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.

This study assesses the impacts of the invasive oil-collecting bee Centris nitida on the established endemic mutualism between Byrsonima lucida and Centris errans its sole native pollinator. In natural pine rocklands and urban areas, I examined the breeding system of B. lucida, assessed the degree of its pollen limitations, and compared the key processes of pollination for the Centris bees. Breeding system results showed that B. lucida was self incompatible and pollinator dependent. Pollen limitation treatments suggested that B. lucida is pollen limited, regardless of the contributions of the invasive bee. The native bee had significantly higher visitation rates to B. lucida plants, but had a lower foraging rate and was the less efficient pollinator. The invasive bee appears to be more common in urban environments. Further understanding the nature of these novel relationships is vital for the conservation of B. lucida and integrity of pine rocklands.

Understanding the mechanisms of invasion is critical in order to control an invasive species. Poa pratensis L. (Kentucky bluegrass) is an invasive species that has been present in the northern Great Plains (NGP) for over 100 years, but has become a dominant species in the mixed grass region recently. My dissertation seeks to answer one critical question—why has P. pratensis become such a successful invasive species in the NGP? I first asked if the invasion was caused by adaptation and/or propagule pressure. I screened the genetic fingerprint of invasive P. pratensis in the NGP along with measuring the genomic content of wild plants and compared them to common cultivars. I found virtually no overlap between lawn cultivars and invasive P. pratensis populations. This was further supported by a narrow range of genomic content in wild individuals compared to the lawn cultivars. I also found no evidence of geographical patterning which is consistent with the hypothesis that local adaptation is not pervasive in P. pratensis. I then asked whether P. pratensis was a strong competitor compared to dominant plant species native to the tallgrass prairie. I studied competitive effect between Poa pratensis, Nassella viridula, Pascopyrum smithii, and Bouteloua gracilis through a species-pair competition experiment. Based on the relative interaction indices, P. smithii and P. pratensis were competitive against B. gracilis, and P. smithii was competitive against N. viridula. Additionally, P. pratensis was facilitated by all three species in the experiment. This study indicates that P. pratensis may be somewhat competitive. Finally, I asked whether the increase in the frequency of P. pratensis in the NGP may be attributed to environmental factors. In order to understand long-term correlations between P. pratensis invasion and environmental variables, I resampled plots that were previously sampled for species composition in 1978, 1979, and 1999. I found that P. pratensis levels did increase across plots and was corrrelated with higher levels of precipitation. My research indicates that increased precipitation in the NGP as a result of climate change is correlated with P. pratensis invasion in the NGP. / United States Fish and Wildlife Service (FWS-R6-POAPRATENSISGENETICS) / North Dakota State University. Department of Biological Sciences / North Dakota State University. Department of Natural Resource Management / North Dakota State University. Graduate School / Cross Ranch Fellowship

Biological invasions represent both an urgent conservation problem and an opportunity to advance ecological theory. Development of pertinent research questions and proactive management strategies require knowledge of which introduced species are present and of spatiotemporal trends in the distribution of natives and invaders. In Chapter 2 we developed a quantitative framework to identify spreaders and decliners and estimate invasion chronologies based on a historical fish presence data set for upper and middle New River (UMNR) tributaries. Our framework accounts for spatiotemporal variability in sampling effort by aggregating presences by watershed and expressing range size as a function of the number of watersheds sampled per time period. The majority (55%) of fish species present in the study area were introduced, 51% of which were spreaders. Most spreaders (84%) appeared to be spreading exponentially. The rate of new introductions detected in the study area has slowed since the mid-20th century. Two natives, the mound-spawning bluehead chub Nocomis leptocephalus and its strong nest associate (reproductive mutualist), mountain redbelly dace Chrosomus oreas, were among the most rapid spreaders. Four natives showed evidence of decline. Our framework leverages historical presence data to reconstruct temporal trends in species distributions. It sets the stage for further study of factors driving stream fish invasions and declines in the Appalachian region, and is transferable to diverse taxonomic groups and geographic regions. Species traits and human activities mediating stream-fish invasions remain poorly understood. In Chapter 3 we modeled the contribution of species traits to invasion success of UMNR tributary fishes during the colonization and spread stages. Biological traits accurately explained colonization and spread success, whereas ecological traits resulted in less accurate models. Colonization success was positively related to time since introduction, benthic feeding, an equilibrium life history, and nest spawning. Successful spread was positively related to winter air temperature in the native range and an equilibrium life history. Variables estimating human use and propagule pressure were non-informative. Traits that influenced invasion success were consistent with the hypothesis that human land-use practices have increased the invasibility of highland watersheds by creating novel conditions suited to lowland and equilibrium invaders. / Master of Science

Since globalization have promoted the ornamental trade and accelerated the movement of freshwater fishes around the world, non-native species pose a high potential to be released into local freshwater habitats, and to spread and establish as invasive and nuisance species with adverse ecological, economic and social impacts. This study aimed to investigate the potential of the ornamental freshwater fish trade as an invasion pathway in Hong Kong, assess the ecological risk of common aquarium freshwater fish species being traded in the local market, identify species of concern and recommend ways for their management with a view to minimizing biological invasion risk associated with the aquarium trade. Based on a series of systematic market surveys through visiting 46 major aquarium shops in Hong Kong, about 167 freshwater fish species were found in the local aquarium trade between summer 2012 and spring 2013. Twenty-five species were randomly selected to go through two standard ecological risk assessment protocols (i.e., FISK & IFRA). The assessment results indicated that the goldfish (Carassius auratus), common carp (Cyprinus carpio carpio) and Wel’s catfish (Silurus glanis) have a high invasive risk in Hong Kong. The ornamental trade is one of the significant sources of freshwater fish invasions in Hong Kong. An integrated invasive species management plan is recommended to apply and implement in Hong Kong. The key elements of this management plan include (1) development of law and regulation on invasive species, (2) establishment of an early detection programme (like the current study), (3) implementation of control and eradication measures, (4) setting up invasive species handling guidelines and (5) fostering public education programs on biological invasion prevention. The plan should involve the participation of all stakeholders, such as government, industry, social community organization and public in order to engage them to jointly effectively tackle and manage invasive species and thereby conserve Hong Kong’s aquatic biodiversity. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Globalization has seen an unprecedented dispersal of exotic and alien species worldwide resulting in worldwide homogenization and sometimes extinction of indigenous or endemic taxa. When an exotic species becomes established in a new habitat the invasive organisms are capable of having an impact on indigenous community dynamics and the overall structure and function of ecosystems. Furthermore, the impact of invasion is determined by the geographical range, abundance and the per-capita or per-biomass effect of the invader. However, the success of the introduced organisms is reliant on their ability to acclimate to the physiochemical conditions of the newly invaded environment.Freshwater ecosystems are especially vulnerable to invasions because there are numerous potential routes of introduction including intentional pathways such as stocking, and unintentional pathways such as the release of ballast water and aquarium releases. Efforts to limit the introduction of invasive species or to manage established exotic populations are often hindered by insufficient understanding of the natural history of problematic species. Relatively little is known regarding the physiological tolerances of many taxa. Knowledge about specific species ecophysiological constraints allows for the prediction of future patterns of invasion more accurately, including where an introduced organism would probably survive, thrive and disperse. Furthermore, data on the physiological tolerances of an introduced exotic organism may provide data necessary for effective management and control. This studyinvestigated three invasive species in the Nseleni River system in a protected area in KwaZulu-Natal. The species studied were, Tarebia granifera (Quilted melania – Lamarck, 1822), Pterygoplichthys disjunctivus (Suckermouth armoured catfish - Weber, 1991) and Eichhornia crassipes (water hyacinth – (Martius) Solms-Laubach,). The Nseleni River flows into Lake Nsezi which is responsible for providing potable water to the surrounding towns and industry, as well as the surrounding rural communities. The Enseleni Nature reserve has become the centre for biodiversity dispersal in the immediate area, due to the change in landscape surrounding the protected area.An important step in developing alien invasive species management strategies in protected areas is determining their extent and invasive traits. Tarebia granifera is a prosobranch gastropod originally from South-East Asia that has become invasive in several countries around the world including South Africa. Snail populations were sampled at nine sites throughout the Nseleni/Mposa river system every six weeks over a twelve month period. The snail was abundant throughout the system, especially in shallow waters of less than 1m in depth.The first positive identification the loricariid catfish Pterygoplichthys disjunctivus for the Nseleni River was in 2006. The original introduction is believed to have been via the aquarium trade. The aim of the study was to assess the usefulness of the unified framework with regard to management of fish invasions by assessing the invasion stage of the loricariid population and identifying appropriate management actions using the Blackburn et al. (2011) framework. The fish were sampled at nine different sites and three different depths over a period of twelve months, as well as when two ichthyological surveys were carried out on the Nseleni River system. This invasive fish has been located throughout the system and both male and female fish were collected. The smallest fish sampled was a fingerling of a day or two old and the smallest pregnant female was a mere 270mm TL. This is a clear indication that this fish is breeding in the river system.Although T. granifera and P. disjunctivus were abundant in the Nseleni/Mposa river system, it was not clear what their role in the system was, and in particular if they were competing with any of the indigenous species. Therefore, isotope samples were collected from numerous taxa over a two week period, with the exception of Pterygoplichthys disjunctivus samples, which were collected over 12 months. The δ13C and δ15N signatures of all samples were determined. The niche overlap between the invasive and indigenous snails was effectively zero (1.02E-13%), indicating no shared food resources. The medium ranges of dNRb (7.14) and dCRb (9.07) for the invasive fish indicate that it utilizes a wider range of food resources and trophic levels than the majority of indigenous fish. A medium CDb value (2.34) for the invasive fish species, P. disjunctivus, describes medium trophic diversity, with three indigenous species possessing higher diversity and three possessing lower diversity. Furtherresults indicated that there was no direct dietary competition between P. disjunctivus and indigenous species. Eichhornia crassipes was first recorded on the Nseleni River in 1978, and has been shown to have a significant negative impact on the biodiversity of the Nseleni/Mposa River system and therefore required a control intervention. Although biological control using the two weevil species Neochetina eichhornia (Warner) and N. bruchi (Hustache) has been credited with affecting a good level of control, the lack of a manipulated post-release evaluation experiments has undermined this statement. Five experimental plots of water hyacinth of 20m2 were sprayed with an insecticide to control weevils. After ten months the plants in the sprayed plots were significantly bigger and heavier than those in the control plots that had natural populations of the biological control agents. This study has shown unequivocally that biological control has contributed significantly to the control of water hyacinth on the Nseleni/Mposa River system.The management plan for the Enseleni Nature Reserve identifies the need to control invasive and/or exotic organisms within the boundary of the protected area. In addition, set guidelines have been implemented on how to control these organisms, so that indigenous organisms are least affected. Lack of control of exotic organisms can have serious consequences for indigenous species. It is therefore of utmost importance that the population dynamics of the invading organism be understood, what the potential impact could be and how to control them. Furthermore, it has also acknowledged the threat of possible exotic species invasions from outside of the protected area that might result in threats to the protected area and that these must be investigated, researched and managed.This thesis has identified Tarebia granifera, Pterygoplichthys disjunctivus and Eichhornia crassipes as being a threat to indigenous biodiversity within the protected area, as well as in adjacent areas to the protected area. The thesis will therefore investigate the hypothesis that both Tarebia granifera and Pterygoplichthys disjunctivus are having a direct negative effect on available food resources for indigenous species of organisms. In addition, this thesis will investigate if theNeochetina species that have previously been introduced onto E. crassipes are having any negative effect on this invasive alien aquatic plant.

The introduction of trout has been implicated in the declines in native fish fauna in New Zealand and worldwide. Since the introduction of brown (Salmo trutta) and rainbow (Oncorhynchus mykiss) trout to New Zealand in 1867, their distribution has spread and they have been implicated in the fragmentation of native fish distributions, particularly native non-migratory galaxiids. However, in the Upper Waimakariri basin the co-occurrence of trout and galaxiid populations is relatively common, even in streams where trout reach sizes known to be piscivorous. To investigate mechanisms that may regulate trout and galaxiid co-occurrence, I investigated differences in antipredator behaviour and growth rate between stream types with varying levels of trout presence. Using quantitative survey data collected between 1997 and 2006, I found that trout abundance was low and varied annually in frequently disturbed sites compared their high abundance in stable streams. This finding was used to classify streams into three population types, barrier (trout absent), disturbed (trout presence intermittent) and sympatric (constant trout presence). Using this classification, I tested the effects of trout chemical cues on galaxiid activity and refuge use in artificial channels. There were no differences in activity or refuge use between trout odour and there were no effects of population type or galaxiid size during both the day and the night. Using otolith weight-fish length relationships in galaxiids collected from each population type, I found that galaxiid growth rate was higher in disturbed streams than in stable streams either with or without trout. An experiment manipulating trout size and presence, over two months in a natural stream, found galaxiids from treatments without trout grew slower than those with trout. Slow growth rates in galaxiids above trout-migration barriers and in sympatry, combined with low growth rates in treatments without trout suggest that the mechanisms that regulate galaxiid growth are more complex than previously thought.

