Major (Fe, Mn, Al) and minor (Cr, Mo, Pb, Zn, Cd) element analyses of metalliferous sediments in cores from the East Pacific Rise and Bauer Deep indicate that the Bauer Deep sediments are similar in chemistry and origin to metalliferous sediments of the East Pacific Rises. Fe, Pb, and Zn are strongly associated in both cores and are probably related to the hydrothermal processes which are postulated to occur on the East Pacific Rise. Incomplete Cd data suggest that Cd may also be released during hydrothermal leaching of basalt Mn may originate by precipitation from hydrothermal solutions or by normal authigenic precipitation from sea water. The similar accumulation rates of Mo in both cores, and poor correlation of Mo with Fe imply that Mo is being extracted from sea water. The low abundances of Cr and Al in metalliferous sediments suggest that detritus is a minor component of the sediments. Poorly crystalline smectites constitute a major mineralogical phase of metalliferous sediments. Chemical and mineralogical studies indicate that the smectite is an iron-rich montmorillonite, similar in composition to the bulk sediment. Information on sedimentation rates in the two cores indicate that most elements are accumulating faster on the East Pacific Rise than in the Bauer Deep. Accumulation rates of metals in the Bauer Deep have decreased up to the present and are currently similar to those for normal pelagic sediments. It is inferred that the sedimentation rates in the Bauer Deep are influenced by the proximity of the East Pacific Rise, It appears that sediments in the Bauer Deep are largely the product of hydrothermal processes on the East Pacific Rise, and that the precipitates are transported in suspension to the Bauer Deep. Authigenic precipitation of elements from sea water also occurs, having a stronger influence on the sediments as the precipitation of rise-crest material decreases away from the ridge. / Graduation date: 1974

Cyanobacteria are rich in biologically active secondary metabolites, many of which have potential application as anticancer or antimicrobial drugs or as useful probes in cell biology studies. A Jamaican isolate of the marine cyanobacterium, Lyngbya majuscula was the source of a novel antifungal and cytotoxic secondary metabolite, hectochlorin. The structure of hectochlorin suggested that it was derived from a hybid PKS/NRPS system. Unique features of hectochlorin such as the presence of a gem dichloro functionality and two 2,3-dihydroxy isovaleric acid prompted efforts to clone and characterize the gene cluster involved in hectochlorin biosynthesis. Initial attempts to isolate the hectochlorin biosynthetic gene cluster led to the identification of a mixed PKS/NRPS gene cluster, LMcryl, whose genetic architecture did not substantiate its involvement in the biosynthesis of hectochlorin. This gene cluster was designated as a cryptic gene cluster because a corresponding metabolite remains as yet unidentified. The expression of this gene cluster was successfully demonstrated using RT-PCR and these results form the basis for characterizing the metabolite using a novel interdisciplinary approach. A 38 kb region putatively involved in the biosynthesis of hectochlorin has also been isolated and characterized. The hct gene cluster consists of eight open reading frames (ORFs) and appears to be colinear with regard to hectochlorin biosynthesis. An unusual feature of this gene cluster includes the presence of a ketoreductase domain in an NRPS module and appears to be the first report of such an occurrence in a cyanobacterial secondary metabolite gene cluster. Other tailoring enzymes present in the gene cluster are two cytochrome P450 monooxygenases and a putative halogenase. The juxtaposition of two ORF's with identical modular organization suggests that this gene cluster may have resulted from a gene duplication event. Furthermore, biochemical characterization of two adenylation domains from this cluster strengthens its involvement in the biosynthesis of hectochlorin. / Graduation date: 2006

The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. / Graduation date: 1970

Observations were made of salinity, temperature, nitrate + nitrite, phosphate, silicate, total available nitrogen, and chlorophyll a in nine areas of the Alaskan Inside Passage during April of 1971. In general all properties indicated the water to be well mixed throughout this area. The conservative properties were particularly uniform. The greatest range in temperature from the surface to 200 m was only 1.1°C. The largest salinity range over the same depth was 2.0 ₀/₀₀ Spring phytoplankton blooms were just beginning to appear. Clarence Strait, in the southern part, presented the most evidence of biological activity. Values of chlorophyll a in this area were the highest observed (7.25 mg chl a/m³) outside of Auke Bay. This area also had the most density structure, probably due to stabilization brought on by warming. N:Si:P ratios for Clarence Strait indicate that silicate could become limiting in this area. The only other area, outside of Auke Bay, that had evidence (high chlorophyll a) of biological activity was Taku Inlet. The N:Si:P ratios for this area indicate that nitrate will probably be the limiting nutrient. Low oxygen values (2 ml/l) from the bottom of several deep basins indicate the possibility of anaerobic conditions developing as the water column stabilizes. Flow within the Inside Passage seems to be controlled by freshwater and saltwater inputs. Several major sources of both types of water are found. Tides and winds contribute to the circulation of the area but the mixing of saltwater and freshwater seems to be the predominant force. Local effects such as land runoff, glacial melt, input from hot springs and bottom topography are important in determining water conditions. Total available nitrogen may be a better indicator of photosynthesis than nitrate. TAN:P ratios tend to remain higher during photosynthesis than nitrate:P ratios. / Graduation date: 1972

