The development of a late Holocene salt marsh was studied on the inactive part of the Fraser Delta at Boundary Bay, southwestern British Columbia. Present-day vegetation zones near 64th Street, South Delta, in the western part of the Bay, were distinguished in the salt marsh and were related to zones found in cores obtained in a transect across the marsh. A sequence of development, related to elevation, was determined. Salicornia and Triglochin are pioneer colonizers of the tidal flats and are sometimes associated with areas elevated by algal mats. As the area was elevated, sediments were trapped by vegetation and stabilized by rhizomes, and other halophytes grew, including Cuscuta, Sperqularia, Atriplex, Distichlis, Grindelia, and Plantago. A zone characterized by abundant Atriplex represents positions of former strandlines. As further emergence occurred, mesophytes became dominant and, in the landward, most emergent zone, a diverse flora of Maius, Sjdalcea, Aster, AchiIlea, Solidaqo, Elymus, Angelica, Juncus, and grasses developed. A radiocarbon date on Salicornia-rich organic silts at a depth of 35 to 40 cm in core 5 suggests that salt marsh development commenced 320 ± 70 years B.P. (GSC-3186). A former salt marsh peat is now partially buried and being actively eroded where exposed near 112th Street, South Delta, in eastern Boundary Bay. A paleoenvironmental reconstruction suggests the peat started developing in freshwater, with ferns, sedges, Typha, and Nuphar. Later, it was successively inundated by marine water and a salt marsh developed, as seen by an increase in the abundance of chenopod pollen. Subsequent emergence of the salt marsh was accompanied by the development of an increasingly diverse vegetation. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The abundance and microspatial distribution of harpacticoid copepods were studied from Jan 1977 to Jan 1980 at two intertidal sites on the Fraser River Delta, B.C.: one (Sand) on the crest of a sand wave and the other (Mud) on the edge of its muddy trough. Eight species formed the communities at the two sites. The composition of the communities was studied by biweekly survey in 1978. Longer term changes in the organization of the sand community were followed by annual mid-winter surveys over four years. Factor analysis was used to group species with similar patterns of seasonal occurrence and macrohabitat distributions. Microspatial patterns in the two communities were compared by heterogeneity chi-square analysis from random core samples collected monthly. The distribution of species relative to small-scale hydraulic bedforms (sand ripples) was studied at the sand site. Distinct patterns of community organization were seen at the two sites. The mud community was characterized by high temporal overlap of species; the sand species showed a distinctive pattern of temporal segregation. Although species in both communities were segregated at small spatial scales, microspatial partitioning was stronger and seasonally more variable in the mud. Spatial patterns in the sand were related to the rippled bedforms. Biogenic structuring by macrobenthos and disturbance by predators were implicated as the causes of microspatial patterns observed in the mud community in summer. Although the two communities showed distinct features of organization they were not completely isolated. Two mud species, Scottolana canadensis and Tachidius triangularis, 'migrated' to the sand in summer. The role of biological interactions in structuring the communities was investigated. Predation by small tidepool fish, Clevelandia ios and Leptocottus armatus, was studied by gut analysis. Predation was species- and size-selective, with two epipelic species, S. canadensis and T. triangularis, occurring most frequently in fish gut samples. A morphometric basis for ontogenetic variation in predation by C. ios was proposed. Evidence to support the hypothesis that competitive interactions help to structure harpacticoid copepod communities was found in changing patterns of abundance, changing patterns of microhabitat use and morphometric character displacement over four years. Competitive interactions were highly dynamic and appeared to be part of the cause of both the temporal and microspatial segregation observed in the sand community in 1979. By 1980, the eight species present in the January sand community formed a displacement series in body sizes. Although each harpacticoid community is unique, numerous parallels exist between the structure and function of the Iona North assemblage and those from shallow water habitats, worldwide. It is clear, therefore, that the conclusions from this research have more than local significance. / Science, Faculty of / Zoology, Department of / Graduate

