Pollination is an essential ecosystem service, increasing reproductive success of many crops, which can be provided by managed pollinators, wild bees (including honeybees) and other insect pollinators. However, the pollination services and the economic value of wild pollinators are often underestimated. Better understanding of the factors that influence honeybee foraging behaviour and pollination efficiency can contribute to the improvement of management practices that aim to enhance crop pollination and ecosystem services. The objectives of this study were to investigate the importance of managed honeybees and wild honeybees to sunflower pollination as well as to evaluate the response of honeybees to different levels of floral rewards and to behavioural interactions with wild flower visitors. The study was conducted in 16 commercial sunflower farms and one experimental farm of South Africa during the 2009 sunflower flowering season. The results showed that insects, particularly honeybees, were efficient pollinators, improving sunflower production in all self-fertile sunflower cultivars used in this study. Furthermore, wild honeybee colonies were found to be as efficient as managed honeybee colonies in sunflower pollination near to natural habitat. Both sunflower yield and the abundance of pollinators decreased with distance from natural habitat, suggesting that sunflower yield is directly correlated with the abundance of pollinators. The amount of nectar present in the florets of sunflower significantly affected pollinator behaviour, influencing honeybee visitation length and foraging rate which prefer to exploit floral rewards from the same source if they find the higher amount per foraging trip, possibly having a negative impact on cross-pollination. Moreover, the concentration of nectar collected from honeybees was significantly lower than the nectar concentration from florets, suggesting that honeybees diluted highly concentrated sunflower nectar with their saliva to their optimum concentration level. Interspecific exploitative competition between honeybees and wild pollinators (wild bees, butterflies and moths) significantly increased the movement of honeybees among sunflower heads, which enhances cross-pollination. Furthermore, behavioural interactions influenced the length of foraging time spent by individual honeybees per sunflower head. Butterflies were the most influential in enhancing honeybee foraging movement, followed by wild bees and then moths. The importance of a given flower visitor species to honeybee movement is likely related to the size of the visitor, as the bigger size of butterflies and movement of their wings increases the chance of disturbing a neighbouring honeybee. Conservation of natural habitat is important to maintain the diversity of flower visitors which indirectly contribute to crop production by enhancing honeybee foraging activity and consequent direct pollination service. Furthermore, the pollination effectiveness of wild pollinators, density of wild honeybees surrounding sunflower fields and effects of human activities on pollination disruption are suggested as topics for future research. / Dissertation (MScAgric)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted

Marine unconsolidated sediments constitute the largest ecosystems on earth in terms of spatial coverage, but there are still critical gaps in the science required to support conservation and ecosystem-based management. This is mainly due to the inaccessibility of these ecosystems in wave-exposed environments or deeper waters and the difficulty in observing biota in their three-dimensional sedimentary habitat. Currently, the physical driving processes of intertidal unconsolidated sediment ecosystems are much better understood than those of the subtidal ecosystems. However, these ecosystems are linked through water and sediment movement. This thesis, therefore, considers the continuum of unconsolidated sediment ecosystems across the entire continental shelf (i.e. intertidal to the shelf edge). The aim of this thesis was two-fold; (i) to advance the foundational understanding of biodiversity patterns and driving processes in unconsolidated sediment habitats, and (ii) to apply this knowledge in the development of a systematic conservation plan for marine unconsolidated sediment ecosystems. The South African west coast continental shelf was used as a case study in order to represent Eastern boundary upwelling regions. This study sought to investigate biodiversity patterns in macro-infaunal communities and determine their driving processes for incorporation into habitat classifications and the development of a habitat map. Systematic conservation plans require a map of biodiversity patterns and processes, and quantitative conservation targets to ensure representation of all biodiversity features including habitats.in marine protected areas. This thesis provided these key elements by classifying the unconsolidated sediment habitats and determining habitat-specific evidence-based conservation targets to support conservation of these important ecosystems. The application of these elements was then demonstrated in a systematic conservation plan for the unconsolidated sediment ecosystems of the South African west coast. Diversity patterns were examined using physical and macro-infauna data, ranging from the beach to the shelf edge (0-412 m). These data were analysed to develop two different habitat classifications, namely seascapes derived from geophysical and biophysical data, and biotopes derived from the combination of macro-infaunal and physical data. Multivariate analyses of 13 physical variables identified eight seascapes for the unconsolidated sediment samples from 48 sites on the South African west coast. These were based on depth, slope, sediment type, and upwelling-related processes (i.e. maximum chlorophyll concentration, sediment organic carbon content and austral summer bottom oxygen concentration). Latitude and bottom temperature were not considered major drivers of seascapes on the west coast because latitude closely reflected changes in upwelling-related processes