Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Supervised by Charles R. Denham and Richard P. Von Herzen. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Katharina Billups, Dept. of Marine and Earth Studies . Includes bibliographical references.

No description available.

Marine unconsolidated sediments constitute the largest ecosystems on earth in terms of spatial coverage, but there are still critical gaps in the science required to support conservation and ecosystem-based management. This is mainly due to the inaccessibility of these ecosystems in wave-exposed environments or deeper waters and the difficulty in observing biota in their three-dimensional sedimentary habitat. Currently, the physical driving processes of intertidal unconsolidated sediment ecosystems are much better understood than those of the subtidal ecosystems. However, these ecosystems are linked through water and sediment movement. This thesis, therefore, considers the continuum of unconsolidated sediment ecosystems across the entire continental shelf (i.e. intertidal to the shelf edge). The aim of this thesis was two-fold; (i) to advance the foundational understanding of biodiversity patterns and driving processes in unconsolidated sediment habitats, and (ii) to apply this knowledge in the development of a systematic conservation plan for marine unconsolidated sediment ecosystems. The South African west coast continental shelf was used as a case study in order to represent Eastern boundary upwelling regions. This study sought to investigate biodiversity patterns in macro-infaunal communities and determine their driving processes for incorporation into habitat classifications and the development of a habitat map. Systematic conservation plans require a map of biodiversity patterns and processes, and quantitative conservation targets to ensure representation of all biodiversity features including habitats.in marine protected areas. This thesis provided these key elements by classifying the unconsolidated sediment habitats and determining habitat-specific evidence-based conservation targets to support conservation of these important ecosystems. The application of these elements was then demonstrated in a systematic conservation plan for the unconsolidated sediment ecosystems of the South African west coast. Diversity patterns were examined using physical and macro-infauna data, ranging from the beach to the shelf edge (0-412 m). These data were analysed to develop two different habitat classifications, namely seascapes derived from geophysical and biophysical data, and biotopes derived from the combination of macro-infaunal and physical data. Multivariate analyses of 13 physical variables identified eight seascapes for the unconsolidated sediment samples from 48 sites on the South African west coast. These were based on depth, slope, sediment type, and upwelling-related processes (i.e. maximum chlorophyll concentration, sediment organic carbon content and austral summer bottom oxygen concentration). Latitude and bottom temperature were not considered major drivers of seascapes on the west coast because latitude closely reflected changes in upwelling-related processes and the temperature range was narrow across the shelf. This study revealed that productivity, a biophysical variable not usually included in geo-physical habitat classifications, played a significant role in the definition of seascapes on the South African west coast. It is therefore recommended that productivity be included in future seascape classifications to improve the utility of these classifications particularly in areas of variable productivity. Seascapes should, however, be tested against biological data to improve the understanding of key physical drivers of communities in unconsolidated sediment ecosystems. Macro-infaunal community distributions were determined along with their physical drivers for the unconsolidated sediments of the South African west coast. A total of 44 828 individuals from 469 taxa were identified from 48 sites representing 46.2 m2 of seafloor. Seven distinct macro-infaunal communities were defined through multivariate analyses and their key characteristic and distinguishing species were identified. These communities reflected five depth zones across the shelf, namely beach, inner shelf (10-42 m), middle shelf (60-142 m), outer shelf (150-357 m) and shelf edge (348-412 m). The processes driving the community structure of these depth zones were postulated to be tides, wave turbulence, seasonal hypoxia, habitat stability and homogeneity, and internal tides and/or shelf break upwelling, with drivers listed in order of increasing influence