Non-indigenous species have become a global issue of increasing importance in recent years, with many causing significant environmental and economic damage. Identifying locations vulnerable to invasion allows for focus of management efforts towards prevention of invasions at those locations. In order to determine whether constructed water bodies, such as reservoirs, ornamental lakes or retired mines, are more easily invaded environments than natural water bodies, owing to decreased biotic resistance, the distributions of native and non-indigenous freshwater calanoid copepod species in the North Island were examined. Calanoid copepods in ports and other coastal environments were also examined, in order to determine whether ports are more frequently invaded owing to increased propagule supplies from visiting ships and other sources. The distributions of the native freshwater calanoid copepod species Boeckella hamata, B. propinqua, B. delicata and B. tanea are confined in the North Island of New Zealand to specific technostratigraphic terranes when natural waters only are examined, and as such each species can be considered to have a native range. The recently colonised calanoid copepod species Boeckella minuta (6 locations), Skistodiaptomus pallidus (3 locations) and Sinodiaptomus valkanovi (2 locations) are to date confined to constructed water bodies. Boeckella symmetrica (2 locations) may be confined to constructed water bodies, but the status of one location is unclear. Boeckella triarticulata, a species common in the South Island, is known only from a single farm dam in the North Island. The native species Boeckella hamata, B. propinqua and B. delicata were found to occur in constructed waters, but only B. propinqua was found in constructed water bodies outside their natural ranges (9 locations). Calamoecia lucasi is found in lakes throughout most of the North Island, and is not confined to any one terrane. My results indicate that constructed water bodies are more easily invaded by non-indigenous species than natural water bodies, represents a potential pathway for future invaders to establish, and provides locations for species to spread. In order to determine whether recently established freshwater calanoid copepod species have the potential to spread from their present habitats into other water bodies, the prosomal lengths of non-indigenous calanoid copepod species were measured and compared with those for native species. The results suggest that dietary overlap should prevent the non-indigenous species present to date from spreading into any water bodies with established Boeckella populations, although Sinodiaptomus valkanovi and Boeckella triarticulata could potentially spread to lakes containing only Calamoecia lucasi. Data on the co-occurrences of native freshwater calanoid copepod species support the theory of dietary exclusion, as Boeckella species have not been found to coexist. In order to test whether New Zealand marine environments have been invaded by non-indigenous calanoid copepods, and whether ports have been more regularly invaded than non-port areas, calanoid copepods were sampled from various coastal locations around the North Island. With the possible exception of Sulcanus conflictus, no non-indigenous species were found, indicating that non-indigenous marine calanoid copepod species are not establishing in New Zealand despite a history of invasion elsewhere.

The aim of this Thesis was to improve our understanding and assessment of feeding conditions for zooplanktivorous fish in the Baltic Sea. We investigated (papers I, II) the usefulness of biochemical proxies for assessments of growth and metabolic rates in the dominant Baltic copepod Acartia bifilosa. A predictive model (paper I) for egg production rate (EPR), based on body size, RNA content, and water temperature, was established using females of different geographical origin. This model demonstrates the usefulness of RNA content as a proxy for growth in zooplankton and, together with abundance data, it could be used to evaluate fish feeding conditions. Further (paper II), using A. bifilosa exposed to a food gradient, we evaluated responses of physiological rates and other biochemical proxies for growth and established correlations between physiological and biochemical variables. EPR and ingestion rate were most significantly correlated with RNA content. As assayed variables saturated at different food concentrations, food availability may affect assessments of physiological rates using proxies. In paper III, we explored the effect of high EPR and ingestion rate on astaxanthin content in A. bifilosa. We found that the astaxanthin content decreased at high feeding rates, most likely due to decreased assimilation efficiency. This may impact the quality of zooplankton as prey. The invasion of Cercopagis pengoi, a zooplanktivorous cladoceran, has altered the trophic linkages in the Baltic Sea food web. In paper IV, we evaluated the feeding of zooplanktivorous fish on C. pengoi and found that irrespective of size both herring and sprat feed on it, with large herring being more selective. In turn, C. pengoi feeds mainly on older copepods (paper V), which are acknowledged important in fish nutrition. These results indicate that C. pengoi may compete with fish due to the diet overlap. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In progress. Paper 3: Submitted</p>

No description available.

