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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Stream Insect Production as a Function of Alkalinity and Detritus Processing

Osborn, Thomas G. 01 May 1981 (has links)
The study was conducted to determine if aquatic insect production was significantly different between high and low alkalinity mountain streams and if any differences were associated with food availability factors. The major objectives included determining: (1) if annual production differences occur between high and low alkalinity streams; (2) if processing rates of terrestrial detritus differs between high and low alkalinity streams; (3) if detrital processing rates are related to stream insect productivities; (4) if primary productivity varies between high and low alkalinity streams; (5) if toxic effects or micronutrient limitations exist in high or low alkalinity streams that could limit insect survivals. A high alkalinity stream was defined as one having over 150 milligrams per liter average total alkalinity. Six study sites on four high alkalinity streams were located in the Wasatch National Forest near Logan in northern Utah. Six study sites on four low alkalinity streams were located in the Shoshone National Forest near Yellowstone National Park in northern Wyoming. Sites from each region were shown to not differ significantly for all physical parameters tested. The mean annual production of 22 of the 29 invertebrate taxa analyzed were significantly higher in the high alkalinity streams, while 2 taxa were significantly more productive in the low alkalinity streams. The mean annual production of all taxa summed was significantly higher in the high alkalinity streams. All high alkalinity sites had significantly higher production than any low alkalinity site. Alder leaf packs left open to allow invertebrate activity had a significantly higher rate of weight loss in the high alkalinity stream. Alder leaf packs placed inside fine mesh bags to exclude invertebrate activity showed no significant differences in weight loss when the experiments were terminated. The patterns of weight loss for these mesh packs did differ between the two stream types. In the high alkalinity stream, the leaves had a early rapid weight loss phase followed by a period of reduced weight loss. In the low alkalinity stream, the leaves experienced little weight loss during the early phase of the study but lost weight rapidly during the latter phase. The survivorships of all taxa tested did not differ significantly between high and low alkalinity water. Estimates of detrital inputs based on drift measurements and standing crops of detritus collected with invertebrate samples showed no significant differences between regions. The following conclusions resulted from the study. The high alkalinity streams had a significantly much higher production of aquatic invertebrates than did the low alkalinity streams. The high alkalinity streams also had significantly higher standing crops of attached algae and faster processing of alder leaves. Algae and processed allochthonous detritus are two major food sources for many aquatic invertebrates. It is concluded that a major reason for the great difference in invertebrate production between the physically similar high and low alkalinity streams in this study was the availability difference of these two food sources. The insects in the high alkalinity streams had much more of both food types available to them so a much higher annal production of aquatic invertebrates was supported.
12

Detrital Production in Kelp Beds

Krumhansl, Kira 28 February 2012 (has links)
Detrital subsidy from highly productive kelp beds and forests to adjacent habitats represents a major form of connectivity between coastal ecosystems that regulates regional patterns of community organization and production. In this thesis, I investigated environmental and biological factors that influence the rate of detrital production in Nova Scotian kelp beds, with emphasis on the role of invasive species in altering these dynamics. The rate of blade erosion of the dominant kelp species (Saccharina latissima and Laminaria digitata) increased significantly with the level of encrustation by the invasive bryozoan Membranipora membranacea and the extent of grazing damage by the native snail Lacuna vincta, and by increased water temperature and site exposure. The rate of detrital production (as dry mass) ranged from 0.5 to 1.71 kg m-2 y-1 across 5 sites, and increased linearly with kelp bed biomass. Spatial variation in the total level of grazing damage on kelp blades by L. vincta was explained in part by a negative relationship with site exposure, and the distribution of grazing along blades was regulated by kelp growth rate and the associated production of grazing-deterrent polyphenolics. Grazing damage by L. vincta that exceeded 0.5 to 1.0% of blade area caused increased rates of erosion during heavy wave action associated with a passing hurricane. The maximum stress before breakage, toughness, and extensibility of blade tissues decreased with the degree of encrustation by M. membranacea or grazing damage by L. vincta, which cause degradation and removal of the outer cell layers of kelp tissues, resulting in stress concentration and breakage at lower force applications than required to break undamaged tissues. The invasive green alga Codium fragile and S. latissima differed with respect to nutritional quality and changes in biochemical composition that occurred over the course of degradation on a sandy bottom adjacent to a kelp bed. Macrofaunal communities colonizing detrital deposits responded to these differences. These findings demonstrate that invasive species can alter the quantity and quality of detritus produced from subtidal kelp beds, and that their community-level effects can extend well beyond the invaded habitats via the export of detritus.
13