In this study, three cores obtained from Burns Bog just south of the Fraser River in Delta, British Columbia, were analyzed palynologically. The paleoecology of the bog was reconstructed from the results of these analyses, together with data from vegetation studies of the bog, pollen rain and surface pollen spectrum investigations of selected wetland environments, as well as pollen tetrad and pollen productivity studies of bog ericads. The vegetation of Burns Bog was sampled by estimating species cover in selectively placed 100 m² quadrats. These field data were used in combination with an air photographic mosaic to map the eight vegetation types of the area. The palynomorph "fingerprints" of selected wetland environments, determined from pollen rain and surface pollen spectrum studies, were used to recognize analogous phases recorded in cores. Tetrad diameter and pollen productivity data for bog ericads assisted in recognizing ecologically significant ericad species that distinguished wet and dry raised bog phases. The study shows that Burns Bog has developed on Fraser River deltaic deposits which appeared above sea level just after 5,000 years BP. The seemingly synchronous emergence of the three core sites and a locality in adjacent Boundary Bay indicate a possible relative sea level decrease at this time. The silty emergent sediments are characterized by high percentages of Pinus and Picea pollen deposited by river water, and Cyperaceae pollen from local Scirpus and Carex stands. Following this emergence, sedges colonized the area, forming a sedge peat containing abundant Cyperaceae pollen. At the western end of the bog, a salt marsh developed (4,125 ± 110 BP) in response to a marine advance. This was possibly caused by a shut-off of fresh-brackish water from the Fraser River when the delta reached Point Roberts. In the eastern section of the bog, at the foot of Panorama Ridge, the sedge phase was only transient. A Myrica-Spiraea-Lysichitum swamp developed, remaining until very recently. After the sedge phase in the central part of the bog, Myrica and Spiraea thickets appeared; these were subsequently replaced by Sphagnum bog at 2,925 ± 85 years BP. In the western end of the bog, sedges were replaced by heaths, predominantly Ledum. At the foot of Panorama Ridge, Sphagnum arrived very recently. Pines seem to have invaded all sites at the 2.00 m level. The AP pollen spectrum shows that the regional upland vegetation remained unchanged throughout the history of Burns Bog until settlers cleared the forests. On the delta, however, fluctuations in alder pollen were probably associated with alder colonization of levees and swamps near the channels. Fire has played an important role in bog ecology. Natural Sphagnum accumulation processes are modified because fire destroys the vegetation of slightly higher, dry sites. Unburned wet depressions then become centers of peat accumulation. These sites eventually rise above the surrounding burned areas, which are converted to depressions. A model for raised bog development is proposed for the Fraser Lowland. The prograding delta-front is colonized by emergent aquatics growing on silts. This phase is followed by the advent of a sedge swamp perhaps containing some wetland grasses. Eventually, shrubs such as Myrica and Spiraea begin to appear, accompanied in the later stages by Ledum groenlandicum. Increased acidity of the substrate due to peat accumulation promotes Sphagnum, which eventually takes over and results in the establishment of raised bog conditions. This study, the first detailed outline of raised bog development in western North America, provides a framework for further investigations of bogs in the area. / Science, Faculty of / Botany, Department of / Graduate