The native plant communities of Canterbury, South Island, New Zealand have been severely modified and degraded and the Canterbury Plain (750,000 ha) retains few remnants of its original forest and other ecosystems. The research presented here considers the mutualistic roles of exotic and indigenous species in the process of restoring degraded landscapes. Exotic species may have an important role in the (re) establishment of desired indigenous species, and may influence succession through to a forest dominated by them. One aspect of this work describes indigenous plant community regeneration facilitated by exotic willow (Salix spp.) woodland on the Canterbury Plain. Natural colonisation of the willow woodland by native plants was investigated, with respect to variation in the physical environment in the willow stand. Key factors in the success of willow woodland as a nursery for regeneration of native vegetation include: distance to the nearest seed source, the ability to attract seed dispersers (recruitment only occurred under perch sites), flooding potential (higher recruitment in areas less likely to flood) and possibly light availability. Control of vertebrate (and invertebrate) herbivory is also necessary for successful restoration. A second aspect was a field experiment in open pasture and in a non-native remnant woodland which was then used to investigate the effects of shelter, plant spacing, mulching and fertiliser on growth and survival of planted native woody species. With minimal management, the selected mid-late successional plants established poorly in the open pasture and had low survival rates (e.g.,Dacrycarpus dacrydioides, Pseudopanax arboreus, Aristotelia serrata, Melicytus ramiflorus). Only narrow-leaved species (e.g., Plagianthus reg ius, Hoheria angustifolia, Hebe salicifolia, Cordyline australis) survived this open pasture planting. In contrast, most species (broad and narrow-leaved) established under the sheltered sites. Exotic nursery vegetation and the establishment of native species, which will, in time, act as a seed source, will be important in successfully restoring a sustainable indigenous element in the cultural landscape of Canterbury. Ecological restoration requires an integrated approach, identifying and understanding the component processes of regeneration, and of the particular aspects/characteristics of the sites involved. This research shows that naturally established plants where existing shelter is available (in this case established willows) tend to have higher growth rates than individually planted plants in open situations, and that the availability of a suitable seed source can also contribute to successful establishment and growth rates. The meeting of restoration targets on the Canterbury Plain may be accelerated, and costs reduced, through the utilisation of areas where exotic species occur (for instance, extensive willow stands in riparian areas adjacent to waterways) and more particularly, where a local seed source is also available. The findings of this research can contribute to restoration management in helping identify the best practices, based on research, that can lead to the restoration of original plant and animal communities.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The distribution of arboreal and shrub species is related to different environmental conditions. The general goal of this study was to evaluate the influence of environmental factors in structure of communities and dynamics of the natural regeneration in Deciduous Seasonal Forest stretch, located in Quarta Colônia State Park, Agudo, RS, Brazil. The specific goals were to differentiate the structure and floristic of clusters (floristic groups) of the arboreal component, determining which environmental variables influenced the forest structure, identifying what changes have occurred in a year of natural regeneration monitoring and identifing which variables limited or facilitated the establishment of arboreal and shrub populations. Three levels of inclusion were used for sampling forest communities: arboreal component (diameter at breast height (DBH) ≥ 5 cm), sampled in 33 plots of 20 m x 20 m (1.32 ha); natural regeneration Class I (1 cm ≤ DBH < 5 cm), sampled in sub-plots of 4 m x 10 m (0.132 ha); and natural regeneration Class II (DBH < 1 cm and height ≥ 20 cm), sampled in sub-plots of 4 m x 2.5 m (0.033 ha). Cluster II showed the highest average diameter (40.0 cm) and the basal area (1.353 m2 plot-1= 33.825 m2 ha-1). The highest richness (70 species) occurred in Cluster I. The two clusters showed negative exponential diameter distribution, common to the forests with self-regeneration capacity. The species with more developed structure in natural regeneration was Trichilia elegans, Cupania vernalis and Actinostemon concolor, and Trichilia clausseni, Nectandra megapotamica and Allophylus edulis in arboreal component. The species of arboreal component showed association with relief, chemical and textural properties of soil and canopy characteristics, of which only the texture was not related to the regenerating species. The species with the highest value of Natural Regeneration Relative (RNR) kept their posts at the end of the measurements. Different values of Ingrowth Rate (IR), Mortality (MR) and Regeneration (RR); and height growth were detected. For example, the species Myrsine umbellata (TI = 58.3%; TM = 100%) and Annona rugulosa (TM = 37.5%; TM = -37.5%) have excelled in relation to the number of individuals fluctuations, while Baccharis sp. (73.3 cm) and Cabralea canjerana (2.5 cm) showed antagonistic values of height growth. Such changes have been influenced by ecological aspects, light dependence and dispersal strategy, and variables such as thickness (height) of accumulated litter and exposure of relief. The analysis of environmental correlations of the most abundant species indicated, for example, that Actinostemon concolor and Sorocea bonplandii were tolerant to shallow soils, with higher levels of stoniness, recurrent situation in forests of edge of the Southern Plateau, while Cupania vernalis and Nectandra megapotamica were correlated negative with these variables. The different relationships observed show that the use of shrub and tree species in ecological restoration should be based on the analysis of potentially favorable or limiting environmental variables. / A distribuição de espécies arbustivas e arbóreas está relacionada às diferentes condições ambientais. Nesse contexto, o objetivo geral deste estudo foi verificar a influência de fatores ambientais na estrutura de comunidades e na dinâmica da regeneração natural de espécies arbustivas e arbóreas, em um trecho de Floresta Estacional Decidual, localizado no Parque Estadual Quarta Colônia, Agudo - RS. Os objetivos específicos foram: diferenciar a estrutura e a florística de agrupamentos (grupos florísticos) do componente arbóreo; verificar quais variáveis ambientais influenciaram a estrutura da floresta; identificar quais alterações ocorreram em um ano de monitoramento da regeneração natural; identificar quais variáveis atuaram como limitantes ou facilitadoras do estabelecimento de populações arbóreas e arbustivas. As comunidades florestais foram amostradas em três níveis de inclusão: componente arbóreo (diâmetro à altura do peito (DAP) ≥ 5 cm), em 33 parcelas de 20 m x 20 m (1,32 ha); regeneração natural Classe I (1 cm ≤ DAP < 5 cm), em sub-parcelas de 4 m x 10 m (0,132 ha); e regeneração natural Classe II (DAP < 1 cm e altura ≥ 20 cm), em sub-parcelas de 4 m x 2,5 m (0,033 ha). Constatou-se que o Agrupamento II apresentou maiores valores de diâmetro (40,0 cm) e de área basal (33,825 m2/ha), enquanto o Agrupamento I teve maior riqueza (70 espécies). Os dois agrupamentos apresentaram distribuição diamétrica exponencial negativa, indicando que a floresta tem capacidade de autorregeneração. As espécies com estrutura mais desenvolvida na regeneração natural foram Trichilia elegans, Cupania vernalis e Actinostemon concolor e no componente arbóreo foram Trichilia clausseni, Nectandra megapotamica e Allophylus edulis. As espécies do componente arbóreo apresentaram distribuição relacionada ao relevo, propriedades químicas e textura do solo e características do dossel, das quais apenas a textura não teve relação com as espécies regenerantes. As espécies com maior valor de regeneração natural relativa (RNR) mantiveram seus postos ao final das medições. Detectaram-se diferentes valores para as taxas de ingresso (TI), mortalidade (TM) e regeneração (TR), além de incrementos em altura. Por exemplo, as espécies Myrsine umbellata (TI = 58,3%; TM = 100%) e Annona rugulosa (TM= 37,5%; TM = -37,5%) se destacaram em relação às flutuações do número de indivíduos, enquanto Baccharis sp. (73,3 cm) e Cabralea canjerana (2,5 cm) apresentaram valores antagônicos de crescimento em altura. Tais alterações foram influenciadas por aspectos autoecológicos, dependência de luz e estratégia de dispersão, e algumas variáveis como espessura (altura) da serapilheira acumulada e exposição do relevo. A análise de correlações ambientais das espécies mais abundantes indicou que Actinostemon concolor e Sorocea bonplandii foram tolerantes a solos rasos, com maior grau de pedregosidade, situação recorrente nas florestas do rebordo do Planalto Meridional, enquanto Cupania vernalis e Nectandra megapotamica apresentaram correlação negativa com essas variáveis. As diferentes correlações observadas evidenciam que o uso de espécies arbustivas e arbóreas na restauração florestal deve ser baseado na análise de variáveis ambientais, potencialmente favoráveis ou limitantes.

Three of Impatiens species are widespread in the Czech republic, one is native, two of them invasive. Because all species occur in relatively similar habitats, the question is, whether the invasive species can negatively affect the native species, or even the original can can be displaced. The aim of the thesis was: (i) to compare habitat requirments of the Impatiens species, (ii) to determine if the coexistence of species is possible, (iii) to assess the impact of invasive species to the original species. The investigation was carried out using two sets of permanent plots in 5 localities. In the first set with a total of 84 plots (combinations of occurrence of the three species) site characteristics as tree cover, soil humidity, slope and bare land cover were directly measured and nutrient, light, humidity and soil reaction characteristic assessed using Ellenberg indicator values. The second set contained a total of 45 plots with one of the native-invasive congener pair being removed and the intact controls. Number, cover and height of the plants were assesed. The key enviromental factors determining distribution of the species were soil moisture for I. noli-tangere and I. parviflora, and tree cover for I. glandulifera and I. parviflora. Ellenberg indicator values had poor explanation value;...

Text in English / Biodiversity is a fundamental characteristic of life on Earth and encompasses the whole range of variation in living organisms. Lesotho has been subjected to tremendous biodiversity change over the last two centuries, primarily due to socio-economic activities. A number of socio-economic factors have contributed to the loss of biodiversity. However, worldwide experience has shown that, the consequences emanating from loss of biodiversity are sometimes irreversible as some species are threatened by extinction. The study aimed at exploring the impacts of socio-economic activities that result in loss of large game animals, predators and indigenous plants species in Lesotho. To serve this objective, both quantitative and qualitative research methodologies were used to collect data. Quantitative research method was used in pre-post tests whilst qualitative research method was used in interviews and focus group discussions to collect data. The finding and results of the study show that, impacts of human vectors such as immigration, migration, settlement, economic and recreation activities in Lesotho have the impacts to the loss of large game animals, predators and indigenous plants. It is imperative therefore, for Lesotho to find ways to establish more parks and botanic gardens that could offer opportunities for re-introduction of species in Lesotho, thus, adding value to the existing parks. / Environmental Sciences / M. Sc. (Environmental Management)

Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: I evaluated the impact of Prosopis invasion and clearing on ecological structure, function and agricultural productivity in heavily grazed Nama Karoo rangeland on two sheep farms near the town of Beaufort West in the Western Cape Province of South Africa. My aims were to (1) determine the effects of invasion and clearing on rangeland vegetation composition, diversity (alien and indigenous species richness) and structure (alien and indigenous species cover), soil vegetation cover (plant canopy and basal cover) and agricultural productivity (grazing capacity), (2) describe the vegetation processes that underlay the invasion and clearing impacts and (3) evaluate the success of clearing in facilitating unaided restoration of ecological structure, function and agricultural productivity in formerly invaded rangeland. I hypothesised that invasion would significantly change rangeland vegetation composition and structure, leading to greater alien species richness and cover and lower indigenous species richness and cover while clearing would lead to lower alien species diversity and cover and greater indigenous species richness and cover. In addition I hypothesized that invasion would reduce rangeland plant canopy and basal cover and grazing capacity while clearing would substantially increase them. Finally I predicted that vegetation composition, alien and indigenous species cover and richness, plant canopy and basal cover and grazing