and the temperature range was narrow across the shelf. This study revealed that productivity, a biophysical variable not usually included in geo-physical habitat classifications, played a significant role in the definition of seascapes on the South African west coast. It is therefore recommended that productivity be included in future seascape classifications to improve the utility of these classifications particularly in areas of variable productivity. Seascapes should, however, be tested against biological data to improve the understanding of key physical drivers of communities in unconsolidated sediment ecosystems. Macro-infaunal community distributions were determined along with their physical drivers for the unconsolidated sediments of the South African west coast. A total of 44 828 individuals from 469 taxa were identified from 48 sites representing 46.2 m2 of seafloor. Seven distinct macro-infaunal communities were defined through multivariate analyses and their key characteristic and distinguishing species were identified. These communities reflected five depth zones across the shelf, namely beach, inner shelf (10-42 m), middle shelf (60-142 m), outer shelf (150-357 m) and shelf edge (348-412 m). The processes driving the community structure of these depth zones were postulated to be tides, wave turbulence, seasonal hypoxia, habitat stability and homogeneity, and internal tides and/or shelf break upwelling, with drivers listed in order of increasing influence with depth. The middle shelf was further separated into three distinct communities based on sediment type, sediment organic carbon content and frequency of hypoxia. Variations in water turbulence, sediment grain size, upwelling-related variables and riverine sediment input were identified as the likely primary drivers of macro-infaunal community patterns. This chapter culminated in the development of a biotope classification based on the combination of macro-infaunal communities and their physical habitats (i.e. biotopes). South Africa has developed an expert-derived National Marine and Coastal Habitat (SANMC) Classification System which is used as a biodiversity surrogate in ecosystem assessment and spatial planning. This thesis tested the validity of this classification and the data derived Seascape classification against macro-infauna species abundance and biomass data in an effort to determine how well the different classifications represent macro-infaunal diversity of the west coast. These two classifications were also compared to the Biotope classification which combines macro-infaunal communities with their physical habitats. A canonical analysis of principle coordinates (CAP) was utilised to test the success with which each sample was allocated to the relevant habitat type in each classification. The total allocation success for each classification was used as a measure of effectiveness in terms of representing biodiversity patterns. Both classifications had similar allocation successes of 89-92 percent and 92-94 percent for the Seascape and National Habitat Classification respectively, but either over- or under-classified the macrofauna communities. The Biotope classification had the highest allocation success (98 percent), therefore it is the most accurate reflection of the macrofauna biodiversity patterns on the west coast. A key finding of this study was the increasing accuracy of classifications from physically- to expert- to biologically-derived habitat classifications. In this thesis, the Biotope classification was deemed the best representative of biodiversity patterns and was therefore used to produce the Biotope map for use in spatial assessment and planning. The distinct depth patterns that emerged in both the Seascape and Biotope classifications highlighted the need for further investigation of the relationship between depth and biodiversity. Despite variability in macro-infaunal communities, a general unifying pattern in biodiversity across the shelf was sought. Three relationships between depth and species richness have been described in the literature; namely a unimodal pattern, a positively linear relationship with depth, and no relationship between depth and species richness. These hypotheses were tested on the west coast. Two different species richness metrics were utilised to test the depth-diversity relationship, namely observed species density (spp.0.2m-2) and estimated species richness (spp.site-1). Observed species density increased from the beach to the shelf edge (350 m), then decreased to 412 m. The decline may have been due to difficulty in detecting species at greater depths as a result of sampling challenges. The inclusion of an innovative extrapolative method for estimating species richness (the capture-recapture heterogeneity model) within the Bayesian statistical framework mitigated the effects of species detection heterogeneity and revealed that species richness actually increased continuously across the shelf from beach to shelf edge. Thus the general relationship between depth and species richness is positively linear on the west coast of South Africa The new macro-infauna dataset and biotope map provided the opportunity to develop the first habitat-specific evidence-based conservation targets for unconsolidated sediments of the west coast. Species-Area Relationship (SAR) based conservation targets were developed for the biotopes using a modification of the generally accepted methodology. The accepted methodology has three steps (i) the estimation of total species richness for each habitat using the Bootstrap asymptotic estimator, (ii) the calculation of the slope of the species area curve (i.e. the z-value), and (iii) the calculation of targets representing 80 percent of the species. The inclusion of an innovative extrapolative species richness estimator, the Multi-species Site Occupancy Model (MSOM) provided better species richness estimation than the more conventional bootstrap species richness estimator, even though both are based on species accumulation. The MSOM, applied in the Bayesian statistical framework takes detectability of a species into account.

