cannibalism of juveniles resulting in lower mortality of new recruits, from increased adult reproductive output, which increases the number of potential recruits, or from reductions in size and/or age at maturity of the unharvested population, which increases the number of reproductive individuals. I predicted the overcompensatory potential of a population of Carcinus maenas (European green crab) in Bodega Harbor, California, using a series of laboratory and field experiments examining intraspecific pressures of adults on juveniles in the population. This measure of intraspecific pressure was used to predict the overcompensatory potential of the population in response to increased mortality from ongoing removal efforts. This prediction was then assessed using pre- and post-removal surveys of juvenile recruitment in Bodega Harbor compared to nearby populations, testing for evidence of overcompensation. While adult C. maenas in Bodega Harbor had limited negative impacts on juveniles, I concluded it was unlikely to result in overcompensation. Relative juvenile abundance did not statistically increase in removal compared to reference populations, consistent with my conclusion from the experiments. Increases in recruitment rates can occur as a result of efforts to remove non-native species. This increase in recruitment can result in overcompensation, but more commonly results in compensation, where recruitment rates increase relative to pre-removal recruitment but does not result in in the population's abundance exceeding pre-removal levels. However, a detailed and accurate prediction of the response of a population to harvest is time consuming and data intensive. This is not feasible for most efforts to eradicate non-native species, which have the greatest chance of success when enacted rapidly after detection. For my final chapter, I performed a literature review and accompanying statistical analysis to determine if typically available information related to the removal effort (site size, site connectivity, and removal technique) could be used to determine increased risk of compensation for a given effort to remove aquatic invasive species. Compensation was closely linked to unsuccessful removal efforts and was observed only among efforts utilizing physical removal methods. However, the frequency with which compensation occurred varied with the exact technique employed, occurring most frequently in removal utilizing electrofishing. Additionally, evidence of compensation was more frequent among larger removal areas with variable connectivity. While other predictors (temperature, effort, etc) might add to the predicative power, the findings of the review provide criteria for managers to determine the relative risk of compensation prior to the start of removal. Further understanding of how invasive species respond to lethal biotic interactions, including anthropogenically mediated control measures, can aid in assessing the risk of invasion for a given species and inform managers of the risk of complications resulting from removal efforts. While inducible defenses may contribute to the long-term success of an introduced species in their recipient range, my findings did not support the idea that inducible defenses triggered by predator cues contributed to their initial introduction in this case. However, research on other non-native species and offspring of previously naïve prey would allow for a clearer picture of the role of inducible defenses in the invasion process. Compensation resulting from removal efforts does not guarantee failure, and certain characteristics of removal efforts seem to indicate increased risk of compensation. Together these components help identify how biotic interactions surrounding mortality risk of an invading species help shape the trajectory of invasion.

The purpose of this study was to determine if the complexity and surface area of a macrophyte’s structure has an influence on invertebrate colonization, and to determine the influence of two non-native species on invertebrate colonization. Three plant architectures were compared. Floating leaved plants were represented by the following species: Nuphar lutea, Nymphaea odorata, and Brasenia schreberi. Moderately dissected leaved plants were represented by Potamogeton natans, and highly dissected leaved plants were represented by two non-native species, Myriophyllum spicatum and Myriophyllum heterophyllum. The number of invertebrates/g dry biomass and the number of individuals/m², diversity, evenness, and richness were calculated for comparison. The density of invertebrates was significantly different among the different plant architecture types for both individuals per m² and individuals per/g dry biomass (ANOVA, F=33.53, p < 0.0001; ANOVA, F=194.41, p < 0.0001). The highly dissected milfoils had the greatest density of individuals per gram dry plant biomass compared to the moderately dissected plants, and the moderately dissected plants had a greater density of individuals per gram dry mass than floating leaved plant. There were also differences in terms of invertebrate community diversity (H'), (ANOVA, F=l7.08, p < 0.001), and richness (ANOVA, F= 35.52, p < 0.001), but not evenness (ANOVA, F = 1.83, p = .0961). When the number of invertebrates/g dry plant biomass was examined in lakes where the highly dissected plants were ”rare/not observed", there was a lower density of invertebrates per gram dry biomass. This was significantly lower than in lakes where the highly dissected plants were both ”common” and ”dominant” (ANOVA, F=3.31, p = 0.0393). Data analysis was strongly affected by the density of the oligochaete Sty/aria and the amphipod Hyallela azteca, as evident in the Principle Component Analysis. Parameters associated with the two axes, principle component 1 and principle component 2, explained 86% of the variation in epiphytic invertebrate density.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O presente estudo foi conduzido em quatro lagoas marginais da porção superior do reservatório de Rosana, bem como no canal principal do rio Paranapanema. O objetivo do primeiro capítulo foi analisar a composição e os atributos ecológicos das assembléias fitoplanctônicas, recurso trófico primário das cadeias alimentares aquáticas. O segundo capítulo trata da comunidade zooplanctônica (Cladocera e Copepoda) e sua distribuição nos ambientes analisados. O terceiro trabalho procura avaliar se a introdução de uma espécie exótica de peixe (Cichla kelberi) pode causar alterações na estrutura da ictiofauna local, com uma possível redução da sua diversidade. Por fim, o quarto capítulo refere-se à alimentação da ictiofauna de pequeno porte, através da análise da dieta e do hábito alimentar das espécies, considerando principalmente a importância da comunidade planctônica para essa fauna. O número total de táxons de fitoplâncton identificados foi de 283. Zygnemaphyta foi o grupo com maior número de espécies, seguido por Chlorophyta e Bacillariophyta. Maior riqueza, abundância e biomassa de fitoplâncton foram observadas nas lagoas, especialmente durante o período chuvoso. O número total de táxons de zooplâncton identificados foi de 72. As lagoas laterais e o período chuvoso apresentaram maior abundância de organismos. Calanoida foi o grupo dominante nas assembléias zooplanctônicas. Os resultados mostraram que no sistema de lagoas laterais as comunidades são controladas por mecanismos ascendentes (“bottom-up”). Um total de 4693 peixes, pertencentes a 43 espécies foram amostrados. A Ordem Characiformes foi a mais abundante, seguida por Perciformes e Siluriformes. Não houve diferenças estatísticas na riqueza, na abundância, na biomassa, na média do comprimento, na composição das assembléias e na diversidade de peixes, comparando-se o período...
The study was carried out in four lateral lagoons of the tail region of Rosana reservoir, as well as in the river/reservoir main channel. The aim of the first chapter of the thesis was to analyze the composition and ecological attributes of the phytoplankton assemblages, primordial trophic resource of the aquatic food chains. The second chapter is focused on the zooplankton community (Cladocera and Copepoda) and their distribution in the study environments. The third chapter tries to assess whether the introduction of a non native fish species (Cichla kelberi) may promote alterations in the local ichthyofauna, with a possible reduction in its diversity. Finally, the last chapter discusses the ichthyofauna feeding, through the analysis of diet and feeding behavior of fish, considering mainly the importance of plankton organisms as a resource. The total number of phytoplankton taxa identified was of 283. Zygnemaphyta was the most specious group, followed by Chlorophyta and Bacillariophyta. Higher richness, abundance and biomass were observed in the lagoons, especially during the rainy period. The total number of zooplankton taxa was 72. Higher zooplankton abundance was observed in the lateral lagoons and in the rainy period. Calanoids were the dominant group in the zooplankton assemblages. The results indicated that in the lateral lagoons system, the communities are controlled by bottom-up mechanisms. A total of 4,693 fish, belonging to 43 species was sampled between 2004 and 2009. The order Characiformes was the most abundant, followed by Perciformes and Siluriformes. There were no differences in composition, richness, abundance, biomass, mean length and diversity, when compared the periods previous and after the introduction of Cichla. The results showed that the feeding of the river fish assemblages was different from the lagoons... (Complete abstract click electronic access below)

Anthropogenic climate change is one of the main challenges affecting the globe, with particular implications for the oceans. Marine climate change research has moved forward rapidly in recent years, and a range of physical model outputs are available that can be used by ecologists to help predict how species might be affected into the future. Policy makers require a level of understanding of how certain species and their ranges might change so that they can respond with sustainable management actions. This thesis aims to make use of a number of modelling techniques to explore implications of past and future conditions for marine species, and to appraise those tools that can be used under differing circumstances. Policy questions are answered relating to changes in the abundance and distribution of marine species. The links between historical climatic conditions and Barents Sea cod abundance are explored using Generalised Additive Models using data collected in the middle of the 20th century. This valuable historical data indicated that cod have temperature preferences and expand and shift their distributions based on environmental conditions. A simpler modelling technique is used to examine how oxygen conditions have changed in recent decades in the North Sea, how they might change in the future, and what implications this has for commercial fish species. The models show that oxygen conditions have improved recently and that they will not decrease to levels that result in large negative effects in the coming century. Species distribution modelling using a combination of global and downscaled model outputs shows that the UK will become more suitable for some non-native and harmful algal species in the 21st century, and less suitable for others. The model outputs contribute to the understanding of climate change effects and development of management tools to ensure the resilience of marine ecosystems into the future.