Investigating the ecological implications of wrack removal on South Australian sandy beaches

Duong, Huynh Lien Stephanie, stephanie.duong@flinders.edu.au January 2008 (has links)
Accumulations of seagrass, macroalgae and other matter, collectively known as wrack, commonly occur on many sandy beaches, and can play an important role in coastal and nearshore ecosystems. Despite this, wrack removal from sandy beaches is a widespread and increasingly common practice globally, and there is little information regarding the ecological effects of such wrack removal on sandy beaches. The aim of this thesis was to establish the ecological importance of wrack in South Australian (SA) sandy-beach ecosystems. As a first step in furthering our understanding of the effects of wrack removal, I aimed to assess the importance of wrack, independent of the effects of wrack removal. The second over-riding aim of this thesis was to assess the ecological effects of wrack removal on aspects of these systems. To date, the methods used for quantifying the size of wrack deposits on sandy beaches have had limited use due to the time and expertise required to conduct thorough sampling. In Chapter 2, I thus tested the accuracy of a rapid “photopoint” method to visually estimate percentage wrack cover as well as provide an archived record. Comparisons of results obtained from conventional transects with those from photopoints indicated that the photopoint technique can be used to rapidly and accurately estimate % wrack cover on sandy beaches. The photopoint method has a wide range of potential applications and represents a valuable advance in the field. Currently our knowledge of the amounts and types of wrack on SA shores is limited, despite these accumulations being a feature of some SA beaches. Wrack deposits in three biogeographical regions of SA were thus repeatedly surveyed to assess spatial (between and within regions) and temporal (seasonal and inter-annual) variation (Chapter 2). Both wrack cover and the composition of wrack deposits varied spatially and temporally. Wrack deposits contained a diverse array of seagrass, algal, other biotic materials and anthropogenic debris. The South East region of SA had distinctly-different wrack deposits compared to the Metropolitan and Fleurieu Peninsula regions; in general, the cover of wrack was higher, and the diversity and biomass of kelps, red algae and green algae was higher in this region compared to the other two regions. South Australian wrack deposits are thus dynamic and complex. The amount of wrack deposited and retained on a beach may be affected by the beach morphology but, to date, few studies have investigated this link. I assessed wrack cover on beaches with a range of morphodynamic types and found that beaches that were more dissipative in nature had a greater cover of wrack than beaches of the reflective type. I also examined whether wrack deposits affected the sediment characteristics of underlying and nearby sediments. Wrack deposits had little measurable effect on underlying sediments and did not affect particle-size distribution or organic-matter content. There was, however, a trend for beaches in the South East region of SA to have higher organic matter content in their sediments, and these beaches also have higher wrack cover and higher proportions of algae in their deposits. There was also a trend for beaches with higher wrack cover to have less compacted sediments, although this trend was not consistent. Overnight pit-fall trapping surveys of the macrofauna on four SA sandy beaches indicated that local macrofaunal communities were diverse (representing 72 species from 19 Orders in total), abundant, and variable in both time and space. The macrofauna encountered were mostly terrestrial taxa with only 2 truly marine species, and spanned multiple trophic levels, concurring with the results of previous studies. Macrofaunal abundances were higher where associated with wrack than in bare sand, and macrofaunal communities differed between the driftline of wrack and wrack patches away from the driftline. Within the driftline itself, there were few differences between bare sand and wrack-covered areas, suggesting that the entire driftline area is important as a habitat and food resource. Thus, wrack deposits provide an important habitat and food source for macrofauna, and the driftline provides an area of beach with