Showing papers by "Woods Hole Oceanographic Institution published in 1968"

Rises, trenches, great faults, and crustal blocks

Abstract: The transform fault concept is extended to a spherical surface. The earth's surface is considered to be made of a number of rigid crustal blocks. It is assumed that each block is bounded by rises (where new surface is formed), trenches or young fold mountains (where surface is being destroyed), and great faults, and that there is no stretching, folding, or distortion of any kind within a given block. On a spherical surface, the motion of one block (over the mantle) relative to another block may then be described by a rotation of one block relative to the other block. This rotation requires three parameters, two to locate the pole of relative rotation and one to specify the magnitude of the angular velocity. If two adjacent blocks have as common boundaries a number of great faults, all of these faults must lie on ‘circles of latitude’ about the pole of relative rotation. The velocity of one block relative to the other must vary along their common boundary; this velocity would have a maximum at the ‘equator’ and would vanish at a pole of relative rotation. The motion of Africa relative to South America is a case for which enough data are available to critically test this hypothesis. The many offsets on the mid-Atlantic ridge appear to be compatible with a pole of relative rotation at 62°N (±5°), 36°W (±2°). The velocity pattern predicted by this choice of pole roughly agrees with the spreading velocities determined from magnetic anomalies. The motion of the Pacific block relative to North America is also examined. The strike of faults from the Gulf of California to Alaska and the angles inferred from earthquake mechanism solutions both imply a pole of relative rotation at 53°N (±3°), 53°W (±5°). The spreading of the Pacific-Antarctic ridge shows the best agreement with this hypothesis. The Antarctic block is found to be moving relative to the Pacific block about a pole at 71°S (±2°), 118°E (±5°) with a maximum spreading rate of 5.7 (±0.2) cm/yr. An estimate of the motion of the Antarctic block relative to Africa is made by assuming closure of the Africa-America-Pacific-Antarctica-Africa circuit and summing the three angular velocity vectors for the cases above.

Sea Levels during the Past 35,000 Years.

Abstract: A sea-level curve of the past 35,000 years for the Atlantic continental shelf of the United States is based on more than 80 radiocarbon dates, 15 of which are older than 15,000 years. Materials include shallow-water mollusks, oolites, coralline algae, beachrock, and salt-marsh peat. Sea level 30,000 to 35,000 years ago was near the present one. Subsequent glacier growth lowered sea level to about -130 meters 16,000 years ago. Holocene transgression probably began about 14,000 years ago, and continued rapidly to about 7000 years ago. Dates from most shelves of the world agree with this curve, suggesting that it is approximately the eustatic curve for the period.

Milankovitch Hypothesis Supported by Precise Dating of Coral Reefs and Deep-Sea Sediments

Abstract: Barbados provides a possibly unique opportunity for reconstruction of the times and elevations of late-Pleistocene high stands of the sea. The island appears to be rising from the sea at a uniform rate that is fast enough to separate in elevation coral-reef tracts formed at successive high stands of the sea. Unaltered coral found in the lower terraces enables high-precision Th(230): U(234) and Pa(231): U(235) dating. Three distinct high stands of the sea are found about 122,000, 103,000, and 82,000 years ago. New Pa(231) and Th(230) dates from a deep-sea core also indicate that Ericson's W-X cold-to-warm climatic change occurred close to 126,000 years ago. These data show a parallelism over the last 150,000 years between changes in Earth's climate and changes in the summer insolation predicted from cycles in the tilt and precession of Earth's axis.

Respiration and nitrogen excretion by some marine zooplankton in relation to their life cycles

Abstract: Rates of respiration and nitrogen excretion have been measured for freshly caught Calanus finmarchicus (Gunnerus), Calanus hyperboreus (Krayer), Metridia longa (Lubbock) and Pareuchaeta norvegica (Boeck), from the Gulf of Maine at all seasons. The dry weight, total (Kjeldahl) nitrogen, and fat were also determined for the same animals. Seasonal variation in weight-corrected respiration and nitrogen excretion followed a similar pattern for all four species, being high in the spring and decreasing gradually through summer and fall to a winter minimum. However, the relative proportions of oxygen utilized to nitrogen excreted were different from season to season for each species. In Calanus spp., O: N ratios by atoms were highest in May, immediately after the spring bloom of phytoplankton, when the animals were rich in fat. With C. hyperboreus the ratio then declined gradually through summer and fall to a low point just before the spring bloom (March and April) when populations contained the least amount of fat; but with C. finmarchicus the ratio fell much more rapidly, remaining near 17 through summer and fall and increasing again with the production of the overwintering generation. In Metridia and Pareuchaeta the O:N ratios did not show as much seasonal variation, although there was a pronounced increase for Metridia just after the spring bloom. Both species usually had higher respiration and excretion rates and lower O:N ratios compared with Calanus spp.