Benthic algal ecology and primary pathways of energy flow were considered on the Squamish River delta at the head of Howe Sound, a fjord-type estuary. The study elucidated the structure and function of major autotrophic components of the estuarine ecosystem. Benthic algae were investigated with regard to species composition and distribution and the capacity for energy conversion, input to the system and storage. Comparisons were made with existing information on the vascular plant component of the ecosystem. The benthic algal community was studied by regular field sampling of major macroalgae and microalgal associations with a monitoring of physical-chemical environmental factors. Presence of an alga in the estuary was a function of its osmoregulatory capabilities. Establishment and temporal-spatial distribution patterns were controlled by substrate-habitat preference and availability and the interaction of light, interspecies competition, desiccation, temperature and salinity, light being of greatest importance. Carex lyngbyei Hornem., the dominant vascular plant, had a significant effect on distribution of benthic algae through light restriction during Its summer growth period and action as a substrate during the winter. Total species diversity, biomass and distributional area of benthic algae were greatest at the latter period. The effect of ecosystem structure on function was investigated by analysis of energy flux through major benthic algal producers. Comparisons were made of the total amount of energy input attributable to benthic algae and vascular plants. The importance of an algal producer to energy flux•m⁻² was a function of either high primary productivity, photosynthetic efficiency and caloric content, or in the case of diatom dominated micro-algal associations, high caloric content alone. Distribution, reflecting the presence of suitable substrate-habitat, modified this pattern. Macroalgae having high energy input•m⁻² (Monoetroma oxyapermum (Kutz.) Doty, Pylaiella littoral-is (Lyngb.) Kjell.) were of minimum importance to total energy input. Two microalgal associations (Association E, diatom dominated, Association G, Ulothrix flaoca (Dill.) Thur. dominated), each with low energy input-m but with wide distribution and high photosynthetic efficiency and caloric content contributed a total of 8H% of available energy attributable to benthic algae. Benthic algae account for a maximum of ca. 7% of total energy input to the delta ecosystem compared to ca. 90$ by vascular plants and 3% by addition of organic matter. The majority of energy for the detrital based ecosystem comes from vascular plants and becomes available after a lag period allowing decomposition. Benthic algae are significant to the ecosystem as a readily available, continually present energy source requiring little or no breakdown for utilization and not for total energy input. Energy is available as either dissolved or particulate organic matter. Of the latter, ca. 49$ is removed to the estuary, 33% incorporated into the sediments of the delta and 18$ used by consumers in the delta ecosystem. / Science, Faculty of / Botany, Department of / Graduate

Nigeria’s petroleum industry is the lynchpin of its economy. While oil has been the source of immense wealth for the nation, that wealth has come at a cost. Nigeria’s main oilproducing region of the Niger River Delta has experienced tremendous environmental degradation as a result of decades of oil exploration and production. Although there have been numerous historical works on Nigeria’s oil industry, there have been no in-depth analyses of the historical roots of environmental degradation over the full range of time from the colonial period to the present. This thesis contends that the environmental degradation of Nigeria’s oil producing region of the Niger Delta is the direct result of the persistent non-implementation of regulatory policies by post-independence Nigerian governments working in collusion with oil multinationals. Additionally, the environmental neglect of Nigeria’s primary oil-producing region is directly traceable back to the time of colonial rule. Vital to this argument is the view that the British colonial state created the economic institutions which promoted Nigerian economic dependency after independence was achieved in 1960. The weakness of Nigeria’s post-colonial dependent system is exposed presently through the continued neglect of regulatory policies by successive post-colonial Nigerian governments.

The lower Mississippi River alluvial valley (LMRAV) in northwestern Mississippi is characterized by a flat landscape and predominantly agricultural land use. The fluctuations in surface heat flux throughout the crop cycle due to land cover modifications are thought to have an impact on the regional weather. This research analyzes changes in convective patterns over the LMRAV based on the rapid variations in land cover as a result of the seasonal harvest cycle. Focusing on synoptically weak days between 2012-2016, data from the GOES 13-15 satellite visible imagers were used due to their 1-km spatial resolution and ability to distinguish lower clouds over a warm surface. By comparing the spatial and temporal patterns of convective clouds, the study confirmed that convective patterns do change based on land cover evolution resulting from the harvest cycle. These changes were likely a result of low-level thermal and moisture changes resulting from variations in evapotranspiration.

No description available.