concentrated resources, which in turn concentrates a distinct macrofaunal community. Wrack deposition on sandy beaches varies spatially and is affected by morphological features on the beach-face such as cusps. In Chapter 5, I thus tested a series of hypotheses regarding the differences in wrack deposits, sediments and macrofaunal communities between cusp bays and horns. Bays had greater cover and larger pieces of wrack than horns. Sediment organic-matter content was greater on horns than in bays but mean particle size did not differ consistently between bays and horns. Macrofaunal diversity was higher in bays and this pattern was probably driven by differences in the cover of wrack between bays and horns. Cusp morphology thus influences the distribution of wrack on the beach-face, which in turn influences the distribution of macrofauna. Studies of sandy beaches with cusps should therefore be explicitly designed to sample cusp features and their associated wrack deposits. Chapter 6 assesses the incorporation of wrack into beach and nearshore ecosystems via two pathways: decomposition and incorporation into trophic webs. I assessed the decomposition of algal and seagrass wrack using litterbag experiments and found that after a very rapid initial loss of mass, likely due to cell lysis and leaching, the rate of decomposition of wrack was much slower. Most release of nutrients from organic matter decay thus appears to occur in the first few days after deposition and the processes affecting the rate and nature of wrack decomposition vary among taxa (i.e. algal versus seagrass and among species). Stable isotopes of C and N were used to assess whether beach macrofauna or nearshore macro-invertebrates and fish might rely on wrack as a source of nutrition. I found that seagrasses did not provide a food source for any consumers but algae, particularly brown algae including kelps, appeared to be potential sources of nutrition for beach and nearshore consumers. The incorporation of wrack into beach and nearshore ecosystems may thus occur primarily through consumption of algal wrack by herbivores such as amphipods and dipterans, with predation on them being important pathways for the transfer of nutrients and energy into higher trophic levels. The amount of wrack in the surf zone did not affect the abundance and species richness of fish and invertebrates netted there. The aim of Chapter 7 was to determine the effects of wrack removal on sandy beach macrofaunal communities. In the first study the effects of large-scale commercial harvest of wrack on the macrofaunal communities at Kingston were assessed. The macrofaunal communities present in the ‘Natural’ area of Kingston beach were far more diverse and abundant, and included different species, compared to the ‘Cleared’ area at Kingston. In the second part of Chapter 7, I experimentally removed wrack from the driftline of beaches to assess short-term effects on macrofaunal communities. The experimental treatment did not appear to have any measurable effects on the macrofaunal communities. I also analysed material that was removed from the beach in the raking experiments and found that a large proportion of the material (e.g. 81% of the DW) was sand. I recommend that future studies into the effects of wrack removal use large cleared areas of beach, attempt to use the same wrack removal methods and/or machinery used locally, and assess the macrofaunal communities repeatedly and over longer times following wrack removal activities. In Chapter 8, I attempt to assess the effects of removal of wrack for beach ‘cleaning’ or commercial ‘harvest’ of wrack by comparing key indicators from Chapters 2 to 7. Implications and recommendations for the management of wrack are discussed, including with regard to the techniques used in this thesis and their applicability in managing wrack deposits. I attempt to identify the shortcomings of this research as well as directions for further research. Thus I have demonstrated that wrack in SA provides an important link between offshore habitat and nearshore, beach and terrestrial habitats via the transfer of organic matter and nutrients. Wrack interacts with beach morphology and sediments, provides habitat for macrofauna, remineralises nutrients through its decomposition, and provides the basis of a complex trophic web. I conclude that wrack is a key component in beach ecosystems.
14