with depth. The middle shelf was further separated into three distinct communities based on sediment type, sediment organic carbon content and frequency of hypoxia. Variations in water turbulence, sediment grain size, upwelling-related variables and riverine sediment input were identified as the likely primary drivers of macro-infaunal community patterns. This chapter culminated in the development of a biotope classification based on the combination of macro-infaunal communities and their physical habitats (i.e. biotopes). South Africa has developed an expert-derived National Marine and Coastal Habitat (SANMC) Classification System which is used as a biodiversity surrogate in ecosystem assessment and spatial planning. This thesis tested the validity of this classification and the data derived Seascape classification against macro-infauna species abundance and biomass data in an effort to determine how well the different classifications represent macro-infaunal diversity of the west coast. These two classifications were also compared to the Biotope classification which combines macro-infaunal communities with their physical habitats. A canonical analysis of principle coordinates (CAP) was utilised to test the success with which each sample was allocated to the relevant habitat type in each classification. The total allocation success for each classification was used as a measure of effectiveness in terms of representing biodiversity patterns. Both classifications had similar allocation successes of 89-92 percent and 92-94 percent for the Seascape and National Habitat Classification respectively, but either over- or under-classified the macrofauna communities. The Biotope classification had the highest allocation success (98 percent), therefore it is the most accurate reflection of the macrofauna biodiversity patterns on the west coast. A key finding of this study was the increasing accuracy of classifications from physically- to expert- to biologically-derived habitat classifications. In this thesis, the Biotope classification was deemed the best representative of biodiversity patterns and was therefore used to produce the Biotope map for use in spatial assessment and planning. The distinct depth patterns that emerged in both the Seascape and Biotope classifications highlighted the need for further investigation of the relationship between depth and biodiversity. Despite variability in macro-infaunal communities, a general unifying pattern in biodiversity across the shelf was sought. Three relationships between depth and species richness have been described in the literature; namely a unimodal pattern, a positively linear relationship with depth, and no relationship between depth and species richness. These hypotheses were tested on the west coast. Two different species richness metrics were utilised to test the depth-diversity relationship, namely observed species density (spp.0.2m-2) and estimated species richness (spp.site-1). Observed species density increased from the beach to the shelf edge (350 m), then decreased to 412 m. The decline may have been due to difficulty in detecting species at greater depths as a result of sampling challenges. The inclusion of an innovative extrapolative method for estimating species richness (the capture-recapture heterogeneity model) within the Bayesian statistical framework mitigated the effects of species detection heterogeneity and revealed that species richness actually increased continuously across the shelf from beach to shelf edge. Thus the general relationship between depth and species richness is positively linear on the west coast of South Africa The new macro-infauna dataset and biotope map provided the opportunity to develop the first habitat-specific evidence-based conservation targets for unconsolidated sediments of the west coast. Species-Area Relationship (SAR) based conservation targets were developed for the biotopes using a modification of the generally accepted methodology. The accepted methodology has three steps (i) the estimation of total species richness for each habitat using the Bootstrap asymptotic estimator, (ii) the calculation of the slope of the species area curve (i.e. the z-value), and (iii) the calculation of targets representing 80 percent of the species. The inclusion of an innovative extrapolative species richness estimator, the Multi-species Site Occupancy Model (MSOM) provided better species richness estimation than the more conventional bootstrap species richness estimator, even though both are based on species accumulation. The MSOM, applied in the Bayesian statistical framework takes detectability of a species into account.