In April of 1974, Oregon State University conducted a geophysical survey of the Orozco fracture zone, a Left-lateral transform fault which offsets the East Pacific Rise off the coast of Mexico near 15°N, 105°W. Magnetic, gravity, bathymetric, and seismic reflection data were collected during a four day period. This survey is combined with previous surveys by Oregon State University and other institutions to provide a geophysical interpretation of the Orozco fracture zone and the surrounding area and to develop a tectonic history of the northern Cocos plate. The Orozco fracture zone is characterized by a typical zone of seismicity and an offset in the magnetic anomaly pattern. There is, however, a conspicuous absence of a well defined topographic trough. This appears to be a result of the small age offset of the ridge crest, a reorientation of the fracture zone trend, and a possible southward migration of the fracture zone down the ridge axis. Three crustal and subcrustal cross sections over the Orozco fracture zone are constructed from the gravity data. One, across the active portion between the ridge offset, shows the active troughs to be underlain by a broad, low-density root extending two kilometers into the mantle. Two gravity cross sections across the East Pacific Rise show a thinning of oceanic layer 3 of nearly 2 kilometers at the rise crest and a corresponding 0.5 kilometer thickening of layer 2. A large magnetic anomaly of over 1300 gammas is found at the intersection of the Orozco fracture zone and the East Pacific Rise. A comparison with a very similar observation at the intersection of the Juan de Fuca ridge and the Blanco fracture zone in the northeast Pacific suggests that the East Pacific Rise is "leaking" into the fracture zone in this area. Many features have been observed on the northern Cocos plate which cannot be accounted for by present Pacific-Cocos motion the northeast strike of the eastern extension of the Orozco fracture zone, an apparent fanning of magnetic anomalies, and the northeast strike, as well as the origin, of the Tehuantepec ridge. Several possible schemes are examined to explain these observations and all but one are completely eliminated. The proposed explanation supposes a reorientation of the spreading center after a large change in the Pacific- Cocos pole of rotation resulting in the Zed pattern described by Menard and Atwater (1968). / Graduation date: 1976

A deep source-receiver seismic refraction experiment was conducted on the upper part of the Monterey Deep Sea Fan. The aim of this thesis is to construct the velocity structure of the upper Monterey Fan and to examine the lateral seismic velocity variations among the upper, middle and lower fan subunits. Using primary waves and whispering gallery phases (the multiply-reflected refraction waves), the sediment velocity structure was modeled by the tau-zeta travel time inversion process. The changes in velocity gradients with depth of the upper Monterey Fan are morphologically similar to that found on both the Central Bengal Fan and the Nicobar Fan, an abandoned lower fan of the Bengal Fan Complex. The velocity gradient of the upper Monterey Fan at depth, 0.59 s⁻¹ is significantly lower than both the middle Bengal Fan (0.68 s⁻¹) and the Nicobar Fan (0.81 s⁻¹). The upper fan subunit, which is closer to its sediment source, is characterized by higher porosities caused primarily by a higher sedimentation rate than the lower fan subunits. Since seismic velocity is inversely related to porosity, the upper fan subunit should have lower velocity gradients and seismic velocities than the other fan subunits. If porosity and velocity variations exist, then these variations can be used to constrain various models of deep sea fan formation. No definite conclusion can be drawn at this time due to a fault within 1 km of the Nicobar Fan site; however, a systematic velocity variation pattern of deep sea fans is revealed. Some portions of the Monterey Fan data contain refracted waves which have bottomed within the underlying acoustic basement structure. The entire velocity structure was solved by both the general and the "stripping" solving schemes. The results of basement structure show a velocity ranging from 3.4 to 5.8 km/s indicating that the uppermost part may be pre-existing continental rise sediments. / Graduation date: 1986