An analysis of the seasonal and short-term variation of road pavement skid resistance

Wilson, Douglas James January 2006 (has links)
It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.
15

An analysis of the seasonal and short-term variation of road pavement skid resistance

Wilson, Douglas James January 2006 (has links)
It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.
16

An analysis of the seasonal and short-term variation of road pavement skid resistance

Wilson, Douglas James January 2006 (has links)
It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.
17

An analysis of the seasonal and short-term variation of road pavement skid resistance

Wilson, Douglas James January 2006 (has links)
It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.
18

MACROINVERTEBRADOS ASSOCIADOS ÀS FOLHAS EM DECOMPOSIÇÃO DE RIACHOS NEOTROPICAIS: INFLUÊNCIA DA QUALIDADE QUÍMICA, VARIEDADE DE ESPÉCIES VEGETAIS, BIOMASSA DE FUNGOS E TEMPO DE EXPOSIÇÃO / MACROINVERTEBRATES ASSOCIATED TO DECAYING LEAVES IN NEOTROPICAL STREAMS: INFLUENCE OF CHEMICAL QUALITY, VARIETY OF PLANT SPECIES, FUNGAL BIOMASS AND EXPOSURE TIME

Biasi, Cristiane 08 March 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In low-order freshwater ecosystems, macroinvertebrates have an important role in nutrient cycling, as they participate in the shredding of detritus, which are the main energy source for the trophic chain in these systems. This study aims to investigate the macroinvertebrate fauna associated to leaves of different plant species with different concentrarions of LigCel:N. Thus, we carried out four treatments. The first included Casearea sylvestris leaves and the second a mixture of C. sylvestris, Rollinia emarginata, Phytolacca dioica and Cabralea canjerana leaves. The third treatment consisted of Ficus luschnathiana leaves, and the fourth of a mixture of Trema micrantha, Inga alata, Cupania vernalis and F. luschnathiana leaves. The litter bags were used for the experiments, each containing 4.0 ± 0.1 g of leaves and after 7, 14, 21 and 28 days of incubation in the streams, four litter bags of each treatment were retrieved and analyzed. The leaves were washed for the removal of invertebrates, dried (30ºC) and destined for ergosterol analyses. All organisms were identified to the lowest possible taxonomic level and then classified in functional groups, according to feeding habits. Density of organisms, biomass and richness (through rarefaction) were determined, analyzed with a two-way ANOVA and then checked for correlations with fungal biomass using a Pearsons s Correlation test. Faunal composition was analyzed through MANOVA, NMDS, Cluster analysis and Indicator Species analysis. Significant differences were found among the treatments for macroinvertebrate density and Chironomidae density. The lower nutritional quality species (F. luschnathiana) presented the highest density and fungal biomass values and, consequently, the highest dry mass loss rate. We verified correlation between the density of organisms and fungal biomass. With this study, we verified that the macroinvertebrate community, as a whole, and also the Chironomidae specifically, are influenced by heterogeneity of the detritus and its chemical composition. However, microbial conditioning seems to be more important for this association, since it can increase the nutritional value of species typically considered of low palatability. / Em ecossistemas aquáticos de pequena ordem os macroinvertebrados têm importante papel na ciclagem de nutrientes, pois participam da fragmentação de detritos, que constituem fonte de energia para a cadeia trófica. Este trabalho visou estudar a fauna de macroinvertebrados associados a diferentes espécies vegetais com diferentes teores de LigCel:N. Assim, trabalhamos com quatro tratamentos. O primeiro tratamento compreendeu a espécie Casearia sylvestris e o segundo uma mistura de C. sylvestris, Rollinia emarginata, Phytolacca dioica e Cabralea canjerana. O terceiro tratamento teve a espécie Ficus luschnathiana e o quarto tratamento uma mistura das espécies Trema micrantha, Inga alata, Cupania vernalis e F. luschnathiana. Para o experimento, foram utilizados litter bags contendo 4,0±0,1 g de folhas e após 7, 14, 21 e 28 de incubação nos riachos, quatro litter bags de cada tratamento foram retirados e analisados. As folhas foram lavadas para a remoção dos invertebrados, secas (30°C) e destinadas à análise de ergosterol. Os organismos foram identificados até menor nível taxonômico possível e classificados em categorias alimentares funcionais. Calculamos a densidade de organismos, biomassa e riqueza rarefeita, que foram comparadas com análise ANOVA two-way e correlacionadas com a biomassa de fungos por meio de Correlação Linear de Pearson. A composição da fauna foi analisada por meio de análise de agrupamento, NMDS, MANOVA e Análise de espécies indicadoras. Encontramos diferença na densidade de macroinvertebrados e Chironomidae entre os tratamentos, sendo que a espécie de baixa qualidade (F. luschnathiana) apresentou maior densidade, maior biomassa de fungos e consequentemente a maior perda de massa seca. Verificamos correlação entre a densidade de organismos e a biomassa de fungos. Com este estudo verificamos que a comunidade de macroinvertebrados e especificamente os Chironomidae são influenciados pela heterogeneidade vegetal e a qualidade química do detrito. Entretanto, o condicionamento microbiano parece ser mais importante para esta associação, pois pode promover qualidade nutricional para as espécies de baixa palatabilidade.
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Assessing the litter removal and invertebrate communities of soybean stem detritus grown in dredge-amended soils: a Northwest Ohio field study

Tolle, Carly 02 September 2021 (has links)
No description available.
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EFFECTS OF REDUCED DETRITUS ON INVERTEBRATE COMMUNITY STRUCTURE IN COSTA RICAN HEADWATER STREAMS

Morgan, Brendan C. 31 July 2015 (has links)
No description available.

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