Generalisations about the abundance structure of species' geographic ranges may have implications within a number of areas of applied ecology. However, empirical data is largely restricted to a single taxonomic group within one geographic region. One approach to the study of range structure and its ecological consequences is to examine the relationship between demographic rates and environmental conditions. However, most studies of population processes are at small spatial scales and it is not known to what extent patterns found at these scales may be extrapolated. This thesis addresses these issues using surveying techniques to measure spatial structure in both the densities and demographic rates of the holly leaf-miner (Phytomyza ilicis Curt.) at a wide variety of spatial scales. Geostatistical tools are used to analyse the data collected. At a regional scale, spatial structure in leaf-miner densities is apparent despite considerable variation between hosts within individual habitat patches. This structure can in part be accounted for by variation in habitat and altitude. Over the entire range, broad scale trends in population density can be detected which can also, be correlated with environmental variation.' Many demographic rates components exhibit spatial structure. However, their relationships both with population density and environmental variation are more complex. Per capita mortality rates did not correlate well with population density at any spatial scale. The difficulties inherent in relating population density with demographic rates and regulation by natural enemies are discussed. The demographic approach has also been used to explain.the positive interspecific abundance-distribution relationship. Computer simulation techniques are employed to explore this model. The results indicate that the positive relationship should be extremely robust under a high degree of variation between the demographic rates. However, data from the holly leaf-miner surveys suggest that current. models of range structure make unrealistic assumptions about environmental variation. The key to understanding range structure and its consequences may lie in our ability to make. generalisations about environmental structure.

Geochemical proxy records of sea surface environmental conditions at Blake Nose indicate short-term high amplitude variations. In order to investigate the response of calcareous nannoplankton to these short-term sea-surface environmental changes, we developed a high-resolution Eocene planktonic foraminifera Mg/Ca record and calcareous nannofossil absolute abundance record for ODP Site 1052 spanning the late middle Eocene (37.85 to 37.45 Ma). These data enable direct comparison of the absolute nannofossil abundance data to geochemical paleoenvironmental proxies (Mg/Ca, ?18O and ?13C) to determine the phytoplankton response to paleoenvironmental change and whether temperature or nutrient levels exerted primary control. The nannofossil absolute abundances were estimated using a combination of the random settling technique (RST) and spiking method (SM), which are two independent methods. Both methods yielded similar and reproducible results. The calculated Mg/Ca paleotemperature record indicates a decrease in SSTs from ~33 to 28�C, while the ?18Osw values calculated from the Mg/Ca paleotemperature also decreased from ~3? at 37.83 Ma to ~2? at 37.6 Ma. The combined trends of the SST and ?18Osw suggest that continental ice did not have a major influence on the climate during the study interval. Variations in the Gulf Stream (e.g. track of proto-Gulf stream, number and transit of eddies, and Gulf Stream related upwelling), may have contributed to the reconstructed sea surface hydrographical changes at Blake Nose. However, overall weakening of the hydrological cycle as global climate transitioned from a greenhouse to an icehouse could be the major factor controlling the hydrographical changes at Blake Nose. Approximately 48 nannofossil taxa were identified in this study. These taxa have been grouped into major, minor and rare taxa based on their abundance in any given sample. Results of the statistical analyses (canonical correspondence analysis CCA, Cluster analysis, and correspondence analysis CA) used to relate the nannofossil abundance to environmental parameters did not show expected relationships between the nannofossil absolute abundance and environmental parameters. There are several explanations for this which includes dominance of biotic control over abiotic control, difference in depth habitats between the planktonic foraminifera used for the geochemical proxies and the calcareous nannoplankton, and changing combinations of environmental controls operating during the ~400 ky interval. This suggests that these factors should be taken into account when making conclusions about nannofossil environmental preferences.

Geochemical proxy records of sea surface environmental conditions at Blake Nose indicate short-term high amplitude variations. In order to investigate the response of calcareous nannoplankton to these short-term sea-surface environmental changes, we developed a high-resolution Eocene planktonic foraminifera Mg/Ca record and calcareous nannofossil absolute abundance record for ODP Site 1052 spanning the late middle Eocene (37.85 to 37.45 Ma). These data enable direct comparison of the absolute nannofossil abundance data to geochemical paleoenvironmental proxies (Mg/Ca, ?18O and ?13C) to determine the phytoplankton response to paleoenvironmental change and whether temperature or nutrient levels exerted primary control. The nannofossil absolute abundances were estimated using a combination of the random settling technique (RST) and spiking method (SM), which are two independent methods. Both methods yielded similar and reproducible results. The calculated Mg/Ca paleotemperature record indicates a decrease in SSTs from ~33 to 28�C, while the ?18Osw values calculated from the Mg/Ca paleotemperature also decreased from ~3? at 37.83 Ma to ~2? at 37.6 Ma. The combined trends of the SST and ?18Osw suggest that continental ice did not have a major influence on the climate during the study interval. Variations in the Gulf Stream (e.g. track of proto-Gulf stream, number and transit of eddies, and Gulf Stream related upwelling), may have contributed to the reconstructed sea surface hydrographical changes at Blake Nose. However, overall weakening of the hydrological cycle as global climate transitioned from a greenhouse to an icehouse could be the major factor controlling the hydrographical changes at Blake Nose. Approximately 48 nannofossil taxa were identified in this study. These taxa have been grouped into major, minor and rare taxa based on their abundance in any given sample. Results of the statistical analyses (canonical correspondence analysis CCA, Cluster analysis, and correspondence analysis CA) used to relate the nannofossil abundance to environmental parameters did not show expected relationships between the nannofossil absolute abundance and environmental parameters. There are several explanations for this which includes dominance of biotic control over abiotic control, difference in depth habitats between the planktonic foraminifera used for the geochemical proxies and the calcareous nannoplankton, and changing combinations of environmental controls operating during the ~400 ky interval. This suggests that these factors should be taken into account when making conclusions about nannofossil environmental preferences.

Key sites for the conservation of waterbirds (Aves) in Durban Bay, South Africa. Durban Museum Novitates 30: 1-14. Forty-eight monthly counts of waterbirds were conducted in Durban Bay (July 1999-June 2003). A total of 47 227 waterbirds of 79 species were recorded. Eighteen waterbird species were significantly more abundant in summer while seven were significantly more abundant in winter. Centre Bank supported 40.6% of all waterbirds, comprising mainly Palearctic waders and roosting gulls and terns. Distinct species assemblages of plovers (Charadridae) and sandpipers (Scolopacidae) were associated with the two most selected of the intertidal sites: Bayhead and Centre Bank. The assemblage at Centre Bank included three large-bodied Palearctic species (Greenshank, Grey Plover and Whimbrel), all of which occurred in abundance there and showed strong selection for this site. The assemblage which showed strong site selection for Bayhead consisted of both resident and Palearctic species, five of which are known to favour finer sediments (Ringed and Kittlitz's plovers, Common and Terek sandpipers, and Little Stint). Bayhead had a higher number of waterbird species that occurred at higher densities, when compared with Centre Bank, and showed the highest species-diversity ranking of all sites. This may be a result of the more heterogenous nature of this area. Sporting Bodies- Pelican Island had high densities of, and strong site selection by, piscivorous species and species associated with the semi-natural shorelines of this area. This site, however, supported only 8.6% of all waterbirds counted during the study period. Fish Wharf-Yacht Basin had the highest numbers and densities of Greyheaded Gulls, which utilized this area when scavenging. Other waterbird species were poorly represented here and this site had the lowest species-diversity ranking. Commercial harbour areas were the least attractive for waterbirds in terms of species-abundance values, densities and site selection. This is largely attributed to the artificial nature of these areas. It is recommended that Centre Bank receive highest priority for conservation status within the Bay. Reasons for conserving this site include: (a) the high overall abundance of waterbirds that this site supports; (b) the unique assemblage of Palearctic waders that utilizes this area, and the overall contribution that this has to waterbird diversity in the Bay; and (c) the importance of this site to roosting gulls and terns, particularly Kelp Gull which has regionally, and potentially globally, significant numbers in this area.

Abstract Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the transmission of a large number of pathogens to livestock and wild animals. In this study the presence of the genus, using light traps based at four different sites within the National Zoological Gardens of South Africa, was investigated during 2002-2004. In total, 37species were recorded, including large numbers of Culicoides irnicola Kieffer, 1913, which is responsible for the transmission of economically important arboviruses in South Africa, Europe, Middle and Far East. These results are discussed with reference to the wider Culicoides fauna in the Onderstepoort area of South Africa, their vector competence as well as biosecurity at the National Zoological Gardens.