Rice production plays an important role in the economy of the Mekong River Delta (MRD), but rice production is endangered by sea-level rise and the associated increased incidence of salinity intrusion. This study examines the diffusion of salt-tolerant rice varieties (STRVs) in the MRD that were promoted through Consortium for Unfavorable Rice Environment (CURE) activities. Evidence is found of widespread adoption in salinity-prone areas, with CURE related varieties covering 47% of rice area in at least one of two growing seasons surveyed, but that adopting areas are highly clustered. Multivariate analysis reveals that location characteristics associated with high risk of salinity inundation, rather than individual characteristics associated with household risk preferences, explain the observed pattern of adoption in the MRD. In particular, CURE-related varieties are disproportionately likely to be adopted in non-irrigated areas and in irrigated areas that are not protected by salinity barrier gates. The results imply that CURE has effectively targeted unfavorable rice growing environments and that efforts to further diffuse STRVs need to both increase the area of suitability through further varietal adaptation and promote adoption in existing suitable areas by taking advantage of strong neighborhood externalities in household adoption decisions. In terms of varietal performance, inconclusive evidence is found of higher yields of CURE-related varieties in a low-salinity year. Further, any yield gains are more than off-set by lower market prices for CURE-related varieties. / Rice is a staple crop in the Vietnamese diet and one of Vietnam's leading exports. The Mekong River Delta (MRD) accounts for more than 90 percent of rice exports. However, rice production in the MRD is endangered by saltwater intrusion due to rising sea-levels. Farmers have adopted rice varieties that are tolerant to rice to reduce their production risk that were promoted through Consortium for Unfavorable Rice Environment (CURE) activities. This study examines the rates of adoption of these CURE-related varieties, the reasons farmers choose CURE-related varieties, and variety performance on farmers' fields. Results from a household-level survey show at 47% of fields in salinity-prone areas of the MRD grow a CURE-related variety in at least one of the areas two main rice-growing seasons. Farmers are particularly likely to adopt CURE-related varieties on fields that are not protected against salinity intrusion by gates. Adoption decisions are also highly correlated with neighbors’ decisions within villages. Finally, CURE- and non-CURE-related varieties yields are similar in a year with low levels of salinity intrusion. But revenues from CURE-related varieties are slightly lower due to their lower market price, suggesting CURE-related varieties are a relatively low-cost insurance policy for MRD rice farmers in salinity-prone areas against future salinity intrusion.

Thesis (MSc) -- Stellenbosch University, 1973. / The Marble Delta is an area of approximately 40 sq. km in Natal (30°22' Long., 30°40' Lat.), occupied by Precambrian marble and associated granites. The deeply dissected country was geologically mapped on a scale of I : 6 000. A new lithostratigraphic classification of the metasediments is proposed. The base of the lowermost Le Joncguet Formation (composed of dolomitic marble and siliceous beds) is not exposed. This is followed by the predominantly ca.lcitic Oribi Formation with interbedded dolomite and graphitic layers. The marble is unconformably overlain by the Cherrywillingham Formation which comprises mainly amphibolite and granulite. The .three formations together constitute the Marble Delta Group. The main petrological units are calc-silicate marble, metaquartzite, dolomite marble, cluster serpen~ine marble and ce,lcite marble. Graphite layers are considered to have originated in situ from organic remains; there is occasional evidence of ionic transfer of carbon from this graphite by magmatic fluids. The common mineral assemblages are diopside + calcite + dolomite, tremolite + calcite + diopside + quartz, calcite + quartz + dolomite, forsterite + calcite + dolomite, plagioclase + cordierite + garnet + quartz, amphibole + clinopyroxene + plagioclase, hornblende + clinopyroxene + calcite, wollastor~te + calcite + diopside. Other minerals are graphite, antigorite, chrysotile, sphene, spinel, clinohumite, chondrodite, zoisite, clinozoisite, hedenbergite, phlogopite, ilmenite, hercynite, dravite, cummingtonite, talc, apatite, microcline, saponite. The mineral assemblages resulted from regional metamorphism and polyphase contact metamorphism.

published_or_final_version / abstract / toc / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning