No description available.

In 1996, four cores (∼30 cm depth) were extracted from the high marsh zone of Dipper Harbour salt marsh in the Bay of Fundy. Soil bulk densities are shown to be controlled by mineral density and are higher than those reported for salt marshes in the northeastern United States. Examination of variations in mineral content suggests that regular tidal action and ice rafting deposits the majority of the mineral sediment to the high marsh zone. Dating techniques (based upon pollen, 137Cs, 210Pb and total Pb) were applied to selected cores, suggesting accretion rates from 0.25 to 0.31 cm yr-1 which are higher than the rates of local relative sea level rise. Correlation of trace metal densities (Cu, Fe, Pb and Zn) to Al densities were used to justify Al normalization. After consideration of natural sources and adsorption factors, the normalized Pb profiles are shown to reflect historical pollution levels of leaded gasoline consumption. Carbon storage values in the upper 25 cm of sediment range from 7.3--10.5 kg C m-2 and carbon accumulation rates vary from 95 to 124 g C m-2 yr-1, representing 15--29% of the salt marsh macrophyte productivity.

No description available.

Research into seed biology and restoration ecology of areas disturbed by mining is crucial to their revegetation. Shark Bay Salt, a solar salt facility in the Shark Bay World Heritage Area in Western Australia has several areas of disturbance as a result of 'soil borrowing'. Soil from these areas termed 'borrow pits' was used to create infrastructure such as the roads and embankments surrounding the evaporation ponds. Many of the pits contain little to no vegetation after >10 years since disturbance ceased, hence research into their restoration is now essential. A vegetation survey at the site established the key species in the undisturbed vegetation, and investigated the vegetation in borrow pits subject to natural migration and topsoil replacement. The vegetation communities in the borrow pits were vastly different to those in the undisturbed vegetation, highlighting the need for research into revegetation. An investigation into the use of 'borrowed' topsoil on a small scale showed that seedling recruitment from 'borrowed' topsoil was generally similar in the donor site (natural vegetation) and the borrow pits. Due to the absence of topsoil for further revegetation, it was necessary to understand seed germination and dormancy characteristics to establish seed pre-treatments prior to seed broadcasting and seedling (greenstock) planting. An investigation into seed germination and dormancy characteristics of 18 common species revealed that most species germinated equally well at 26/13oC and 33/18oC, however seven species had improved performance at 26/13oC. Untreated seeds of seven species exhibited high germination. Seeds of two species had low imbibition, which increased with hot-water treatment, and hence require scarification for germination. Germination of seeds of three species substantially increased with gibberellic acid (GA3), smoke water (SW) and karrikinolide (KAR1, a butenolide isolated from smoke). Seeds of the remaining six species had low germination regardless of treatment. As a result, species were classified as likely to be non-dormant (44%), physiologically dormant (44%) or physically dormant (11%). Physiological dormancy of three species was at least partly alleviated by dry afterripening, whereby moisture content of seeds was adjusted to 13% or 50% equilibrium relative humidity and seeds were stored at 30oC or 45oC for several months. All iv after-ripening conditions increased germination percentage and rate of two species with one only germinating when treated with GA3 or KAR1. The germination of the third species was dependent on after-ripening temperature and seed moisture content.

No description available.