Invasive plant species are perceived as a problem globally, but management occurs locally. Theoretical developments concerning the distribution of plant species and invasions have generally focused on coarse scales, with relatively little work performed at finer scales relevant to local landscape management. The majority of such model predictions are static reflections of current conditions. As species invasions are a temporally variable process, the need for tools to predict invasions through both space and time are vital. Thus, this thesis explored distribution models to predict non-native species occurrence, investigated sources of uncertainty in these models, and quantified the key drivers of non-native species metapopulation dynamics. Sampling methodology and sample size requirements to inform logistic regression models used to predict invasive species realized distributions were evaluated with simulation and empirical data from two multi-species surveys. Transect sampling was the most efficient way to generate species occurrence data and consequently landscape scale species distribution models. Empirical and simulation modeling results indicated minimum sample sizes of between 0.06 and 0.23% of the study area to maximize model predictive ability, independent of site characteristics. However, landscape scale species distribution models were more predictive at sites with steeper environmental gradients and for species at their ecophysiological range limits. Detection error in the plant species surveys was also quantified, as well as its effects on predictions and uncertainty of species distributions. Detection error did not practically alter predictions, nor model based uncertainty estimates if the detection rate was greater than 87%. However, at lower detection rates care needs to be taken when interpreting response variables and prediction certainty. Finally, multi-season repeat survey data were used to investigate the key spatial and temporal drivers of non-native species colonization and extinction. The drivers of non-native species colonization and extinction were sometimes simple but other times resulted from complex interactions between dispersal, disturbance, habitat and temporal climatic variation. Overall, these results demonstrate the need for reliable species occurrence records and monitoring data to fully characterize species distributions at present and their dynamics resulting in future distributions. 'Co-authored by Bruce D. Maxwell, Megan D. Higgs, Lisa J. Rew and Subhash R. Lele.'

Natural and anthropogenic disturbances have influenced forest stand structure and affected species compositions within forests for millennia. Disturbances such as fire, severe weather events, and forest management practices may result in significantly reduced tree biomass. Thus, these disturbances may lower canopy closure and stem density in support of forest management goals, such as open oak woodland restoration, or promote an increase in species richness within the forest understory. However, these types of disturbance may also produce the unwanted consequence of opening pathways for the invasion of non-native species. Once established, these non-native species may threaten native plant communities and biodiversity. Here, we elucidate how varied natural and anthropogenic disturbances have altered forest stand structure. One consequence of disturbance has been the increase in the presence and cover of non-native species within upland oak forest sites located in the Daniel Boone National Forest, Kentucky. The results of these studies suggest that timely and effective management strategies are needed to minimize non-native species impact on forested habitats following disturbance, and to promote the desired structural shifts that will sustain diverse habitats and support biodiversity.

Fire is a natural component of, and serves as a tool for, the restoration of forested ecosystems worldwide; however, disturbance due to fire also has been implicated in the proliferation of invasive species. How these fires affect occupancy and use of the forest by wildlife is of great concern, in particular, the differential response of non-native and native species. In the North American Southwest, prior to European settlement, frequent wildfires helped to maintain forest structure. We examined the effect of a large wildfire on an introduced population of the Abert's squirrel (Sciurus aberti) that has invaded the high elevation forests inhabited by the critically endangered Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis). We found that introduced Abert's squirrels were more common than native red squirrels in burned areas. Abert's squirrels did not abandon burned areas but nested, foraged, and did not adjust their home range size in burned areas. This suggests that invasive Abert's squirrels are better able to exploit burned areas than native red squirrels and that fire can favor non-native species. This interaction between non-native species, native species, and fire adds new insight into the complexities of conservation and restoration of ecosystems and helps to inform conservation activities worldwide.

Since their recent introductions into Florida waters, three nonnative species [Perna viridis Linnaeus, 1758 (Asian green mussel), Mytella charruana d'Orbigny, 1846 (charru mussel) and Megabalanus coccopoma Darwin, 1854 (pink titan acorn barnacle)] have expanded both north and south along the Atlantic coast. Very little research has been done to understand how these nonnative species interact with the native eastern oyster (Crassostrea virginica Gmelin, 1791), which is a keystone species that provides important ecological services and economic benefits. To test the potential effects of P. viridis, M. charruana and M. coccopoma on C. virginica, I addressed the following questions: 1a) Does the presence of nonnative species decrease oyster larval settlement? 1b) Do oyster larvae avoid settling on oyster shells to which nonnative species are attached? 2a) Do nonnative species decrease survival of juvenile oysters (spat)? and 2b) Do nonnative species hinder spat growth? My manipulative experiments showed that the tested nonnative species influenced settlement, growth and survival of C. virginica in unique ways. Megabalanus coccopoma decreased the total number of settled oyster larvae, but did not influence larval preference or survival and growth of spat. Perna viridis negatively influenced larval settlement and oyster larvae avoided settling on shells of P. viridis. Mytella charruana had no influence on the total number of settled larvae but oyster larvae avoided settling on oyster shell with M. charruana or on the mussel shells themselves. Furthermore, both nonnative mussels negatively affected the survival of juvenile oysters, but only M. charruana reduced spat growth. These three nonnative species should be classified as invasive species because all had negative effects on the native oyster C. virginica.
M.S.
Masters
Biology
Sciences
Biology

Habitat destruction/alteration and non-native species are widely considered the two most serious threats to biodiversity within freshwater ecosystems, which are among the most threatened in the world. I examined the effects of these factors, specifically focusing on land use and non-native species as drivers of abundance patterns of native fishes in the highly invaded and anthropogenically impacted New River basin (NRB) in the Appalachian region of the United States. In chapter 2, I examine current native and non-native species abundance patterns related to the highly variable land-use mosaic present across the NRB, with specific focus on the species-specific effects of intensive land-use practices (agriculture and urbanization) at varying spatial extents (upstream watershed, upstream riparian, and local riparian). In chapter 3, I investigate historical context of basin-wide and site-level abundance spread and decline of natives and non-natives in the upper and middle New River basin (UMNR) over the past 60+ years. Finally, in chapter 4, I partition the variation in native species abundance explained separately by land use and non-native species to determine which factor might be most influential in describing abundance distributions of UMNR native fishes over the past 20+ years. My results indicate widely varying responses of native species to various combinations of intensive land use and non-native species across contributing watersheds and widespread biotic homogenization and native species declines over the past 60+ years. These declines include reductions in unique communities and endemic species provided little consideration or protection under current conservation law. I suggest potential avenues for improvement of conservation actions to help preserve these unique species and communities based on their responses to various land-use and non-native species stressors. My study framework should be broadly applicable to other drainages and should provide opportunities for early identification of potential native species declines and the stressors that may be contributing to them.
Master of Science
Freshwater fishes are experiencing world-wide declines that have the potential to cause major negative ecological and economic impacts. Two of the biggest contributors to fish declines are habitat destruction and non-native species introductions. I examined populations of numerous fish species in the New River basin (NRB) in the Appalachian region of the United States to identify declining native species and determine how intensive land use (one type of habitat destruction) and non-native species may be contributing to these trends. My results suggest that nearly half of the native species occurring in the NRB may be experiencing widespread reductions in abundance. As a result of these declines and the spread of a few common native and non-native species, fish communities across the NRB are becoming less unique over time. Land-use changes, such as agricultural and road development near streams, which contribute to increased soil erosion and run-off of silt and sand into streams, could be causing broad habitat changes that lead to diminished populations of sensitive species and overall local and regional fish diversity. While no single non-native species may be held responsible for all native fish species declines in the NRB, complex interactions, such as competition and predation, between many natives and non-natives altogether could be contributing to many native fish declines. Farmers and other landowners can help to prevent future fish declines by re-establishing natural vegetation, such as trees, along streambanks and implementing other practices, such as cattle fencing, that reduce the streambank and soil erosion that harms fish habitat. Other stakeholders, such as anglers, can help prevent future native fish declines by limiting introductions of additional non-native species. For example, these stakeholders could avoid releasing aquatic pets and live bait into NRB streams. These practices would help limit future negative impacts caused by non-native species.