capacity would revert to pre-invasion status and levels within four to six years of clearing. My results suggest that in heavily grazed Nama Karoo rangeland Prosopis invasion (~15 percent canopy cover) and clearing can significantly change rangeland vegetation composition, with invasion leading to greater alien species cover and lower indigenous species richness, while clearing leads to lower alien species richness and cover and greater indigenous species richness and cover. However invasion seems to have no effect on alien species richness and overall indigenous species cover. Clearing appears to facilitate the spontaneous restoration of alien species cover and indigenous species richness within four to six years but not species composition, alien species richness and indigenous species cover. In addition my results also indicate that Prosopis invasion can lower rangeland plant canopy and basal cover and grazing capacity while clearing, even under heavy grazing, can substantially raise them. Clearing however does not seem to facilitate the restoration of rangeland plant canopy and basal cover and grazing capacity to pre-invasion levels within four to six years after clearing. / AFRIKAANSE OPSOMMING: Ek het die impak van Prosopis indringing en verwydering van indringers op ekologiese struktuur, funksie en landbou produktiwiteit in ‘n swaar beweide Nama Karoo gebied op twee skaapplase naby Beaufort-Wes in die Wes-Kaap provinsie van Suid-Afrika geëvalueer. My doelwitte was om (1) te bepaal wat die gevolge van die indringing en verwydering van indringers op die natuurlike plantegroei samestelling, diversiteit (uitheemse en inheemse spesiesrykheid) en struktuur (uitheemse en inheemse spesies bedekking) sal wees, sowel as die effek op plantegroei bedekking (kroon en basalebedekking) en landbou produktiwiteit (weidingkapasiteit), (2) die plantegroei prosesse te beskryf wat onderliggend deur die impakte van indringing en verwydering van indringers veroorsaak word, en (3) die sukses van die verwydering van indringers te evalueer deur die fasilitering van blote restorasie van ekologiese struktuur en funksie en landbou produktiwiteit in voorheen ingedringde gebiede. My hipotese is dat indringing ‘n aansienlike verandering in natuurlike plantegroeisamestelling en struktuur sal veroorsaak, wat sal lei tot groter uitheemse spesiesrykheid en bedekking met minder inheemse spesiesrykheid en bedekking, terwyl die verwydering van indringers sou lei tot minder uitheemse spesie diversiteit en bedekking met 'n groter inheemse spesiesrykheid en bedekking. Verder vermoed ek dat indringing die natuurlike kroon- en basalebedekking en weidingkapasiteit sal verminder, terwyl die verwydering van indringers dit aansienlik sal verhoog. Ten slotte voorspel ek dat plantegroei samestelling, uitheemse en inheemse spesiesbedekking en -rykheid, kroon- en basalebedekking en weidingkapasiteit sou terugkeer na voor-indringing status en vlakke binne vier tot ses jaar na die verwydering van indringers. My resultate daarop dat die indringing van Prosopis (~ 15 persent kroonbedekking) en die verwydering van indringers in swaar beweide Nama Karoo gebiede ‘n aansienlike verandering in die gebied se natuurlike plantegroei samestelling toon, waar indringing gelei het tot groter uitheemse spesiesbedekking en minder inheemse spesiesrykheid, terwyl die verwydering van indringers lei tot minder uitheemse spesiesrykheid en groter inheemse spesiesrykheid en - bedekking. Dit lyk egter of indringing geen effek op uitheemse spesiesrykheid en algehele inheemse spesiesbedekking het nie. Die verwydering van indringers blyk om die spontane herstel van indringerbedekking en inheemse spesiesrykheid binne vier tot ses jaar te fasiliteer, maar nie spesiesamestelling, uitheemse spesiesrykheid of inheemse spesiesbedekking nie. Benewens dui my resultate ook aan dat Prosopis indringing die natuurlike kroon- en basalebedekking sowel as weidingskapasiteit verlaag, terwyl die verwydering van indringers, selfs onder swaar beweiding, die bedekking aansienlik kan verhoog. Verwydering van indringers lyk egter nie asof dit die herstel van die gebied se natuurlike kroon- en basalebedekking en weidingkapasiteit na voor-indringing vlakke toe kan fasiliteer binne vier tot ses jaar na die verwydering van indringers nie.

