Confronted with a diverse sandflat community of interacting organisms and a spectrum of physical forces, a meaningful community analysis should begin with a description of physical characteristics and faunal distributions over time. The functional importance of certain species in the community should then be investigated by using both field and laboratory experiments. Consequently, the purpose of this research was twofold: (1) to apply the methods of similarity and gradient analysis to describe the faunal gradation on an intertidal sandflat and; (2) use these data to design a predator exclusion field experiment aimed at assessing the effects of shorebird, crab and fish predation on certain infaunal and epifaunal invertebrates.

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At present not enough is known about the health of preschool children in the poorer communities of Cape Town. This study, was undertaken to assess the health and health care of preschool children in one such community: that of the Hout Bay harbour township. A clinic and community-based surveillance programme was devised to make this assessment. Data were obtained by monitoring the records at the Community Health Centre in the township. A study sample of 214 children from the community was also selected by random stratified cluster sampling. This sample was assessed by means of a questionnaire and a full physical examination. Analysis of data was performed on the IBM main-frame computer. A large number of medical problems were identified on screening the community sample. Most of these problems were minor ones and could be managed appropriately at the Health Centre. On the basis of the referral patterns and the small number of newly diagnosed functionally important health problems, the provision of health care in-the area was considered to be adequate. The high immunisation rate in the preschool children and the excellent attendance figures at the child health clinics indicates that the services provided are well utilised by the population. Dental caries was found to be a major health problem in the area. A strong case for the introduction of a dental health educational programme and for the fluoridisation of drinking water can made on the basis of these findings. An ongoing health screening programme would be beneficial. It could be accomplished by utilising appropriately trained nursing personnel.

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Hawke's Bay is situated on the east coast of the North Island of New Zealand and has experienced several earthquakes in the past during which liquefaction occurred. The 1931 Hawke's Bay earthquake is particularly interesting because it was the deadliest and one of the most damaging earthquakes in New Zealand's history. The study presented herein provides insights into the liquefaction hazards in Napier and Hastings based on the assessment of data from the 1931 Hawke's Bay event. Previous studies on the liquefaction hazard of the region have been performed, but the present work differs from those in that the liquefaction triggering and severity procedures are used to see if they can accurately predict observations from the 1931 event. Towards this end, the Cone Penetration Test (CPT)-based liquefaction triggering evaluations are used in liquefaction vulnerability assessment frameworks. It was found that liquefaction hazard in Napier is greater than Hastings. Additionally, Liquefaction Potential Index and Liquefaction Severity Number distributions across Napier and Hastings suggest that the analysis frameworks used are over-predicting the liquefaction hazard. This observation was reached through the comparison of predictions and 1931 post-earthquake observations. Possible causes for this over-prediction include the shortcomings in the analysis frameworks to account for the influence of non-liquefied layers in the profile on the severity of surficial liquefaction manifestations, shortcomings of the simplified liquefaction evaluation procedures to fully account for the depositional and compositional characteristics of the soil on liquefaction resistance, and the use of the assumption that the soils below the ground water table are fully saturated, which has been shown not to be the case at sites in Christchurch, New Zealand. The research community is still learning about earthquakes and liquefaction and this study demonstrates how historical earthquake accounts in a region can be used to assess the risk of the region from future earthquakes. / Master of Science / In light of the liquefaction-induced damage in Christchurch, New Zealand, there has been an increased awareness of the potential risk of liquefaction across New Zealand. Liquefaction is a phenomenon which occurs during earthquakes and results in a loss of strength in the soil. Hawke’s Bay, situated on the east coast of the North Island of New Zealand, has experienced several earthquakes in the past during which liquefaction occurred. The most common manifestations of liquefaction are the appearance of sand boils (i.e., ejecting water and mud), ground subsidence, and lateral displacements near “free” faces such as river banks. As part of this study, these observations were compiled in a database. The 1931 Hawke’s Bay earthquake is particularly an interesting case study because it was the deadliest and one of the most damaging earthquakes in New Zealand’s history. Thus, this study aims to provide insights into the liquefaction hazards in areas of Hawke’s Bay based on the assessment of data from the 1931 event. The liquefaction analysis is performed using procedures widely used in practice. Input to the analysis comes from geotechnical site investigations, intensity of the shaking during the 1931 earthquake, and estimated groundwater elevations at the time of the earthquake. The results from the analysis are then compared to the mapped observations from the 1931 event. The research community is still learning about earthquakes and liquefaction and this study demonstrates how historical earthquake accounts in a region can be used to assess the risk of the region from future earthquakes.