I investigated parasitic infection and immunocompetence in populations of introduced bird species in New Zealand (NZ) that had experienced a range of population bottlenecks (11-808 individuals), and compared these parameters to non-bottlenecked conspecifics in the United Kingdom (UK). My aims were two-fold; firstly to assess if population bottlenecks are linked to increased parasite loads and/or decreased immunocompetence, and secondly, to assess at what severity of bottleneck these effects become evident. I found that ectoparasite load (chewing lice, Order: Phthiraptera, Sub-Orders: Amblycera & Ischnocera) was significantly higher in the more severely bottlenecked species in NZ than in the UK, whilst this difference became non-significant at more moderate bottlenecks. The difference was mainly driven by the Sub-Order Amblycera. The prevalence of avian malaria (Plasmodium spp.) was significantly negatively correlated to bottleneck size within NZ, after controlling for body mass. Total leucocyte and differential lymphocyte counts were elevated in the less bottlenecked species that were infected with malaria, whilst the populations at the more severe end of the bottleneck spectrum did not exhibit such a response. Furthermore, heterophil/lymphocyte (HL) ratio (a parameter used as an indicator of environmental and/or immunological stress), was significantly raised in the more bottlenecked species when compared to their UK counterparts, and this difference was correlated with the size of the bottleneck. Immunocompetence was further assessed by the experimental challenge of six introduced birds species in NZ with the mitogen phytohaemagglutinin (PHA). Immune response to PHA was significantly correlated to bottleneck size, but in the opposite direction to that predicted; immune response was greater in the more bottlenecked species. However, this may be an indication of increased investment in immunity, due to increased parasite and pathogen pressure or differential investment in varying components of the immune system. Finally, the immune response to PHA was compared in nestlings of two species that had experienced very different bottlenecks (70 vs. 653). After controlling for ectoparasitic infestation, I found no difference between the two species; however, this finding may be confounded by interspecific competition. Overall, my findings suggest that more severe population bottlenecks may result in increased susceptibility to pathogens, and impact on the immune system. This has a number of implications for the development of conservation protocols, and future avenues of research are suggested.

Determining the past, present and future effects of alien species on native biodiversity is a globally recognized problem. The Wall Lizard, Podarcis muralis, was introduced to Vancouver Island from Europe in 1970. To assess potential competitive interactions with the native Northern Alligator Lizard (Elgaria coerulea), I investigated several aspects of P. muralis ecology. D i h i o n along manmade corridors (e.g. roads and powerlines) and human-facilitated jump dispersal are contributing to range expansion; three separate populations currently exist. Reproductive output of P. muralis was not affected by amount eaten while gravid, but feeding level and incubation temperature affected offspring phenotypes. In comparative tests of locomotor performance, P. muralis was faster than Z. coerulea, but only at moderate temperatures. I found no effect of P. muralis dour on E. coeruela behaviour, but E. coeruela avoided cover objects that housed P. muralis. These two species use similar habitats, but were found on different substrates and mesoslopes. Based on the results of these experiments there is a potential for comvetition between these two lizard species.

No description available.