Alongside the destruction of habitat, the impact of invasive alien species (IAS) is considered as one of the most important threats to global biodiversity. Therefore, international directives as well as national legislation call for measures to prevent the further spread of already established IAS as well as to limit their negative effects on native flora and fauna. This study deals with one of these non-native species – the American mink (Neovison vison). In order to get information about ecology and behaviour of this semiaquatic carnivore, a small population in a north German fishpond area, where mink has been spreading since the 1970s, was investigated. During the years 2003 to 2006 data about annual and circadian activity patterns, space use, territorial system as well as feeding habits and their variations during different seasons were collected. For this purpose, altogether 14 individuals (nine males, five females) were monitored using radio-telemetry. Based on the results, the potential impact of American mink on indigenous species was discussed and implications for mink control and management were deduced. American mink are difficult to radio tag. The small difference between their head and neck circumferences mean that the radio collars must be worn tightly to prevent loss. A methodological evaluation of conventional collar transmitters revealed that in six out of eight cases serious skin injuries on the necks were the consequences. Therefore, all radio collars were removed and radio transmitters were surgically implanted in the peritoneal cavity of mink by veterinarians. One male bit open the sutures and died after emergency surgery, but in 13 cases implantation did not affect survival or reproduction of the mink. With reference to animal welfare, intraperitoneal implantation of radio transmitters (in combination with observation and quarantine for several days after operation) instead of external radio collars were recommended for long term telemetry studies of American mink. Analyses of annual activity patterns revealed significant differences in seasonal activity rates. Both sexes reduced their average activity rates in cold winter months (October to February) to about 23 %. This energy-saving strategy is possible because of sufficient food availability, especially of fish, at this time. In March, male as well as female mink considerably increased their activity to almost 40 % due to the mating season. In summer months, during the pup-raising period (May to August), female activity continued to be high (between 40 and 50 %). However, male mink which are not involved in rearing the young, were less active (about 30 %) until July. But in August and September, the time of juvenile dispersal followed by changes in the territorial system and intraspecific aggression, activity rates of males increased again up to 43 %. Circadian activity rhythms differed markedly between sexes. All investigated females exhibited a perennial diurnal pattern. Three of five investigated male mink showed typical nocturnal activity throughout the year. Two males displayed arrhythmic behaviour; they did not prefer any time of the day for activity. On the one hand, gender differences in annual as well as circadian activity patterns of American mink reflect the diversity in ecological constraints, primarily the investment into reproduction. On the other hand, the different temporal strategies of sexes may have the potential to reduce intraspecific, especially intersexual competition. Investigating territorial systems and space use of mink, in comparison to other European studies, relatively large home ranges combined with a quite low population density were observed. In summer months male mink used on average 15.4 km length of waterway and female mink used on average 9.3 km length of waterway. In accordance with the trend of activity rates, male and female mink reduced their large summer home ranges by more than half during the cold winter period. But all-season male mink used significantly larger areas than female mink. High intersexual overlapping rates of home ranges and low levels of intrasexual overlapping of neighbouring home ranges confirm intrasexual territoriality of American mink. Probably, the low population density (0.6-0.7 individuals/km2) allows such high variations in seasonal and sexual home range size. During the mating season males considerably enlarged their home ranges and roamed nearly through the entire study area in search of receptive females. The shifting of stable temporary home ranges observed within one season or between the same seasons of consecutive years demonstrates the highly dynamic nature of spatial behaviour among American mink. The recorded characteristic features of spatial and temporal behaviour should be considered when planning monitoring- and management measures of this invasive carnivore. For instance, the reduced home ranges and activity rates during winter months should be taken into account in mink trapping projects. Analyses of more than 2500 scatsamples of radio tracked mink show that investigated animals principally prey on fish, small mammals and birds (eggs inclusive). There were significant seasonal variations of diet composition. In spring, the three categories of prey - fish, mammals and birds (eggs inclusive) - were hunted in similar amounts. During summer, birds and their eggs made up the main part of the diet followed by mammals. In autumn, the proportion of birds in the mink diet decreased, whereas fish gained in importance. This trend continued during the winter period, when mink preyed almost exclusively on fish. Throughout the entire year amphibians, crustaceans, insects, molluscs and reptiles were found only occasionally in scatsamples. Among birds, the mink preyed mainly on the Eurasian Coot (Fulica atra) followed by the Mallard (Anas platyrhynchos). Mammalian prey was clearly dominated by the water vole (Arvicola terrestris) and among fish, mink hunted especially perch (Perca fluviatilis), roach (Rutilus rutilus) and carp (Cyprinus carpio). Results clearly demonstrate that mink is an opportunistic predator, which hunts its prey according to availability and vulnerability, respectively. Despite the high portions of fish in the autumn and winter diet, the economic damage to fishery caused by mink seems to be low. Perch and roach were preyed on in higher frequencies than the carp which is economically relevant. However, high predation on birds and their eggs during the breeding season indicates a potential negative impact of mink on waterfowl. To summarise, it can be noted that characteristic features of the anthropogenically influenced study area affect feeding habits, activity patterns, space use and density of local mink population. In this regard the management of fishponds, which influences seasonal availability of habitat- and food resources for mink, plays an important role. American mink is regarded as “invasive”, because a negative impact on native species has been proved by several European studies. Consequently, this study recommends management with a focus on effective monitoring and, if necessary, control or exclusion measures adapted to the specific local requirements. Furthermore, to prevent additional introductions into the wild, the still existing farms have to be protected against outbreaks and liberations. In the long term, a general ban on the trade and keeping of American mink would be desirable
Der Einfluss invasiver, gebietsfremder Arten wird neben der Habitatzerstörung als eine der größten Gefährdungen der Biodiversität weltweit angesehen. Sowohl internationale Umweltvereinbarungen als auch die nationale Gesetzgebung fordern daher Maßnahmen, die eine weitere Ausbreitung bereits etablierter invasiver Neozoen verhindern und deren negative Einflüsse minimieren. Die vorliegende Studie befasst sich mit einer dieser Neozoen - dem Amerikanischen Nerz bzw. Mink (Neovison vison). Um Erkenntnisse zu Ökologie und Verhalten des semiaquatischen Musteliden in Deutschland zu gewinnen, wurden Daten zu tages- und jahreszeitlichen Aktivitätsmustern, zu Raumnutzung und Territorialsystem sowie zur Nahrungswahl und den jahreszeitlichen Unterschieden im Beutespektrum der Art erhoben. Dafür konnten in den Jahren 2003 bis 2006 in einem Fischteich-Gebiet in Mecklenburg-Vorpommern, wo sich Minke bereits seit den 1970er Jahren etabliert haben, insgesamt 14 Individuen (neun Männchen, fünf Weibchen) radiotelemetrisch überwacht werden. Anhand der Ergebnisse wird einerseits der potentielle Einfluss des gebietsfremden Raubsäugers auf einheimische Arten abgeschätzt und diskutiert. Andererseits werden die Ergebnisse herangezogen, um effektive Monitoring- und Managementmaßnahmen abzuleiten. Eine methodische Evaluation von Halsbandsendern zeigte, dass in sechs von acht Fällen die getesteten Halsbänder, die aufgrund des sehr ähnlichen Hals-Kopf-Umfanges der Individuen relativ eng angelegt werden müssen, Hautverletzungen verursachten. Infolgedessen wurden die Halsbandsender gegen durch Tierärzte operativ in die Bauchhöhle eingesetzte Implantationssender ausgetauscht. Auch bei allen nachfolgend gefangenen Tieren wurden die Sender implantiert. Bei insgesamt 14 durchgeführten Erstimplantationen beeinflussten mit Ausnahme eines Falles (Tod durch Aufbeißen der Naht) die Implantate weder das Überleben, noch die Reproduktion der Minke. Daher ist v.a. in Hinblick auf Tierschutzaspekte die Senderimplantation (in Kombination mit einer Mehrtages-Quarantäne) anstatt der Verwendung von externen Halsbandsendern zu empfehlen. Die Analyse der circannuellen Aktivitätsmuster ergab signifikante Unterschiede der saisonalen Aktivitätsraten. Während der kalten Wintermonate (Oktober bis Februar) zeigten beide Geschlechter mit durchschnittlich etwa 23 % eine vergleichsweise geringe Aktivität. Diese energiesparende Verhaltensweise war möglich, da auch im Winter ein ausreichend hohes Nahrungsangebot, vor allem an Fisch, vorhanden war. Im März kam es sowohl bei den Männchen als auch bei den Weibchen zu einem durch die Paarungszeit verursachten, beträchtlichen Anstieg der mittleren Aktivitätsraten auf fast 40 %. In den Sommermonaten (Mai bis August) waren die weiblichen Tiere, durch die Anforderungen der Jungenaufzucht bedingt, anhaltend häufig aktiv (zwischen 40 und 50 %). Die Aktivitätsraten der nicht an der Jungenaufzucht beteiligten Männchen dagegen nahmen im April wieder ab, um bis zum Juli auf einem vergleichsweise geringen Niveau von etwa 30 % zu bleiben. Sie stiegen jedoch während der Monate August und September erneut auf etwa 43 % an. Zu dieser Zeit wandern gewöhnlich die Jungtiere ab und suchen sich ein eigenes Streifgebiet (= Aktionsraum), dadurch kommt es zu Änderungen im Territorialsystem und damit einhergehenden innerartlichen Auseinandersetzungen. Beide Geschlechter unterscheiden sich stark in ihren tageszeitlichen Aktivitätsrhythmen. Alle Weibchen waren ganzjährig tagaktiv. Von den fünf untersuchten Männchen zeigten drei typische Nachtaktivität im gesamten Jahresverlauf. Die beiden anderen männlichen Tiere verhielten sich in ihren Aktivitätsrhythmen indifferent, sie zeigten das ganze Jahr über keine Präferenzen für eine bestimmte Tageszeit. Die geschlechtsspezifischen Unterschiede sowohl in den circannuellen als auch in den circadianen Aktivitätsmustern spiegeln zum einen die verschiedenen Anforderungen an die Geschlechter wieder, vor allem die Investitionen in die Fortpflanzung. Zum anderen können die geschlechtsspezifisch unterschiedlichen Zeitnutzungs-Strategien zu einer Minimierung der innerartlichen, vorzugsweise der intersexuellen Konkurrenz führen. Die Analyse der Telemetriedaten hinsichtlich Raumnutzung und Territorialsystem ergab im Vergleich zu anderen europäischen Studien relativ große individuelle Aktionsräume verbunden mit einer geringen Populationsdichte im Untersuchungsgebiet. So erstreckten sich die durchschnittlich genutzten Sommerstreifgebiete der Männchen auf 15,4 km und die der Weibchen auf 9,3 km Flusslauf bzw. Teichufer. Entsprechend dem Trend der saisonalen Aktivitätsmuster, reduzierten beide Geschlechter ihre großen Sommerstreifgebiete während der Winterhalbjahre um mehr als die Hälfte der Fläche. Allerdings nutzten die Männchen zu allen Jahreszeiten wesentlich größere Aktionsräume als die weiblichen Minke. Große Streifgebietsüberlappungen zwischen den Geschlechtern sowie verhältnismäßig niedrige Überlappungsraten der benachbarten Streifgebiete von Tieren des gleichen Geschlechts bestätigen die intrasexuelle Territorialität der Art. Die erheblichen Unterschiede der saisonalen und geschlechtsspezifischen Aktionsraumgrößen werden vermutlich durch die ermittelte, vergleichsweise geringe Populationsdichte (0,6-0,7 Individuen/km2) ermöglicht. Die ausgedehnte und sich fast über das gesamte Untersuchungsgebiet erstreckende Raumnutzung der Männchen während der Paarungszeit ist durch die Suche nach fortpflanzungsbereiten Weibchen bedingt. Die Raumnutzung der untersuchten Minke unterliegt einer hohen Dynamik, dies wird durch die häufige räumliche Verschiebung temporär stabiler Streifgebiete innerhalb einer Jahreszeit oder auch zwischen den gleichen Jahreszeiten aufeinanderfolgender Jahre verdeutlicht. All diese ermittelten charakteristischen Besonderheiten im Raum-Zeit-Verhalten der Art sollten bei der Entwicklung von Monitoring- und Managementkonzepten berücksichtigt werden. So müssen beispielsweise bei der Fallenjagd im Winter die zu dieser Zeit stark verkleinerten Streifgebiete und die reduzierten Aktivitätsraten Beachtung finden. Die Analyse der über 2500 Losungsproben telemetrierter Minke zeigte, dass sich die untersuchten Tiere hauptsächlich von Fisch, Kleinsäugern und Vögeln (inklusive deren Eiern) ernährten. Dabei traten allerdings signifikante saisonale Unterschiede in der Nahrungs-zusammensetzung auf. So wurden im Frühjahr die drei Beutekategorien Fisch, Kleinsäuger sowie Vögel und deren Eier in ähnlichen Anteilen erbeutet. Während des Sommers bildeten Vögel und Vogeleier die Hauptbeute, gefolgt von Kleinsäugern. Im Herbst verringerte sich der Vogel- und Kleinsäugeranteil im Beutespektrum zugunsten von Fisch. Dieser Trend setzte sich bis in den Winter fort; in dieser Jahreszeit ernährten sich die Minke fast ausschließlich von Fisch. Amphibien, Reptilien, Krebstiere, Insekten und Mollusken wurden im gesamten Jahresverlauf nur gelegentlich gefressen. Innerhalb der Gruppe der Vögel prädierten die Minke vor allem Blässhühner (Fulica atra), gefolgt von Stockenten (Anas platyrhynchos). Das Kleinsäuger-Beutespektrum wurde eindeutig von der Schermaus (Arvicola terrestris) dominiert und unter den Fischen erbeuteten die Minke vorzugsweise Flussbarsche (Perca fluviatilis), Plötzen (Rutilus rutilus) und Karpfen (Cyprinus carpio). Die Ergebnisse der Nahrungsanalyse bestätigen den Mink als einen opportunistischen Prädator, der seine Beutetiere je nach Verfügbarkeit bzw. dem erforderlichen Jagdaufwand nutzt. Trotz des hohen Fischanteils in der Herbst- und Winternahrung ist der durch den Mink verursachte ökonomische Schaden schätzungsweise relativ gering. Flussbarsch und Plötze wurden in höheren Frequenzanteilen erbeutet als der wirtschaftlich relevante Karpfen. Die starke Prädation von Wasservögeln und deren Eiern besonders in den Frühjahrs- und Sommermonaten weist allerdings auf einen potentiell negativen Einfluss des invasiven Raubsäugers auf diese Tiergruppe hin. Zusammenfassend lässt sich festhalten, dass die spezifischen Charakteristika des anthropogen geprägten Untersuchungsgebietes sowohl Nahrungsökologie und Aktivitätsmuster als auch Raumnutzung und Populationsdichte der lokalen Minkpopulation beeinflussen. Eine besondere Rolle hierbei spielt die Bewirtschaftung der Fischteiche, denn vor allem daraus resultiert für die Minke eine saisonal unterschiedliche Verfügbarkeit an Lebensraum und Nahrung. Negative Auswirkungen des Amerikanischen Nerzes auf die einheimische Tierwelt wurden in anderen europäischen Ländern belegt und rechtfertigen die Einstufung dieser Art als „invasiv“. Demzufolge wird in der vorliegenden Arbeit ein Management empfohlen, bei dem der Focus auf einem effektiven Monitoring und gegebenenfalls auf zweckmäßigen, an die lokalen Bedingungen angepassten Fang- oder Abwehrmaßnahmen liegt. Zudem sollten, um einer weiteren Ausbringung in das Freiland vorzubeugen, die wenigen noch existierenden Minkfarmen besser gegen Ausbrüche bzw. Freilassungsaktionen gesichert werden. Langfristig ist ein generelles Besitz- und Vermarktungsverbot für die Art wünschenswert