The evolution of the sulphur content of humic substances extracted from a near-shore sediment core was investigated. Special attention was taken to avoid S contamination of the humic materials during sample handling and extraction. The S/C ratios increased continuously with depth to values which strongly suggest S addition to the humic matrix during early diagenesis by reactions between organic matter and H₂S or its oxidation products. The light isotopic composition of this organic sulphur supports this view; however, subsequent isotopic exchange has obscured the mechanism initially involved. Since a large fraction of the enrichment occurred above the sulphidic zone, redox boundaries, such as the interface of anoxic microniches within the more oxidized zones, or the sulphidic/suboxic boundary of the sediment column, must have been important sites for S addition. The influence of sulphur enrichment on the complexing capacity of humic materials was also investigated, and it was shown that S-addition increases significantly the number of sites on which Cu is irreversibly bound. Iodine is characteristically enriched at the surface of hemipelagic and nearshore sediments deposited under oxygenated conditions. In such sediments, bulk I/Corg ratios usually decrease with depth to values which are characteristic of anoxic sediments, reflecting a preferential release of iodine during early diagenesis. There is some debate as to whether sedimentary iodine is associated with the iron oxyhydroxide phase or with the organic fraction, and whether the decrease in I/Corg with depth is due to the dissolution of the iron oxyhydroxides or the decomposition of labile organic matter. In this study, it is shown that in a surficial hemipelagic sediment sample and in a nearshore sediment core iodine is mainly associated with the organic fraction and, moreover, that humic substances are involved in the surficial iodine enrichment. Laboratory experiments on the uptake and release of iodine by and from sedimentary humic substances also suggest a mechanism whereby humic materials reduce iodate at the sediment/water interface to an electrophilic iodine species which further reacts with the organic matter to produce iodinated organic molecules. During burial, this excess iodine could be displaced from the organic matrix by nucleophiles such as sulphide ions or thiosulphate, thus providing a possible explanation for the decrease in I/corg ratio with depth observed in many nearshore and hemipelagic sediments. Bulk metal concentrations were measured in the sediments of Saanich Inlet in an attempt to establish the occurrence of trace metal enrichments in the anoxic central basin. Ba, Ni, V, Cr, Zn, Pb, Cu, and Mo were found to be enriched in the anoxic ooze over the possible contributions from lithogenous sources. Spatial and seasonal variations in the chemical composition of the settling particulates collected with interceptor traps gave further indications of the mode of incorporation of these metals. Biogenic Ba and Cr appeared to be associated with opaline silica, although alternative explanations are also possible, particularly for Ba. Zinc seemed to be added to the sediment essentially in association with planktonic materials, while Cu required an additional source directly linked to the anoxic environment. Similarly, Ni, V, and Mo were added to the anoxic sediments by reactions occurring at the sediment-water interface. In the nearshore environment studied here, these metals were not associated to any significant extent with planktonic materials, particularly Ni and Mo. Of all the elements analyzed, Mo showed the largest enrichment in the anoxic sediments of Saanich Inlet. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Viable cysts collected from natural sediments were induced to excyst. Ten cyst-theca relationships, first established elsewhere, were confirmed for British Columbia (B.C.). These were: Gonyaulax tamarensis, Protoperidinium aspidotum, P. claudicans, P. conicoides, P. conicum, P. cf. denticulatum, P. leonis, P. oblongum, and P. punctulatum. Five cyst-theca relationships were established for the first time: Peridiniopsis cf. hainanensis, Protoperidinium sp. nov., P. thorianum, and two apparently new species of Gonyaulax. P. pentagonum was found to have a cyst different from the cyst of this species in the Atlantic. Forty-five samples from Recent sediments were collected along the coast of B.C. Twenty-three of the samples had very few cysts. Hidden Basin was the chief source of viable cysts for the excystment experiments. Ten cyst-based taxa were described from the sediment samples. These were: Operculodinium centrocarpum, the cyst of Scrippsiella faeroense (= Micrhystridium bifurcatum), Spiniferites belerius, S. bentori, S. bulloideus, S. elongatus, S. membranaceus, S. nodosum, and S. ramosus. Tanyosphaeridium sp. has been recorded previously as the cyst of Polykrikos schwarzi. Two new cyst-based taxa are described for the first time. These are a cyst of Protoperidinium sp., and Spiniferites "sp. A". Cyst assemblages in the Recent sediments of B.C. were similar to many temperate estuarine and neritic areas. Some cysts which are characteristic of these areas in other regions, have not yet been found in B.C. The relative importance of some cysts also varies from that found in similar sediments elsewhere. The dominance of Operculodinium centrocarpum in many of the cyst assemblages, including B.C., is a pattern typical of temperate estuarine conditions. Some cysts appear to be characteristically associated with fjord environments. Scrippsiella faeroense, for example, has been found in Norwegian fjords and Scottish sea lochs as well as some B.C. fjords and inlets. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate

The study of suspended sediment provides insights into the transport and accumulation of sediment in depositional basins. Past investigations have suffered, however, from a lack of methodology that can deal with the low concentrations of suspended sediment. The theory and method of three techniques to be used in the analysis of suspended sediment have been outlined. 1) VSA, provides a rapid, accurate and precise method of determining grain size distributions of low weight samples. The method is based on the solution to a set of equations that discretely define the increasing volume of a homogeneous sediment sample settling in an enclosed volume of water. The results are in terms of sedimentation diameters, a hydrodynamically sensitive property. 2) The Ag filter mount provides a fast technique for a low sample weight random oriented mount to be used in quantitative XRD analysis. The method has excellent precision and does not fractionate the mineral component due to their settling velocity. 3) Suspended sediment collectors have been used to measure the downward flux of sediment in the fjord environment. The traps have also provided a means to calculate the natural settling velocity of flocculated or otherwise enhanced particle settlement. Laboratory and field studies have dealt with the interaction of zooplankton with suspended sediment. Marine zooplankton ingest suspended sediment at a rate dependent on sediment concentration and mineralogy. Ingested mineral particles undergo chemical and mineral transformations which are functions of mineralogy, cation exchange capacity and residence time in the digestive tract. Zooplankton fecal pellets have a much larger settling velocity than their component particles. This increased settling rate allows clay to be deposited where the hydrodynamic nature of the environment would only allow coarse silt to fine sand deposition. Glacial flour (feldspar, quartz, trioctahedral mica, chlorite, amphibole, tourmaline, and vermiculite) enters the surface-layer of the Howe Sound fjord as a sediment plume which moves quickly down inlet while slowly mixing with the marine water. Although flocculation occurs in the lower brackish water of the surface-layer, mixing and diffusion are the dominant means for sediment to enter the lower-marine-water. Once in the lower-marine-water, zooplankton pelletization and biologic agglomeration of inorganic floccules takes place. These processes that enhance the individual particle settlement, generate a fast response time between the surface-layer and the lower-marine-layer in terms of sedimentation of particulate matter. Settling velocities of particles less than 1 μm have been enhanced over 1400 times. Size distributions of sediment deposited on the sea-bed are a function of variable multimodal and/or non log-normal size distributions from sub-laminae falling through the water column. The increase in deviation away from log-normality down inlet, for size distributions of both suspended and deposited sediment, is an artifact of the size analytical method. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Harmful organic contaminants, such as petroleum hydrocarbons, are ubiquitous in coastal marine ecosystems around the world, a problem that will only be exacerbated with rising sea level and increased inundation of coastal urban areas. Therefore, it is necessary to understand the fate of these contaminants following their deposition on marine sediment, where they can potentially persist for long periods of time. As organic carbon remineralization rates depend on the respiration process employed by the bacteria in the sediment, it was the goal of this study to determine how the sediment redox environment, with an emphasis on Fe redox chemistry, affects the biodegradation of recalcitrant petroleum hydrocarbon compounds. While amendment of natural sediment with Fe minerals that are commonly transported to coastal areas following erosion from continental crust did successfully catalyze Fe reduction and inhibit sulfate reduction, the effect on the hydrocarbon biodegradation rate was negligible. However, inoculation of the sediment with Shewanella oneidensis, an exoelectrogenic, Fe reducing bacteria known to catalyze the degradation of hydrocarbon compounds found in crude oil, did significantly affect the redox environment and sediment microbial communities and alter the pattern of hydrocarbon loss in the sediment over time. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1966. / Vita. / Bibliography: leaves 137-143. / Ph.D.

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