[Truncated abstract] Sponges have an invaluable ecological importance through the provision of shelter and habitat, consolidation of reefs, bio-erosion, and in benthic-pelagic coupling processes. In addition, sponges are known to be an incredible source of compounds with bio-medicinal and commercial applications. Despite their ecological and economic importance, our understanding of the processes which maintain and structure sponge populations is severely lacking compared to other sessile invertebrates (e.g. Cnidarians). This study examines the processes which help maintain and the factors which structure the populations of two sympatric Haliclona species (Demospongiae; Haplosclerida; Chalinidae) at Hamelin Bay on the south west coast of Australia. In addition, the importance of both species to the broader marine community is examined. The reproductive biology of both species was determined from histological sections taken from each species over two years at Hamelin Bay. No evidence of asexual reproduction was observed in either species. Sexual reproduction occurred from November to April in Haliclona sp. 1 (hereafter green Haliclona) and November to May in Haliclona sp. 2 (hereafter brown Haliclona). The green Haliclona is viviparous with both gonochoric and hermaphroditic individuals observed in the population. The brown Haliclona is also viviparous with separate sexes. The onset and progression of reproduction in both species corresponded to increases in water temperature and photoperiod, but only decreasing wave height showed a significant correlation to gametogenesis. ... A significant (P < 0.05) difference in concentration between seasons was also observed, suggesting environmental and physiological factors affect the production of salicylihalamide A in the green Haliclona. The importance of each species to the marine environment was assessed by investigating the endofauna inhabiting each species across their known range ( [approx. ]1000 km's). A total of 948 and 287 endofaunal individuals were found associated with the green and brown Haliclona, respectively. Twenty four endofaunal taxa were found (from mysid shrimps to teleost fish), and the endofaunal assemblages of each species were significantly different. However, only the endofaunal assemblage associated with the green Haliclona varied among locations. Overall, this study demonstrates that the populations of both species are maintained by limited sexual reproductive output and larval dispersal. Abiotic factors (e.g. water temperature, wave exposure) influence the growth and physiology of both species, which is intimately connected to their abilities to reproduce. This has important consequences for the species populations with regard to their resilience to environmental change, and potential for harvesting of biomass for supply of bioactive compounds. Additionally, both species provide important habitats for many other organisms. The findings highlight the need for a detailed understanding of the ecology of potentially exploitable sponge species, to ensure their conservation and limit the impact on the organisms which rely on the sponges.

Thesis (M.A.)--University of Manitoba, 2001. / Includes bibliographical references.

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The objectives of this research were to determine the prevalence of gestational diabetes mellitus (GDM) among the Cree of James Bay, identify independent risk factors for GDM and infant macrosomia in this population and compare the risk for GDM and infant macrosomia among Cree women with Canadian non-Native women. The prevalence of GDM using the National Diabetes Data Group criteria among the Cree was 12.8% (95% CI: 10.1--15.5), among the highest ever reported for an Aboriginal group. Independent risk factors for GDM among the Cree were advanced age, pregravid overweight and previous GDM. A comparison of risk of GDM between Cree and non-Native women revealed a significant interaction between ethnicity and pregravid weight. Overweight Cree women were at an elevated risk for GDM compared with overweight non-Native women (OR: 2.3, 95% CI: 1.3--3.8), whereas the risk for GDM was not statistically different between normal weight Cree and non-Native women (OR: 1.4, 95% CI: 0.7--2.7) after adjusting for age, parity, and smoking status. Mean birth weight among Cree infants was 3859 +/- 519 g, the highest reported for any ethnic group in the world. Macrosomia prevalence was also high at 34.3%. Independent risk factors for macrosomia among the Cree were advanced age, pregravid overweight and GDM. A significant interaction was noted between ethnicity and GDM on risk for macrosomia. GDM increased the risk for macrosomia 4.5-fold among the Cree but had no significant effect among non-Natives. After adjusting for age, parity, pregravid weight, gestational weight gain, GDM, gestational duration and smoking status, Cree infants remained heavier than non-Native infants by 235 g. The results of this research indicate the need to control pregravid obesity through culturally acceptable dietary modifications and exercise in order to minimize the risk for GDM among Cree women. The significant impact of GDM on risk for macrosomia among the Cree calls for the re-evaluation of the existi

Approximately 98 % of South African exports are conveyed by sea. The volume of South Africa's sea trade represents approximately 3,5 percent of world seaborne trade in tonnage terms, a performance that placed the country on the map of international maritime nations. The major portion of South Africa's dry-bulk exports is shipped from the port of Richards Bay. Richards Bay is the seventh largest world port in terms of cargo volumes, and handles in excess of 80 million tons per annum. This represents approximately 57 % of all South African seaborne trade by volume. The greater portion of South African seaborne trade, especially on the export side consists of shipments of primary (raw) products or beneficiated primary products, and accounts for approximately 140 million tons of all cargoes. The export of primary products or commodities is a vital part of the South African economy and generates a substantial amount of the country's foreign exchange. This dissertation concludes that shipment on FOB terms continues to command the lion's share of all export consignments handled in the port. In fact from the more than 78 million tons of cargo covered in the survey, more than 64 million is shipped on FOB terms, which constitute in cargo volumes approximately 82% of all exported commodities from the Port of Richards Bay. The high incidence of shipments on FOB terms leaves the final arrangement of shipping in the hands of foreign buyers. This represents a substantial loss of revenue in invisible earnings for the country's service account of the balance of payments. / Thesis (M.Com.)-University of Natal, Durban, 2003.