Historically, the tallgrass prairie (TGP) was the largest ecosystem in North America, but today only about 10-15% of the original extent exists today. Some areas have experienced more extreme loss, for example in the state of Illinois less than 0.01% of high-quality native tallgrass prairie remains. Non-native invasive species are a recent phenomenon that threatens the integrity of surviving TGP communities. Ecotypes of dominant C4 grasses are the basis of numerous cultivars, many of which are utilized in prairie restorations. In this study, the effects of three invasive species (Bromus inermis, Schedonorus phoenix, and Poa pratensis) on two lowland (`Alamo' and `Kanlow') and three upland (`Blackwell', `Cave in Rock', and `Trailblazer') cultivars of the dominant C4 grass Panicum virgatum were tested. Two simple pair-wise greenhouse experiments were established in which cultivars were sown as a monoculture or as a mixture of the cultivars with one of three invasive species. Pots were subjected to one of two water treatments with three replicates of each treatment combination. Response variables (height, number of leaves, tiller density, and biomass) and resources (soil moisture, soil pH, soil electrical conductivity, and light intensity) were measured. The greenhouse studies showed that response variables were affected by the presence of invasive species and that the time of growth affected resource levels. Resources are allocated to different areas (i.e growth and reproduction) when competition and stress are implemented on the dominant species. This study was the first to experimentally test for the presence of the physiological stress marker, trigonelline, in a prairie grass. Trigonelline was highest in upland cultivars under low moisture and highest in lowland cultivars under low moisture treatments. The results of these greenhouse studies suggest that invasive species may differentially affect cultivars of Panicum virgatum that may be sown in a prairie restoration. Performance of the P. virgatum cultivars was dependent on the timing of growth, the pot size, the invasive species, as well as soil moisture level. Therefore, when choosing a cultivar source for restoration, resources (i.e. soil moisture) should be looked into to maximize the output of the cultivar.