No description available.

No description available.

Heavy metals have been detected in aquatic and terrestrial environment around the Paducah Gaseous Diffusion Plant (PGDP). However, little is known regarding their accumulation and associated effects in turtles inhabiting aquatic ecosystems near the PGDP. The current study was initiated to evaluate accumulation of heavy metals and its associated effects in aquatic turtle species and to determine species composition and abundance in ponds near the PGDP. A total of 382 turtles composed of 6 species were captured at 6 ponds during 2007 and 2008. Red-eared slider turtles (Trachemys scripta elegans) were the most abundant species (81.2% of the total number of turtles captured), and the abundance and densities ranged from 12 to 88 turtles and from 39 to 122 turtles/ha among study ponds, respectively. Only Cu concentrations in liver tissue differed among ponds, which may be associated with the age of one study pond. However, a gradient of increasing concentrations from ponds upstream to ponds midstream and downstream of the PGDP was observed for Pb and Hg in liver. Copper and Hg were detected in red-eared slider eggs. Copper concentrations in eggs were positively correlated with female Cu concentrations in kidney. Metal concentrations in turtle tissues and sediment were lower than previously reported concentrations associated with adverse effects. Total white blood cell counts, ratios of heterophils to lymphocytes, numbers of lymphocytes and eosinophils, and T-cell mediated immunity were correlated with metal concentrations. Hematocrits were not correlated with any metal concentrations in any tissues. Hemoparasites were observed in 40.7% of the red-eared slider turtles studied. Concentrations of heavy metals in turtle tissues, eggs, and sediment measured in the current study were low, and are not thought to be adversely affecting aquatic turtles near the PGDP. Although some hematological and immunological indices were correlated with some metal concentrations, further studies are needed to determine if these effects are associated with metal exposure, with hemoparasites, or other contaminants or disease.

Bacterial abundances and production, and the size distribution of oxygen metabolism and chlorophyll a concentration were followed through two seasonal cycles in the Menai Strait (North Wales, U. K. ) and during austral summer in the Southern Ocean. In the Menai Strait, spring blooms were characterised by a diatom to Phaeocystis succession. In both the Menai Strait and the Southern Ocean, meso- and microphytoplankton dominated phytoplankton production and biomass during diatom blooms. Nanophytoplankton predominated when production and biomass were low, i. e. during the summer in the Menai Strait, in waters near the Polar Front, and in some samples from the Weddell Sea. In both ecosystems substantial respiration resided in the bacterial (< 0.8 gm) size-fraction. Consequently during the Menai Strait temporal study, phasing of respiration in relation to photosynthesis was strongly influenced by bacterial metabolism and abundance changes. The respiration maximum occurred 1-2 weeks after the Phaeocystis abundance maximum. An explanation for this temporal lag was sought by considering the time scales of flow of organic material between the phytoplankton and the bacteria. The observations were consistent with routes via a slowly cycling pool, such as polymeric organic material. This pool would function as a reservoir and result in microheterotrophic respiration persisting after the decline of photosynthesis, causing a positive to negative temporal sequence in net community production. There was no evidence for differences in any measure of microbial biomass between the Southern Ocean and the Menai Strait. General relationships could be derived for both ecosystems: (a) the biomass quotient (< 20 µm phytoplankton / unfractionated phytoplankton) generally increased sharply as unfractionated phytoplankton biomass decreased, (b) bacterial biomass generally increased as phytoplankton biomass increased, (c) the biomass quotient of bacteria to unfractionated phytoplankton increased sharply as unfractionated phytoplankton biomass decreased. Different relationships were derived for the oxygen fluxes in terms of phytoplankton biomass for the Southern Ocean and Menai Strait observations. In these relationships, the oxygen fluxes were generally relatively (relative to the explanatory variable: phytoplankton biomass) higher in the Menai Strait. In contrast, a single relationship for DCR in terms of GCP was fitted for both data sets. This difference is consistent with a temperature effect on the oxygen fluxes, with GCP and DCR similarly suppressed at lower temperatures.

No description available.