Earth's species are disappearing at a rate unprecedented in human history, yet whether this loss will make the ecosystem "services" that support our civilisation more vulnerable to environmental change is poorly understood. This thesis investigates two different aspects of land surface modelling. It firstly models the role of biodiversity in ecosystem resilience using the Lotka-Volterra and single resource models to model diversity using competition coeffcients, stochastic noise and evolution inspired trait diffusion and then examines if higher diversity makes these simple models more resistant to temperature increases. It secondly develops a theoretical plant demography model, based on the continuity equation, to robustly represent forest size diversity. This avoids both the complexity and maintainability issues seen in Forest Gap models and improves the representation of land use and land cover change and of regrowth time-scales after disturbance, which can be unrealistic in some of the previous generation of Dynamic Global Vegetation Models (DGVMs), such as TRIFFID (Cox et al., 2001). While the Lotka-Volterra with competition coeffcients and the single resource with stochastic noise approaches are found to be impractical, the single resource model with trait diffusion successfully shows that higher diversity requires a faster critical rate of temperature change before system net primary productivity (NPP) collapses. The continuity equation model of vegetation demography is solved analytically with the size dependence of the growth rate approximated first by a power law and then with a quadratic. The power law solution can be reduced to a "self-thinning" trajectory, and the quadratic solution gives either a rotated sigmoid or 'U-shape' distribution of plant sizes, depending on the ratio of mortality to maximum growth gradient. The model is then extended to produce the basis of a new Dynamic Global Vegetation Model (DGVM) called "Robust Ecosystem Demography" (RED), adapting the plant physiology from TRIFFID DGVM to generate a size-dependent growth function. A proportion of the NPP from this growth is used for reproduction and the shading is modelled simply by random overlap. The model is found to better represent regrowth time-scales compared to TRIFFID and is also found to demonstrate an optimum proportion of NPP to reproduction which decreases with plant lifetime.

Oomycetes are eukaryotic fungus-like microorganisms that are known to be pathogenic to plants and animals, causing both ecological and economic damage. Animal pathogenic oomycetes, such as Saprolegnia species are destructive pathogens to many aquatic organisms and are found in most parts of the world. Phytophthora species cause a number of plant diseases. Pythium are less understood as many of these species are saprotrophs which are not thought to be pathogenic. Oomycete research has focussed mainly towards the characterisation and control of pathogenic species with very little information on the ecology of Oomycetes. In this thesis, oomycete species were isolated from water samples collected from rivers in Scotland and Northern England. Baiting and water filtration were used to compare the reliability of both methods, and nested PCR was used to compare the number and types of species obtained in comparison to conventional culturing methodologies. The results suggest that water filtration provided a fast, reliable method for isolating abundant, hardier species such as Pythium undulatum, Saprolegnia diclina, Saprolegnia delica, and Saprolegnia ferax. Water chemistry, surrounding land use, seasonality and land elevation were found to be important factors in Oomycete diversity. Nested PCR of oomycetes directly from filters to obtain target DNA from organisms which are more difficult to culture or less numerous proved to be useful for some species, but will need more refinement of primer and methodologies to obtain species of interest. Sampling of the rivers resulted in the isolation of three new Pythium spp. isolated from the Rivers Spey and Dochart in Scotland. Phylogenetic analysis, infection studies, growth rates and microscopy were used to characterise these three species.