Predicting the locations of new biological invasions has become a high priority for biologists as well as trying to predict if newly introduced species will become damaging to native ecosystems. Reefs of the eastern oyster Crassostrea virginica in Mosquito Lagoon, Florida have been highly disturbed in recent years resulting in dead reefs (piles of dead, disarticulated shells) some of which have been restored. I conducted oyster reef surveys for non-native invertebrates to determine if disturbance on these oyster reefs might assist invasion by two species, Mytella charruana and Perna viridis, recently introduced to the southeastern coast of the United States. Next, I investigated if M. charruana's temperature and aerial exposure tolerance limits may allow for it to establish permanently on intertidal oyster reefs. Temperature and aerial exposure tolerance experiments were conducted and oyster reef temperatures were collected. Oyster reef surveys could not predict if reef disturbance is assisting in the invasion process because only two non-native individuals (P.viridis) were found, one on a restored reef and one on a natural (reference) reef. Tolerance experiments showed that some Mytella charruana survived even after 7 days of 8??C temperatures if the mussels are exposed to air for 4 hours or less per day. Mytella charruana had near 0% survival after 4 hours of 44??C. However, only disturbed reefs reached this temperature in the field. It is likely that M. charruana could survive in the low intertidal zone on restored or reference reefs. This information is important for understanding the introduction of M. charruana in Mosquito Lagoon and also provides a data set of temperature tolerances for better understanding of whether the species might be able to invade other areas.
ID: 029809008; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 64-67).
M.S.
Masters
Biology
Sciences

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol)
The Overberg renosterveld rangelands of the Cape Floristic Region (CFR) has become well associated with commercial and communal agricultural practices, namely crop and livestock production. This Mediterranean region is characterized as being a semi-arid, winter rainfall area with nutrient-limited soils. Livestock farmers rely largely on introduced legume species such as lucerne (Medicago sativa) as high quality forage to sustain their livestock’s diets. Generally, these introduced species are reliant on the accessibility of water and nutrients, due to the specific climatic and edaphic conditions of the region. The availability of high quality forage has always been a major concern to farmers when it comes to managing their livestock, since livestock productivity is determined by the quality of the forage consumed.

The emerald ash borer (EAB, Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a non-native wood boring beetle that is causing extensive ash (Fraxinus spp.) mortality in eastern North America, affecting both urban and wildland forests and drastically altering forest structure and composition. As EAB-induced ash mortality progresses, native arthropod associates of ash forests are impacted by the effects of rapid and broad scale tree mortality. These include loss of food source, increased canopy gap formation, alterations in litter inputs causing shifting temperature and moisture regimes on the forest floor, and significant accumulation of coarse woody debris. I assessed the sub-canopy arthropod community in five forests, all in different stages of the invasion process, from introduction through impact. Additionally, I assessed the ground level arthropod community in a post EAB-invaded forest with 100% mature ash mortality. Arthropod communities were assessed at the ordinal level, and with a focus on coleopterans, they were further classified to families and trophic guilds to analyze abundance, richness, and diversity. Due to their overwhelming abundance, I identified scolytines collected in the post EAB-invaded forest to species to see if the EAB-invasion was part of a greater invasional meltdown. My results indicate that the EAB-invasion in North America is affecting the native coleopteran communities associated with these forests.

Grasslands in the western United States face severe environmental threats including those brought about by climate change, such as changes in precipitation regimes and altered fire cycles; land-use conversion and development; and the introduction, establishment, and spread of non-native species. Lehmann’s lovegrass (Eragrostis lehmanniana) was introduced to the southwestern United States in the early 1900s. Since its introduction, it has become the dominant grass in the mid-elevation grasslands of southern Arizona, including the Santa Rita Experimental Range (SRER), where it has displaced native grasses including Arizona cottontop, three awns, and gramas. Like all plants in terrestrial ecosystems, this grass harbors fungal symbionts that can be important for its establishment and persistence. This thesis focuses on fungal symbionts of Lehmann’s lovegrass and has two components. First, the diversity and distributions of endophytes in Lehmann’s lovegrass are evaluated in the context of biotic and abiotic factors in the SRER. Culturing from roots and shoots of Lehmann’s lovegrass at points beneath and outside the canopy of native mesquites, which are encroaching on grasslands over time, provides insight into how a single plant species can exhibit local variation in the composition of its symbionts. Second, the thesis is used as the basis for engagement of students in science, technology, engineering, and mathematics (STEM) through the development and implementation of classroom- and field activities centered on endophytes, which help high school students address core learning aims while also gaining real research experience. Engaging students in important questions relevant to their local environment can catalyze interest in science and help students cross the threshold into research. The contributions of such approaches with respect to learning not only fulfills key next-generation science standards and common core objectives, but provides students with a meaningful introduction to the excitement, importance, and accessibility of science.

Orientador: Marcos Gomes Nogueira
Banca: Lilian Casatti
Banca: Mário Luís Orsi
Banca: Ricardo Motta Pinto Coelho
Banca: Ângelo Antônio Agostinho
Resumo: O presente estudo foi conduzido em quatro lagoas marginais da porção superior do reservatório de Rosana, bem como no canal principal do rio Paranapanema. O objetivo do primeiro capítulo foi analisar a composição e os atributos ecológicos das assembléias fitoplanctônicas, recurso trófico primário das cadeias alimentares aquáticas. O segundo capítulo trata da comunidade zooplanctônica (Cladocera e Copepoda) e sua distribuição nos ambientes analisados. O terceiro trabalho procura avaliar se a introdução de uma espécie exótica de peixe (Cichla kelberi) pode causar alterações na estrutura da ictiofauna local, com uma possível redução da sua diversidade. Por fim, o quarto capítulo refere-se à alimentação da ictiofauna de pequeno porte, através da análise da dieta e do hábito alimentar das espécies, considerando principalmente a importância da comunidade planctônica para essa fauna. O número total de táxons de fitoplâncton identificados foi de 283. Zygnemaphyta foi o grupo com maior número de espécies, seguido por Chlorophyta e Bacillariophyta. Maior riqueza, abundância e biomassa de fitoplâncton foram observadas nas lagoas, especialmente durante o período chuvoso. O número total de táxons de zooplâncton identificados foi de 72. As lagoas laterais e o período chuvoso apresentaram maior abundância de organismos. Calanoida foi o grupo dominante nas assembléias zooplanctônicas. Os resultados mostraram que no sistema de lagoas laterais as comunidades são controladas por mecanismos ascendentes ("bottom-up"). Um total de 4693 peixes, pertencentes a 43 espécies foram amostrados. A Ordem Characiformes foi a mais abundante, seguida por Perciformes e Siluriformes. Não houve diferenças estatísticas na riqueza, na abundância, na biomassa, na média do comprimento, na composição das assembléias e na diversidade de peixes, comparando-se o período... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The study was carried out in four lateral lagoons of the tail region of Rosana reservoir, as well as in the river/reservoir main channel. The aim of the first chapter of the thesis was to analyze the composition and ecological attributes of the phytoplankton assemblages, primordial trophic resource of the aquatic food chains. The second chapter is focused on the zooplankton community (Cladocera and Copepoda) and their distribution in the study environments. The third chapter tries to assess whether the introduction of a non native fish species (Cichla kelberi) may promote alterations in the local ichthyofauna, with a possible reduction in its diversity. Finally, the last chapter discusses the ichthyofauna feeding, through the analysis of diet and feeding behavior of fish, considering mainly the importance of plankton organisms as a resource. The total number of phytoplankton taxa identified was of 283. Zygnemaphyta was the most specious group, followed by Chlorophyta and Bacillariophyta. Higher richness, abundance and biomass were observed in the lagoons, especially during the rainy period. The total number of zooplankton taxa was 72. Higher zooplankton abundance was observed in the lateral lagoons and in the rainy period. Calanoids were the dominant group in the zooplankton assemblages. The results indicated that in the lateral lagoons system, the communities are controlled by bottom-up mechanisms. A total of 4,693 fish, belonging to 43 species was sampled between 2004 and 2009. The order Characiformes was the most abundant, followed by Perciformes and Siluriformes. There were no differences in composition, richness, abundance, biomass, mean length and diversity, when compared the periods previous and after the introduction of Cichla. The results showed that the feeding of the river fish assemblages was different from the lagoons... (Complete abstract click electronic access below)
Doutor

Invasive non-native species are believed to be one of the biggest threats to biodiversity. Until now biological invasions have been mainly studied from a biological perspective and much research has been undertaken to investigate species’ ecology and potential options for management. Comparatively little attention has been devoted to questions regarding the social construction of the issue. This is despite invasion biologists increasingly acknowledging the fundamental importance of human perceptions, beliefs, attitudes and values inherent in debates about invasive non-native species. This thesis employs a mix of methods from the social sciences to investigate the social construction of biological invasions. Research conducted here is based on the theory of social representations. Thus, taking a social scientific perspective, the thesis contributes to both the development of the theory and an identification of beliefs inherent in the debate on biological invasions and their relationship to people’s attitudes towards species and their management. Those species attributes that predominantly shape the debate – but yet appear to be under-researched – are identified. Based on the findings in this thesis I argue that invasion biology would benefit from a more explicit and transparent use of its concepts and terminology. This will have implications also for the communication with policy makers, conservation managers and the general public. Recommendations for future research are discussed along with limitations of the thesis.

Non-native invasive plants are destructive plants brought into places where they did occur before naturally. The rapid spread of non-native invasive plants has become an urgent threat to ecosystems at a global scale, and it is a top priority problem for natural resources management. The overall objective of this project is to predict the occurrence of some common non-native invasive plants species in Southern Illinois to allow management policies to be developed.Seventeen of the most common and abundant non-native invasive species in Southern Illinois were analyzed. Eleven environmental variables were used to model species distributions and estimate their importance to species distributions. Results showed that land cover and soil (major land resource area) were the two most significant variables related to most of focal species distributions and made the most contributions in this study. Prediction maps indicated that most species had high probabilities of occurrence at the central south and along the riversides of the Southern Illinois area. To explore how climate change affects species invasions and habitats, an ensemble of 5 commonly used atmosphere-ocean general circulation models (AOGCMs) (CanESM2, CCSM 4.0, CGCM3.0, CSIRO MK3.5, and NorESM) were used to project future climate conditions. Overall, land cover and soil types (major land resource area) were the two most significant non-climate variables related to most of focal species distributions. Species with a narrow habitat or which preferred specific habitats would be mostly affected by land cover types and soil types while species (e.g., Lonicera maackii) having wide habitat tolerance would be least impacted. Prediction maps showed that most species had distribution trends from east to west in the central south area or from central south to north east. The center of the southern part of the area dominated by the Shawnee National Forest was predicted to have the most suitable habitats for all focal species except for Humulus japonicus and Phragmites australis. The predicted distributions under climate scenarios indicated that species distributions could change or shift under different representative concentration pathways (RCPs) and potential suitable habitat might expand under climate change. Change detection was conducted to quantitatively examine how changing climate could affect invasive species’ potential habitats. The five species with the most species records were evaluated for this analysis. For these species, potential suitable habitats were most likely to expand in the central west of study area for all climate change scenarios. Species suitable habitats would shift under climate change. Functional group and phylogenetic group analyses were conducted to investigate how species groups affect species spatial distributions and how evolutionary related nonnative invasive species distribute spatially. The 17 focal species were grouped into 4 broad functional groups (Woody and shrub species -FG1, herbaceous species -FG2, grass species -FG3, and vine species -FG4) based on life form. AUC indicated that model performance of functional groups was no better than of individual species alone. Land cover was the variable with the largest variable contribution to the predicted distributions of FG1, FG3, and FG4 while maximum temperature had the largest contribution for FG2. Composite maps for the functional groups showed that the central south dominated by the Shawnee National Forest was predicted as the most suitable habitats for all four functional groups. The composite maps for these functional groups were similar to the maps for the individual species within each own functional group. Genetic sequences of each species were used to construct a phylogeny. Besides the 17 focal species, an outgroup species Berberis vulgaris was added into the model to root the phylogenetic tree. Based on the resulting phylogenetic tree, species were classed into 3 groups (superasterids-PG1, monocots-PG2, and superrosids-PG3) based phylogenetic relativeness and distance. AUC indicated that model performance of phylogenetic groups was no better than of individual species alone. Variable contributions of functional groups indicated that landcover was the most significant variable for all three PGs. Composite maps showed the central south was predicted as hotspot. Phylogenetically related species responded similarly to the single species. This study focused on the prediction of non-native invasive species distributions in relation to environmental variables. Environmental factors that significantly affect invasive species distributions can indicate natural resource managers when conducting invasive species management is necessary. The approach of studying how invasive species respond to climate change can be extended to other invasive species research. By integrating functional groups and phylogenetic groups into species distribution predictions, species with too few records for modeling can be examined with abundant species in the same functional or phylogenetic group in predicting distributions. However, this research did not study how interspecific interactions (i.e, competition) between native and invasive species would affect species invasion. Further research of intergrating biotic factors is needed.

Experience has shown that effective fisheries governance requires a sound understanding of fisheries as systems incorporating both ecological and human dimensions. The Ecosystem Approach to Fisheries requires that the human components of these systems be considered when developing management and governance frameworks. While the potential for inland fisheries to contribute towards societal welfare and the development of rural livelihoods is becoming increasingly apparent, developing South African inland fisheries requires a careful consideration of both their positive and negative impacts, given that they revolve mainly around five of the world‟s top 100 invasive species. This thesis aimed to explore the value of inland recreational fisheries to rural livelihoods in the Amathole District of South Africa, to the regional economy, and to anglers themselves. Three methods were used to isolate this value. Economic impact analysis was used to estimate the combined total economic impact of the 2011 Divisional Tournament (n=31) and the 2012 Amatola Bass Classic (n=100) on the regional economy of the Amathole District, estimated to be R106 625. The travel cost method was applied to data from the 2012 Amatola Bass Classic in order to estimate the social welfare generated by this tournament. The Negative Binomial model, corrected for truncation and endogenous stratification, estimated this value at R 1 960 090. The sustainable livelihoods framework was used to conduct a broad-based analysis of the value of Amatola Wild Trout, the firm which constitutes the fishery surrounding the rural village of Cata. It was found that the fishery had been responsible for a modest pecuniary impact on the community of Cata within its first two years of establishment, although significant improvements in human capital were found to have resulted from the development of the fishery. These results provide insights into the economic dimension of fisheries in the Amathole District, and will prove useful when weighing up the positive and negative impacts of non-native fish species, particularly when informing decisions regarding their potential eradication.

Human transport of species around Earth has led to the intentional and accidental introduction of many species into new regions. Introduced species can have significant impacts outside their native ranges, with a range of positive and negative ecological effects on native biota, community productivity and nutrient cycling. Climate and land use are major determinants of non-native species distributions, with climate setting the broad limits to plant distribution and productivity, and with human activity associated with different land uses affecting the dispersal and success of introduced species. There is potential for future changes in land use and climate to have an impact on distributions of non-native species, due to possible changes to transport, establishment and spread. This thesis uses records of plant species in Britain to determine patterns of non-native species richness with climate and land use, predict possible changes with climate change, quantify establishment of non-native species and to examine levels of establishment for groups of non-native species with different traits (Plant Functional Types). Models were used to examine the relationship between species richness of non-natives and natives with climate variables and land cover types, and projected climate data was used to predict possible future changes. An establishment index was calculated to quantify establishment of non-native species; it was found that date of introduction and range size are not necessarily good predictors of level of establishment and that well established species are less likely to be associated with urban areas than poorly established species. Distributions and establishment of Plant Functional Types were examined, showing that some groups have distinct patterns with land cover related to where they are most likely to be introduced. The least established groups show greater associations with land cover than with climate. Climate and land use changes have the potential to allow new species to establish and to allow already established species to spread due to shifts or expansions in their potential climatic ranges. Future studies of non-native species should attempt to distinguish between time since arrival and the level of establishment because the two may not be associated.

The dominant competitive abilities of many invasive species are frequently assumed to preclude biologically similar native species over time, but there has been little research exploring how interactions between invasive and native species may change with changes in biotic and abiotic conditions. Introduction of the invasive New Zealand mud snail Potamopyrgus antipodarum in the Snake River in the late 1980's raised many concerns for the native gastropods of this region; however, the native gastropod Valvata humeralis has maintained large populations and continued to coexist with P. antipodarum. I investigated the coexistence of P. antipodarum and V. humeralis in the Vista reach of the Middle Snake River. Diet, spatial, and temporal partitioning of V. humeralis were explored in populations that were invaded by P. antipodarum and uninvaded. A field growth experiment was used to measure the net intra- and interspecific effects of V. humeralis and P. antipodarum at varying densities and species proportions. Results of the field growth experiment were compared with field survey data. A laboratory growth experiment and a stoichiometric experiment were used to identify the interaction mechanisms between species. Valvata humeralis juveniles appeared to shift diet in the presence P. antipodarum. There was evidence of spatial partitioning from P. antipodarum by V. humeralis at the among population scale but not the within population or patch scales. The field growth experiment indicated that interspecific net effects of P. antipodarum on V. humeralis changed in direction with increasing P. antipodarum density. Field surveys showed a similar pattern. The laboratory growth experiment indicated that direct interference competition was the negative mechanism of the species interaction and confirmed field experimental results. Stoichiometric analyses suggested that P. antipodarum juveniles require more phosphorus than V. humeralis juveniles, but that stoichiometric facilitation was not likely an interaction mechanism. Facilitated growth of V. humeralis in the presence of P. antipodarum may have been caused by increased access to food and/or P. antipodarum digestive food conditioning. Results suggest that the impact of an invasive species on the native community may be a complex interplay between invader density, native species behavior, invader nutrient use, and environmental conditions. 'Co-authored by Billie. L. Kerans.'

Non-native plant species are increasingly being viewed as a threat to sub-alpine and alpine ecosystems, and the need to determine the causes and mechanisms of non-native plant invasions in mountain systems has been recognized. This study was initiated to provide: 1) useful information for managers in the local area and, 2) information that can be used in concert with data from similar studies to help elucidate the causes and mechanisms of non-native plant species invasions in mountain systems at the global scale. Eighteen populations a non-native species (Linaria dalmatica) and 14 populations of a closely related native species (Castilleja miniata) were surveyed along an elevation gradient in the Greater Yellowstone Ecosystem. Climate, environmental, and species demographic data were collected from each site from 2008-2011. Climate and environmental predictors varied along the elevation gradient, with stem density of the two test species being explained by different sets of predictors. Vital rates of L. dalmatica were found to be more variable and more highly associated with climate and environmental predictor variables than those of C. miniata. The population growth rate of L. dalmatica did not show any consistent trend with elevation, but did appear to be influenced by extremely cold temperatures and predictors related to the vegetative community. Probability of occurrence of L. dalmatica was related to elevation. Percent cover of L. dalmatica was not associated with elevation, instead being strongly associated with vegetative community characteristics such as percent perennial cover. The current range of L. dalmatica was broader than the majority of native species in the study area, and the non-native plant community in the study area was significantly more nested with increased elevation than the native plant community. These results suggest that L. dalmatica is a broadly adapted species. Overall, our data fail to provide conclusive evidence of climatic limits for this species, but suggest that it may be limited from upward expansion by extremely cold winter temperatures. Until conclusive evidence of climatic limitation is provided, the upper populations of this species should be monitored and managed to prevent further spread into sub-alpine/alpine environments.

Novel environments and biological communities created by the large-scale deployment of Marine Renewable Energy Devices (MREDs) have the potential to promote the spread of non-native species (NNS). Knowledge of how community composition resident on MREDs is shaped by geography, local hydrodynamics and the duration of deployment, will clarify how these technologies will interact with natural habitats, including the provision of suitable habitat for NNS. A network of navigation buoys was used to study biofouling communities in areas proposed for MRED deployment. Significant differences in community structure were observed in different geographic areas. A significant reduction in number of taxa present and community wet-weight was observed where buoys were deployed in greater tidal flow rates. However, overall community composition was not significantly different between ‘high’ (>1 ms-1) and ‘low’ (<1 ms-1) flow areas and for buoys deployed for different time durations (1-7 years). These finding have important implications for the longevity of devices and their interaction with natural habitats, including proposed ‘artificial reef’ effects. In total five non-native species were identified on the buoys sampled, supporting the need to monitor MREDs as the industry grows. Hydrodynamic and biotic features of the epibenthic communities were used to predict the presence of the most prevalent NNS, the amphipod Caprella mutica, in addition to other native amphipod species. Caprella mutica presence was found to be significantly affected by increasing flow speed compared with the native amphipod Jassa herdmani. Behavioural flume studies investigating flow-related processes governing the presence of non-native amphipods supported these findings. This study details how the hydrodynamic and biological environments created by MREDs determine their suitability for the establishment of self-sustaining populations, and therefore their dispersal potential for NNS. These findings inform design criteria and management options to minimise the biosecurity risk that these structures will pose as the industry expands.

Invasive Non-Native Species (INNS), or Invasive Alien Species, are organisms introduced by humans outside their natural range that have “negative impacts on biodiversity, socio-economy or human health”. Growing awareness of the ecological and socio-economic impacts of INNS has led to a mushrooming of control attempts across the UK. The costs of such environmental management has grown far in excess of the availability of funds to afford control by professionals and led to widespread involvement of volunteers in INNS management and monitoring. This thesis aimed to identify challenges in collaborations between lay people and experts in ecological restoration and to critically examine some of the claims made about the benefits of citizen participation on the sustainability and democratisation of environmental management and on citizen empowerment. Qualitative research methodology was employed to explore in depth motivations, experiences, intentions and views of volunteers and of the organisations that attempt to enrol them in practical conservation work and monitoring activities. We found that caring for nature, the experience of nature and the activities, and social interactions were the three main drivers of volunteering. Importantly, over time, motivations were shaped by the interplay between individual expectations and experiences with the social and ecological context and changed from identifiable personal goals and functions to more complex attachments to the place and the group. Our research also revealed that while some of these key motivations may be recognised by project managers, their description of costeffectiveness, local ownership and empowerment as complementary volunteering goals were often not aligned in practice. Moreover, decision-making may remain largely expert-based, with volunteers not perceiving their knowledge to be valid or a useful contribution to decision-making. Enhancing the sustainability and democratic nature of INNS management requires reflexive practice of citizen engagement that explicitly considers different interests and views but also invites citizens to reflect on their role in the co-production of conservation practice and knowledge.

The Puerto Rican coqui frog, Eleutherodactylus coqui, was introduced to Hawaii in the late 1980s via the commercial horticulture trade. Previous research has shown that coquis can change invertebrate communities, but these studies were conducted at small scales using controlled, manipulative experiments. The objective of this research was to determine whether coqui invasions change invertebrate communities at the landscape scale across the island of Hawaii. At each invasion front, we measured environmental variability on either side of the front and removed sites that were too variable across the front to ensure that the impacts we measured were the result of the invasion. After doing this, there remained 15 sites for which we compared invertebrate communities in 30 m x 30 m plots situated on either side of coqui invasion fronts. In each plot, we collected invertebrate samples from three invertebrate communities, the leaf litter, foliage, and flying invertebrate communities. Multivariate analyses show that coqui frogs change leaf litter communities, by reducing microbivore and herbivore abundances. Coqui also change flying community composition, but have no measurable effect on foliage communities. Across sites, we found that coquis reduced the number of leaf litter invertebrates by 27%, and specifically abundant Acari by 36%. We also found that coquis increased the abundance of flying Diptera by 19% across sites. We suggest that the leaf litter community is altered through direct coqui predation and that Diptera increase because of increased frog carcasses and excrement in invaded plots. Results support previous studies conducted in more controlled settings, but add to our understanding of the invasion by demonstrating that coqui effects on invertebrate communities are measurable at the landscape scale.

Doutoramento em Engenharia do Ambiente / Instituto Superior de Agronomia. Universidade de Lisboa
Horticulture industry uses peat as the main constituent in growing media formulations due to its ability to support efficient plant production. However, peat is a non-renewable resource at its actual extraction rate, and environmental issues associated with greenhouse gases emission from peat harvest raised peatland ecosystem conservation awareness through environmental initiatives, organizations and politics worldwide, limiting its use. There has been an increasing demand for environmentally friendly peat alternatives focused on locally available, organic and renewable materials from industrial side-streams, mainly wood-based and forest biomass. Therefore, woody raw-materials physical, chemical and biological properties are important to determinate further pre-treatment identification and choice. This work evaluates bark-based growing media suitability from non-native forest species in Mediterranean region, Acacia melanoxylon – residual biomass from invasive species control – and Eucalyptus globulus – a pulpwood industrial waste-stream. Ageing, a zero-waste treatment, allowed A. melanoxylon mature bark to effectively replace half of container medium volume as peat alternative. Low-temperature hydrothermal treatment, a faster process, enabled E. globulus bark to substitute quarter container medium volume, ensuring equal plant performance as commercial material. Both raw-materials sieve size manipulation promoted its incorporation as aeration growing media component. Given the wood-based raw-materials nature, Nitrogen amendment should be provided according to plant and cultivation system’s needs. Furthermore, by replacing the ‘end-of-life’ biomass material into new potential horticultural products, circular economy approach was applied throughout this study. Thus, A. melanoxylon juvenile bark extracts phytotoxic effect showed a promising non-synthetic and natural bio-herbicide for weed control. In response to the potential circularity of invasive species biomass resources into add-value horticultural products, the present study outcome underlines Acacia species biomass commercial valorisation as alternative management tool to support the costs of control, avoiding the potential risk of conflict between economic exploitation and negative environmental impact
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Flower seed mixes are increasingly used to enhance the biodiversity and amenity values of urban green spaces. Urban or “pictorial” flower seed mixes are often used because they are designed using cultivars and non-native species to provide more colourful and longer-lasting flower displays. Although these seed mixes are effective in providing a high density of large colourful flowers, over an extended season, their value for biodiversity, and in particular the floral rewards they provide for flower-visitors, is largely unknown. The overall aim of my thesis was to assess and improve the value of these new urban habitats as forage resources for flower-visiting insects. My approach was to quantify and compare floral reward provision and insect visitation between meadows grown from three exemplar commercial pictorial flower meadow seed mixes (called Marmalade Annual, Short Annual and Cornfield Annual). I also compared these standard commercial mixes with corresponding ‘nectar-enriched’ formulations, which were designed by increasing the proportional seed weight contribution of selected species predicted to produce high quantities of nectar within each mix. To compare floral rewards and visitation between meadows grown from these seed mixes, I set up a field experiment in Sheffield, UK, using a complete randomised block design with six replicate blocks, each with six 25 m2 plots sown with one of the six seed mix treatments. My first objective was to quantify the floral nectar and pollen rewards provided by each flowering species recorded in the meadows (on the scale of a single flower or inflorescence). My second objective was to use these data to quantify the floral rewards provided per unit area by replicate meadows of different seed mix treatments, testing whether enrichment of seed mixes is an effective method of increasing floral nectar sugar rewards. My third objective was to corroborate/correct my morphology-based flower-visitor identifications using DNA barcoding to screen for misidentifications and morphologically cryptic species. I then used these DNA barcode-based identifications to assess whether there are systematic biases in the structure of flower-visitor networks constructed using molecular taxon identifications compared to traditional morphology-based taxon identifications. My fourth objective was to quantify patterns of insect visitation to meadows, testing whether meadows of different seed mix types attract different flower-visitor assemblages. Meadow floral composition surveys revealed that contamination by unintended horticultural species was widespread across replicate seed mix treatments, with contaminants likely germinating from a seed bank laid down during a failed attempt at this experiment the previous year. Contamination particularly affected Marmalade mixes, mainly because the common contaminant species were often also components of the Short and Cornfield mixes. For example, contaminants contributed on average about a third of nectar sugar mass or pollen volume per unit area in Marmalade mix meadows. Hence, contamination fundamentally undermined the internal validity of seed mix treatments, reducing the ability to directly attribute meadow level patterns in floral rewards or flower-visitors to seed mixes. As result, examination of patterns of floral resource provision and insect visitation were more informative at a species scale. In terms of patterns of insect visitation, Centaurea cyanus received 91% of bumblebee visits, 88% of honeybee visits and 29% of hoverfly visits, whilst T. inodorum received 27% of hoverfly visits. Patterns of bumblebee and honeybee visitation indicated preferential visitation to floral units of Centaurea cyanus. Although this species produced high quantities of nectar sugar mass and pollen volume, this did not differentiate it from other Asteraceae, such as Glebionis segetum, Rudbeckia hirta and Coreopsis tinctoria, which all produced high quantities of both floral rewards. Hence, it is likely that floral traits not measured in this study, such as nectar accessibility (‘nectar-holder depth’) or concentration/volume characteristics (which can affect accessibility due to constraints imposed by feeding morphology), drove patterns of preferential visitation in bumblebees and honeybees to C. cyanus. Given that in the absence of contamination there would have been very few bumblebee or honeybee visitors to Marmalade mix meadows, aesthetically designed pictorial meadows can fail to jointly provide benefits for people and some important flower-visiting insect taxa. DNA barcoding did not change specimen identifications for most morphotaxa. However, splitting and/or lumping processes affected almost one third of morphotaxa, with lumping of morphotaxa the most common type of change. This was in part because males and females from sexually dimorphic species were often separated by morphological identification. These DNA barcode-based changes to visitor taxonomy resulted in consistent minor changes in network size and structure across replicate networks. Lumping of morphotaxa decreased taxon richness, reducing the number of unique links and interaction diversity (the effective number of links). Lumping also increased flower-visitor generality, reducing plant vulnerability and increasing overall network connectance. However, taxonomic changes had no effect on interaction evenness or network specialisation. Thus, for this well-studied fauna, DNA barcode-based flower-visitor networks were systematically biased toward fewer taxa and links, with more generalist visitors and specialist plants. Given that many tropical faunas have more species and are less described than in Britain this pattern may not be replicated in other studies. Further studies in contrasting plant-pollinator communities are required before generalisations can be made about systematic biases between networks constructed using morphological versus molecular data. Overall, meadows grown from annual pictorial flower meadow seed mixes provide abundant floral units per unit area of meadow and are a valuable alternative to traditional horticultural flower beds or amenity grasslands in high profile urban contexts. Nevertheless, care must be taken during design of seed mixes and selection of mixes for planting to ensure that species in the mix provide suitable floral resources for an array of flower-visitors, including bees. This would be aided by the integration of informative measures for candidate species of floral rewards or visitor types and visitation rates during seed mix design.