Relict Sediments on Continental Shelves of World

Abstract: The sediments that were deposited on the continental shelves during and immediately after the latest glacial stage of the Pleistocene Epoch are unrelated to their present environments. The rise of sea level during the past 19,000 yrs has caused previously deposited subaerial, lacustrine, and paludal sediments to become submerged in shallow-marine waters, and later to become deeply submerged. Land-laid or shallow-marine sediments which occur in deep water, such as those near the seaward edge of the continental shelf, are properly termed "relict." At present, the sediments exposed atop about 70 percent of the area of the continental shelves of the world can be identified as relict. Eventually, new detrital sediments that are contributed to the ocean by streams or shore eros on should prograde entirely across the continental shelf and bury the relict sediments. This burial should be hastened if the rise of sea level remains as slow as it has been during the past few thousand years; nevertheless, several tens of thousands of years probably will be required before most of the relict sediment becomes buried.

Dissolved Organic Carbon from Deep Waters resists Microbial Oxidation

Abstract: OCEANS contain a large absolute amount of organic material in solution. The origin, fate and involvement in biogeochemical processes of this large, but extremely dilute, pool of organic compounds is an enigma to those studying the life and chemistry of the oceans. Recent studies by several workers1–7 have shown that the dissolved organic carbon (DOC) content of deep water is relatively constant over a wide range of depths and throughout many regions of the world's oceans. The DOC content averages about 0.60 mg/l. and does not decrease significantly with depth from 400 m to 6,000 m (refs. 2 and 4), nor does the DOC increase in deep waters below highly productive regions such as along the coast of Peru2,4. The range of reported values is from 0.40 to 0.70 mg/l.

Characterization of photosynthetic sulfur bacteria causing red water in lake faro (messina, sicily)1

Abstract: The meromictic saline Lake Faro (Messina, Sicily) contains a layer of brownish-red water at the interface between hypo- and epilimnion, the depth of which varies between 8 and 13 m. The photosynthetic sulfur bacteria that cause this phenomenon were isolated and described. The predominant organism of the red water is the brown photolithotropic bacterium Chlorobium, phaeobacteroides Pfennig (Chlorobacteriaceae). In addition, a small, violet Chromatium species (Thiorhodaceae) was isolated, which had been observed in smaller numbers in the red layer. Although the Chromatium strain is motile and able to use a considerable variety of organic carbon compounds besides bicarbonate, in the natural environment of the lake the brown Chlorobium finds more advantageous growth conditions; it is suggested that its brown carotenoids allow more effective use of the penetrating wavelengths of daylight.

Dispersal of Larvae by Equatorial Ocean Currents and its Importance to the Zoogeography of Shoal-water Tropical Species

Abstract: Dispersal of Larvae by Equatorial Ocean Currents and its Importance to the Zoogeography of Shoal-water Tropical Species

Fine Structure of Ectothiorhodospira mobilis Pelsh

Abstract: The cell wall structure, arrangement of photosynthetic membranes, and the attachment of flagella of Ectothiorhodospira mobilis strain 8112 were examined by using freeze-etching and conventional electron microscopic techniques. The outer coat of the multilayered cell wall is comprised of 50 A repeating subunits, arranged in a regular array. The photosynthetic membranes, which originate from and are attached to the plasma membrane, are arranged in a more complex pattern than previously seen in other bacteria. The tuft of flagella in E. mobilis is inserted into a polar organelle. The relationship of this organelle to the polar membrane and the mechanism of attachment of the flagella to the polar organelle is discussed.

The occurrence and role of glucose in seawater1

Abstract: Glucose in the Atlantic was measured along a transoceanic section by two independent techniques. The concentrations varied from a high of 10−8 m to values below 10−8 m. The highest concentrations occurred within 480 km of Bermuda although significant concentrations were also associated with the area of upwelling off Senegal. Densities of phytoplankton exhibited a positive correlation with the glucose concentration. Experiments on glucose uptake by the natural microbial population showed the common occurrence of glucose users in the sea but also pointed out the need for enzymatic adaptation whenever glucose was absent or present below a critical concentration.

On the ATP generation by Chromatium in darkness.