While research has shown that riparian forests are effective in reducing shallow groundwater nitrogen levels, the relative importance of the mechanisms responsible for this reduction have not been adequately addressed. This project focused on the microbial mediated process denitrification, which has been hypothesized to be a major factor responsible for decreased groundwater nitrate levels observed in forested regions. The study site was located on Virginia’s Eastern Shore and incorporated a transect extending from a field under agricultural use through a mesic forest to a distance of 91.4 meters. Groundwater flowed from a well drained agricultural field of Bojac sandy loam (coarse-loamy, mixed, thermic Typic Hapludults) and Munden sandy loam (coarse-loamy, mixed, thermic Aquic Hapludults) to a poorly drained forest soil, Nimmo sandy loam (coarse-loamy, mixed, Typic Ochraquults). Previous work along this transect reported mean nitrate (NO₃-N) levels of 1,161 ± 393 μmol·liter⁻¹ for shallow groundwater underlying the agricultural field, whereas shallow groundwater 91.4 meters into the forest had a mean concentration of 2.2 ± 2.6 μmol·liter⁻¹. Groundwater nitrate (NO₃-N) levels below ~3 meters of the water table 91.4 meters into the forest 559.5 ± 101.9 increased to approximately 250 μmol·liter⁻¹. In addition to nitrate levels, other water quality parameters and soil characteristics suggested that vertical variations of soil environments existed and therefore, must be incorporated into experimental design. Denitrification activiy was measured at various depth increments in the agricultural field and forest using an acetylene blockage technique. In addition, denitrification activity was measured after subjecting the soils to carbon and nitrate amendments. Denitrification activity from the forest was limited by nitrate at the water table and were carbon limited as vertical depth increased. Denitrification activity measured with nitrate amendments at the water table in the forest were two orders of magnitude higher than those in the field (7.37 nmol·g⁻¹·hr⁻¹ vs 0.074 nmol·g⁻¹·hr⁻¹). Dentrification activity measured with nitrate ± glucose amendments were higher at the water table in the forest, 6.88 nmol·g⁻¹·hr⁻¹, as compared to the field, 0.15 nmol·g⁻¹·hr⁻¹. Denitrifier microbial densities were measured at various vertical depths in the forest and agricultural field. Results demonstrated that denitrifiers densities at the water table in the forest were greater than those at the water table in the field. The number of denitrifying organisms per cubic centimeter of soil at the water table in the field averaged 2850 ± 1553(SD) as compared to 14,350 ± 13,369(SD) at the water table in the forest. At 0.91 meters below the water table in the field and in the forest the number of denitrifying organisms per cubic centimeter of soil were 1343 ± 1086(SD) and 3922 ± 3919(SD), respectively. The differences in denitrification measurements were due to location of the water table. The water table in the forest was located in the A horizon as compared to the water table in the field which was located in the C horizon. Results demonstrated that denitrification was an active mechanism that affected nitrate reduction in shallow groundwater in this system. Thus, riparian vegetation can be quite beneficial in reducing shallow groundwater nitrogen levels through microbially mediated processes such as denitrification. As a result nonpoint source nitrogen loadings from groundwater discharge can be reduced. / Master of Science

The younger life history stages of marine turtles (eggs, hatchlings) often fail to survive. To compensate, sea turtles nest several times/season and produce large clutches of eggs. The hawksbill produces the largest clutches (150 eggs) and the smallest hatchlings of any marine turtle. My study, done at Jumby Bay in Antigua, West Indies, was designed to determine whether they did so to compensate for loss in the nest, hatchling loss in the water, or both factors. I found that most of the eggs (79 %) survived to become hatchlings that left the nest and entered the sea. However, 88 % of the hatchlings swimming offshore were taken by predators within minutes after they began their migration. These results suggest that at Jumby Bay, large clutch size is favored in hawksbills because of predation pressures on the hatchlings. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

The larval fish assemblage in the shallow, nearshore region of a proposed marine protected area (MPA) in eastern Algoa Bay, temperate South Africa was investigated. Current velocities and direction and the swimming abilities of late-stage larvae were further assessed to determine potential larval movement to and from the MPA. In total, 6045 larval fishes were collected along two depth contours (~5m and ~15m) in the shallow nearshore of eastern Algoa Bay using stepped-oblique bongo net tows, twice per season for two years (March 2005 – January 2007). These larvae represented 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly between seasons peaking in spring with a mean of 64 larvae/100m3. Preflexion stage larvae dominated catches (75%). All developmental stages of Diplodus capensis, Engraulis capensis, Heteromycteris capensis, Sardinops sagax and Pomadasys species were found in the study area. It appears that these species use the shallow nearshore as a nursery area. Analysis of 12 months (May 2006 – May 2007) data from a bottom-moored Acoustic Doppler Current Profiler within the study area showed that offshore south eastward (39%) and onshore north westward currents (33%) dominated. The south westward current (15%) and north eastward current (12%) occurred less frequently. Current velocity decreased with depth in the nearshore, with a mean velocity of ~29 cms⁻¹ recorded at a depth of 4 m and a mean velocity of ~11 cms⁻¹ recorded at a depth of 14 m. Understanding the dispersal and movement of marine fish larvae in coastal habitats requires knowledge of active swimming abilities. The critical speed and endurance swimming of late stage larvae of two common inshore species occurring in the study area, Diplodus capensis and Sarpa salpa (Family Sparidae), were measured in a laboratory swimming chamber. The mean U-crit value for D. capensis (18.6 cms⁻¹) was similar to that of S. salpa (18.0 cms⁻¹), whereas mean endurance (km swum) was greater in S. salpa (8.4 km) than D. capensis (5.9 km). These swimming abilities exceed the average current velocities observed in the shallow nearshore providing larvae with the ability to greatly alter their passive dispersal trajectories and ultimately influence their distribution in the nearshore.