As consequências ecológicas da introdução de espécies exóticas, é uma das questões de conservação mais preocupantes mundialmente. A utilização de dados de ciência cidadã, tem sido proposta como uma solução alternativa para analisar este problema. Assim, o nosso principal objectivo foi avaliar a adequabilidade de dados de ciência cidadã para monitorizar as tendências populacionais e de distribuição de espécies exóticas (Psittaciformes and Sturnidae) na região urbana de Lisboa, utilizando três principais grupos de fontes de dados. Estes dados foram validados, uma vez que foram recolhidos por colaboradores experientes, a quantidade de registos foi considerável, e os padrões espácio-temporais relativamente homogéneos. Entre as oito espécies mais registadas, o periquito-rabijunco e o mainá-de-crista, tiveram o maior aumento populacional e de distribuição. Para o periquitão-de-cabeça-azul, foi igualmente registado um aumento, mas menos marcado, enquanto as restantes espécies registadas ocasionalmente. Desta forma, a ciência cidadã demonstrou ser uma ferramenta útil alternativa à ciência convencional; Abstract: The ecological consequences from the introduction of non-native species are among the major conservation concerns worldwide. Using citizen-science data has been proposed as an alternative solution to asses this problem. Thus, our main goal was to evaluate the suitability of citizen-science data to monitor the population and distribution trend of non-native species (Psittaciformes and Sturnidae) in the urban region of Lisbon. The evaluation included three major groups of data sources. We validated the suitability of citizen-science data since the contributors' expertise is in general high, the amount of records is considerable, and the spatio-temporal patterns are relatively homogeneous. Among the eight most recorded species, the Ring-necked Parakeet and the Crested Myna showed a noticeable increase in population and distribution range. The Blue-crowned Parakeet also increased but less markedly, while for the remaining species there were only occasional records. Therefore, the citizen-science showed to be a valuable alternative to conventional science.

As bacias hidrográficas mediterrânicas, são consideradas importantes hotspots de biodiversidade piscícola, no entanto encontram-se sujeitas a elevada pressões antrópicas, nomeadamente devido à introdução de espécies piscícolas não-nativas. O presente estudo tem como objectivo determinar os padrões de abundância e riqueza de espécies piscícolas nas bacias hidrográficas do Sul de Portugal e avaliar a contaminação biológica e risco de bio-poluição causado por não-nativas, como também identificar os factores ambientais, incluindo pressões antropogénicas, que determinam os padrões de bio-contaminação. A densidade, a proporção, o número de espécies não-nativas assim como os índices de contaminação biológica foram superiores em locais degradados relativamente aos locais de referência, os quais apresentaram maior número de espécies nativas. A bacia do Sado destacou-se das restantes bacias com maiores valores médios de contaminação biológica e risco ecológico de bio-poluição devido a apresentar condições ambientais e de pressão antropogénicas favoráveis para o sucesso do estabelecimento de um grande número de espécies não-nativas introduzidas em Portugal. As bacias do Mira e das Ribeiras do Algarve apresentaram relativamente baixa contaminação biológica e risco ecológico por bio-poluição, devendo ser alvo de programas de prevenção para potenciais invasões. Os factores de invasibilidade estão relacionados tanto com aspectos ambientais puros, que tendem a variar de bacia para bacia e de espécie para espécie, como com o nível e o tipo de pressão antropogénica, que em conjunto, potenciam o sucesso de invasão das espécies não-nativas; Biological contamination of freshwater fish Mediterranean type streams: geospatial factors of invasibility Abstract Mediterranean basins are important fish biodiversity hotspots, however are subject to high anthropogenic pressures, particularly due to introduction of non-native fish species. This study aims to define patterns of fish species abundance and diversity in the river basins of southern Portugal and evaluate the biological contamination and bio-pollution risk caused by non-native species, but also identifies the environmental factors, including anthropogenic pressures, which determine biological contamination patterns. Non-native species density, proportion, number as well biological contamination indexes were higher in disturbed sites in relative to reference sites, which showed large number of native species. The Sado basin stood out from the other basins with higher mean values of biological contamination and ecological risk of bio-pollution because of environmental and anthropogenic pressure favorable conditions for the successful establishment of a huge number of non-native species introduced in Portugal. Mira and Ribeiras of Algarve basins showed relatively low biological contamination and ecological risk for bio-pollution, must be the prevention programs focus for potential invasions. The invasibility factors are related to pure environmental features, which tend to differ from basin to basin and from species to species, as well with the anthropogenic pressure level and type, which together increase the success of invasion by non-native species.

Abstract The popularity of nature-based tourism has increased worldwide and peripheral areas with conservational value, like protected areas, are attractive destinations. The recreational use and construction of tourism facilities can cause environmental degradation and decrease the conservational and recreational value of areas if not well planned and managed. The aim of this thesis was to improve our knowledge of recreation and tourism induced changes in northern boreal environments. Direct and indirect impacts of recreation on vegetation and birds in protected areas were examined. Furthermore, the environmental impacts of ski resorts in terms of changes in vegetation and soil, threats from non-native species and water pollution were investigated. In protected areas, the size of the disturbed areas around campsites was found to be mainly determined by the distance between the main tourism facilities (wilderness hut and campfire-site), and the mountain biotopes were more sensitive to disturbance than forests. Recreational use had induced changes also in the bird community. The occurrence and the composition of birds were affected, and the open nesters nesting on the ground were found to be the most sensitive. The construction, revegetation and management practices of ski runs had increased the nutrient concentrations, pH and conductivity of the soil, and changed the original vegetation notably. Non-native seed mixture species, used in revegetating the ski runs, were found to be favoured by management practices (disturbance and peat addition) in an experimental study, but, eventually, were not able to be established themselves into study plots. Ski resorts’ construction and management have also affected the water quality. Concentrations of nutrients were higher in ski resort lakes in relation to reference lakes and were comparable to lakes polluted by agriculture and forestry. The results of this theses give new information on tourism and recreation induced changes and are applicable for planning and management. Nature-based tourism and recreation can cause long-term changes in terrestrial and aquatic environments, which should be considered at all levels of planning and management. For sustainable tourism development, it is essential that impacts are regularly monitored and preventative means are developed and used to minimize environmental degradation.