The spread of exotic species is considered to be one of the most significant threats to ecosystems and emphasises the need for appropriate management interventions. The majority of marine non-indigenous species (NIS) are believed to have been introduced via ship biofouling and their domestic spread continues to take place via this mechanism. In some countries, biosecurity systems have been developed to prevent the introduction of NIS through biofouling. However, implementing biosecurity strategies is difficult due to the challenges around identifying high-risk vectors. Reliable predictors of risk have remained elusive, in part due to a lack of scientific knowledge. Nonetheless, invasion ecology is an active scientific field that aims to build this knowledge. Propagule pressure is of particular interest in invasion ecology as it describes the quantity and quality of the propagules introduced into a recipient region and is considered to be an important determinant in the successful establishment of NIS. Environmental history affects health and reproductive output of an organism and, therefore, it is beneficial to examine this experimentally in the context of biofouling and propagule pressure. The aim of this thesis was to examine how voyage characteristics influence biofouling recruitment, survivorship, growth, reproduction and offspring performance through the ship invasion pathway. This was to provide fundamental knowledge to assist managers with identifying high-risk vessels that are likely to facilitate the introduction or domestic spread of NIS, and to understand the processes affecting biofouling organisms during long-distance dispersal events. Chapter One provides an introduction to the issues addressed in this thesis. Each data chapter (Chapters Two – Five) then focused on a stage of the invasion process and included field experiments using a model organism, Bugula neritina. Finally, Chapter Six provides a summary of key findings, discussion and the implications to biosecurity management. Throughout this thesis, the effect of donor port residency period on the success of recruits was highlighted. Chapter Two focused on recruitment in the donor region. As expected, recruitment increased with residency period. Importantly, recruitment occurred every day on vulnerable surfaces, therefore, periods as short as only a few days are able to entrain recruits to a vessel hull. The study presented in Chapter Three showed that there was high survivorship of B. neritina recruits during 12 translocation scenarios tested. In particular, the juvenile short-residency recruits (1-8 days) survived voyages of 8 days at a speed of 18 knots; the longest and fastest voyage simulated. Interestingly, variation in voyage speed and voyage duration had no effect on the survivorship of recruits, but did have legacy effects on post-voyage growth. Again, B. neritina which recruited over very short residency periods of 1 day continued to perform well after translocation and had the highest level of reproductive output after the voyage scenarios (Chapter Four). Recruits that were older (32-days) and reproductively mature at the commencement of the scenarios failed to release any propagules. Even though the number of ‘at sea’ and ‘port residency’ days were equal, reproductive output was higher after short and frequent voyages than after long and infrequent voyages. Finally, the study presented in Chapter Five examined transgenerational effects of B. nertina. Results showed that although the environmental history of the parent colony had a carry-over effect on offspring performance, it was the offspring environment that was a stronger determinant of success (measured by reproductive output and growth). Although cross-vector spread is possible (i.e. parent and offspring both fouling an active vessel), offspring released from a hull fouling parent into a recipient environment will perform better. In combination, these studies have provided new insights into NIS transport via vessel biofouling. Although shipping pathways are dynamic and complex, these results suggest that juvenile stages that recruit over short residency periods and are then translocated on short voyages, may pose a higher risk for NIS introduction than originally assumed. This has implications for marine biosecurity management as short residency periods are common and short, frequent voyages are typical of domestic vessel movements which are largely unmanaged.

Text in English / Biodiversity is a fundamental characteristic of life on Earth and encompasses the whole range of variation in living organisms. Lesotho has been subjected to tremendous biodiversity change over the last two centuries, primarily due to socio-economic activities. A number of socio-economic factors have contributed to the loss of biodiversity. However, worldwide experience has shown that, the consequences emanating from loss of biodiversity are sometimes irreversible as some species are threatened by extinction. The study aimed at exploring the impacts of socio-economic activities that result in loss of large game animals, predators and indigenous plants species in Lesotho. To serve this objective, both quantitative and qualitative research methodologies were used to collect data. Quantitative research method was used in pre-post tests whilst qualitative research method was used in interviews and focus group discussions to collect data. The finding and results of the study show that, impacts of human vectors such as immigration, migration, settlement, economic and recreation activities in Lesotho have the impacts to the loss of large game animals, predators and indigenous plants. It is imperative therefore, for Lesotho to find ways to establish more parks and botanic gardens that could offer opportunities for re-introduction of species in Lesotho, thus, adding value to the existing parks. / Environmental Sciences / M. Sc. (Environmental Management)