The queen conch, Lobatus gigas, is key to the Bahamian way of life. Recent studies suggest that commercial stocks will be depleted in The Bahamas in 10-15 years. In response to this, an egg farm was established in a historic breeding ground in Moriah Harbour Cay National Park, Exuma, Bahamas. Previously used for aquaculture, the egg farm concept was tested as a restoration method. Conch were tagged (n=251) and stocked in a 1,385 m2 (0.14 ha) circular enclosure at an equivalent density of 1,813/ha or 1 conch/5.5 m2. The egg farm was visited every 24-48 hours during the study period (May 26-August 14, 2019) to examine conch distribution, burial, predation, breeding, and egg mass laying. Queen conch Essential Fish Habitat was characterized in this study, contributing to a knowledge gap concerning conch spawning areas. No egg masses were laid, despite temperature, sediment solid-phase organics, calcium carbonate, and other seagrass habitat characteristics displaying similarities to previous studies in which conch spawned. It is speculated that egg laying did not occur due to handling disturbances, which may have caused the conch to resorb their gonads. Comprehensive recommendations are made for future egg farms intended for restoration. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21823号 / 農博第2336号 / 新制||農||1067(附属図書館) / 学位論文||H31||N5195(農学部図書室) / 京都大学大学院農学研究科生物資源経済学専攻 / (主査)教授 栗山 浩一, 教授 伊藤 順一, 教授 梅津 千恵子 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22710号 / 地環博第200号 / 新制||地環||39(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 星野 敏, 教授 西前 出, 教授 寶 馨 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

Unicellular, eukaryotic organisms - known as protists - form the base of all aquatic food webs. Frequently, marine protists are divided into either phytoplankton or (proto)zooplankton. Phytoplankton use phototrophy to acquire their energy from light to fix carbon dioxide into organic carbon, while protozooplankton use phagotrophy to directly acquire organic carbon from their prey. Mixoplankton that employ mixotrophy, i.e. the combination of phototrophy and phagotrophy within one cell, are often neglected. However, many marine protists are mixoplankton and they are ubiquitous in the worlds’ oceans. In oligotrophic oceans, mixoplankton are the base of food webs and many harmful algal blooms are formed by mixoplankton. Yet, the concept of mixoplankton is slow to mature within coastal water management. This thesis hypothesizes that the whole protist community, including mixoplankton, needs to be taken into account to understand and predict the effect of anthropogenic pressures on coastal systems. This thesis is a cumulative summary of three papers that employ data analysis, model developments and modelling scenarios to test this hypothesis. As a study area the Southern North Sea was chosen as it is an exceptionally well sampled coastal sea that is forecast to be heavily modified in the future. In a first step, routine monitoring data from the Southern North Sea were analyzed. The data analysis showed that the relative occurrence of mixoplankton was highest in seasonally stratified, clear, dissolved inorganic nutrient depleted environments. In a second step, a mathematical model, called PROTIST, was developed with the aim to reproduce the trophic composition of protist communities across abiotic gradients. Not only was PROTIST capable of reproducing the trophic composition of protist communities in the Southern North Sea, a sensitivity analysis conducted on the model results also showed that the occurrence of mixoplankton in the Southern North Sea is driven mainly by the availability of dissolved inorganic phosphate and silica and not by the availability of light. In a third step, PROTIST was used in a 3D model scenario of the North Sea to research whether the planned intensification of seaweed aquaculture affects the composition of protist communities. Preliminary 3Dmodel results show that seaweed aquaculture in the Southern North Sea could decrease nutrient concentrations in winter and lead to an increase in mixoplankton biomass. Pooling the information gained from the different approaches, this thesis concludes that coastal zone management should take mixoplankton into account to understand and predict the effect of future anthropogenic pressures on coastalecosystems. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

The lack of cultural and economic recognition of the significance of wetlands arguably led to theirdevastating and rapid loss compared to other ecosystems. To reverse this trend and establish a reasonablevaluation of wetlands, the foundations of socio-ecological concepts were laid in late 20th century thatsuggested the acknowledgement of the functions, values, and services of ecosystems. Subsequently, inthe 21st century the scientific interest in wetland functionality is driven beyond mere conservationalefforts and includes the appropriation of their values for sustainable development, and the utilization oftheir functions as nature-based solutions to humanity’s growing environmental problems. In light of thistrend, this literature review outlines the most critical functions of Swedish wetlands and places them intheir contexts of significance. A meta-analysis of the scientific literature on Swedish wetlandswas conducted with the assessment of wetland functions, wetland types, and the drivers that motivatedeach study. To identify the most critical functions and their contexts, patterns and trends wereinvestigated among these categories. Results show that the most recognised functions of Swedishwetlands are their nutrient-pollutant retention, ecosystem maintenance, and carbon sink functions.Their connections to distinct drivers suggest that their values mainly lie in their potential tomitigate negative impacts of anthropogenic activities, such as eutrophication and global warming,and to support local and regional biodiversity. Synergies among these functions are alsodiscussed, as exemplified by dual-purpose constructed wetlands. Moreover, understudiedhydrological functions are thought to reflect their undervaluation and indicate possible risksattached to associated knowledge gaps. By summarising and contextualising the most importantfunctions, this literature review sheds light on the contemporary understanding and valuation ofwetland functions in Sweden. It is suggested that these novel perceptions effectively drive wetlandconstruction and restoration, the ever-more popular strategies to mitigate climate- and industryrelated risks. Consequently, the recognition, interpretation, and application of wetland functionswill all contribute to the future landscape composition of Sweden.