A multidisciplinary western Beaufort Sea Ecological Cruise (WEBSEC) was conducted from August 15 to September 20, 1971. During the cruise, one hundred ninety-nine 0.1 m² Smith-McIntyre grabs samples were taken at forty stations located on the continental shelf and slope of the western Beaufort Sea. The Gammaridean Amphipoda and Cumacea collected were sorted and identified. Each sample was analyzed for the number of species and specimens within those groups. The data for all samples at each station were pooled to obtain station data; these were analyzed for abundance, diversity at each station, and similarity between stations. Environmental parameters including sediment data, temperature, salinity and organic carbon content measured during the same cruise were also analyzed for each station. The diversity indices chosen were the Simpson index (SDI) and the Shannon-Wiener index (H'[subscript e]). The results obtained show a e relatively high diversity and animal density in the outer continental shelf, but low diversity values on the inner continental shelf and slope. The lowest SDI value obtained is 0.43 at 2572 m depth. The SDI values on the outer continental shelf are higher than 0.9 and compare well with values obtained in more temperate regions. The similarity between stations is low, and the percentage of rare species found is high. This indicates a patchy distribution of the Amphipoda and Cumacea fauna. The variability of the processes affecting the benthic environment of the western Beaufort Sea suggest that more intensive and seasonal studies are necessary in order to understand the seasonal as well as the annual variation of the infauna of the western Beaufort Sea. / Graduation date: 1976

Graduation date: 2005

Examination of polished sections of manganese micronodules from metalliferous sediments from the Bauer Deep reveals sequences of ferromanganese deposition which are consistent for micronodules from a single sediment sample and imply a common depositional history for members of such assemblages. The relatively simple 'stratigraphy' of manganese micronodules, as compared to macronodules, makes stratigraphic correlation of depositional histories easier and more conclusive for micronodules than macronodules. Quantitative microprobe analysis and X-ray mircodiffraction patterns indicate that the major authigenic silicate component of metalliferous sediment is an iron- and magnesium-rich, low-aluminum nontronite. Microprobe and X-ray microdiffraction analyses of manganese micronodules establish todorokite as the predominant crystalline component. Comparison of the distributions of lanthanum, cerium, and samarium in micronodules and phosphatic fish debris indicates that bulk sediment REE distribution is determined by the relative abundances of cerium-enriched micronodules and cerium-depleted biogenic phosphate. / Graduation date: 1974

This thesis details my investigations of marine cyanobacterial natural products that resulted in the discovery of thirteen new secondary metabolites, the isolation of over fifteen previously reported metabolites and the biosynthetic investigation of two additional cyanobacterial compounds. Two novel lipopeptides were identified from a Lyngbya majuscula and Schizothrix sp. assemblage collected in the Fiji Islands. Somamide A is a depsipeptide consisting of a hexanoate moiety extended by seven amino acids, including two nonstandard units characteristic of cyanobacterial peptides. In contrast, somocystinamide A is a unique linear disulfide dimer displaying potent cytotoxicity against a mammalian neuroblastoma cell line. The organic extract from a Puerto Rican L. majuscula proved remarkably rich in chemistry, producing twelve known compounds as well as four new secondary metabolites. Among these new isolates were the novel sodium channel blocker antillatoxin B, a new chlorinated quinoline derivative and the new ��-pyrone malyngamide T. A collection of L. majuscula from Antany Mora, Madagascar, led to the isolation of the previously reported antineoplastic agent dolastatin 16 and the discovery of a new series of lipopeptides, the antanapeptins. These new molecules are characterized by the presence of the unique ��-hydroxy acid 3-hydroxy-2-methyloctynoate, or its reduced double- or single-bond equivalent. Wewakazole is a novel cyclic dodecapeptide isolated from a Papua New Guinea collection of L. majuscula. This large molecule contains both a methyloxazole and two oxazoles, residues rarely observed in marine cyanobacterial metabolites. Extensive utilization of 1D and 2D NMR techniques were required to elucidate the structure of this distinctive peptide. Biosynthetic investigations of two halogenated cytotoxins were also conducted on a cultured L. majuscula strain originally isolated from Hector Bay, Jamaica. Stable isotope feeding experiments demonstrated that both jamaicamide A and hectochlorin derive from mixed PKS and NRPS biosynthetic origins but are comprised of primary precursors unique to each molecule. / Graduation date: 2003