Abstract: In Chromatium strain 6412 storage carbohydrate synthesized in the light, gradually disappeared in the dark. Simultaneously, poly-β-hydroxybutyric acid (PHB) was produced, CO2 was released and intracellular elemental sulfur was reduced to sulfide. Expressed on a molar base, the ratio between storage carbohydrate monomer (as glucose) consumed, sulfur reduced, PHB monomer produced, and sulfide released was approximately 1 : 3 : 1 : 3. This indicates that sulfur acts electron acceptor in the conversion of storage carbohydrate to PHB. Assuming that in the dark storage carbohydrate is broken down to pyruvate via the Embden-Meyerhoff pathway, whereafter PHB is synthesized from pyruvate via acetyl-CoA and acetoacetyl-CoA, the conversion of storage carbohydrate to PHB results in a net gain of 3 ATP per glycosyl unit converted. Since Thiorhodaceae are photolithotrophs, these processes would provide the organisms with maintenance energy during dark periods. They also explain motility of Chromatium in the dark.

Surface Characteristics of Penicillium Conidia

Abstract: SUMMARYThe surface structures of 10 species of Penicillium conidia were studied and compared using the freeze-etching technique. The conidia of all species studied were shown to have an outer layer...

Ectothiorhodospira mobilis Pelsh, a Photosynthetic Sulfur Bacterium Depositing Sulfur Outside the Cells

Abstract: From salt flats on the Galapagos Islands, two strains of a red photosynthetic bacterium were isolated and identified as Ectothiorhodospira mobilis, an organism first described by Pelsh in 1937. The cells are curved in a short spiral, 0.7 to 1.0 μ wide and 2.0 to 4.8 μ long. They are motile by a polar tuft of flagella. Cells contain several large stacks of lamellar membranes, carrying the pigments bacteriochlorophyll a and carotenoids of the spirillo xanthin series. Cell division occurs by binary fission, not budding. The organism is strictly anaerobic and obligately photosynthetic. Its ability to grow well with sulfide, sulfur, thiosulfate, or sulfite as photosynthetic H donors puts it taxonomically in the Thiorhodaceae. During growth with sulfide, elementary sulfur is deposited outside the cells in the medium and disappears during further growth. A limited number of organic carbon compounds can be utilized as hydrogen donors in place of inorganic sulfur compounds. Under these conditions, sulfate can serve as the sulfur source. The enzymes catalase and hydrogenase are present. The newly isolated strains require vitamin B12. They also require a salinity of 2 to 3% NaCl, but they are not extreme halophiles. The organism is not identical with any of the species listed in Bergey's Manual.

Radiance of Sea and Sky in the Infrared Window 800-1200 cm-1

Abstract: Expressions are obtained for the infrared radiance of a rough ocean surface by a method closely following that of Cox and Munk. For normal viewing, average radiance is found to be practically independent of roughness, but for oblique viewing blackness increases with roughness. Shadowing is treated in a simple approximate manner and estimates of surface radiance are made for glancing angles of viewing: an infrared horizon is predicted. The theoretical results, which are closely substantiated by observations, reveal the dish-shaped character of the ocean and indeed of any rough surface.

Fine structure of the mesosome and nucleoid in frozen-etched Bacillus subtilis.

Abstract: An electron microscopical investigation ofBacillus subtilis prepared by freeze-etching revealed the fine structural changes that occur in the cell prior to spore formation. The initiation of growth from lyophilized cells was characterized by the appearance of numerous vesicular structures embedded in and attached to the plasma membrane. As growth continued, the number of vesicular structures decreased and lamellar membrane structures began to appear. Prior to spore formation, a fine, fibrillar material was found in the central portion of the cell and was believed to be the DNA.

Ceratoscopelus maderensis: peculiar sound-scattering layer identified with this myctophid fish.

Abstract: A sound-scattering layer, composed of discrete hyperbolic echosequences and apparently restricted to the Slope Water region of the western North Atlantic, has been identified from the Deep Submergence Research Vehicle Alvin with schools of the meyctophid fish Ceratoscopelus maderensis. By diving into the layer and using Alvin9s echo-ranging sonar, we approached and visually identified the sound scatterers. The number of echo sequences observed with the surface echo-soutnder (1/23.76 x 10 5 cubic meters of water) checked roughly with the number of sonar targets observed from the submarine (1/7.45 x 105 cubic meters). The fish schools appeared to be 5 to 10 meters thick, 10 to 100 meters in diameter, and on centers 100 to 200 meters apart. Density within schools was estimated at 10 to 15 fish per cubic meter.

On slow transverse flow past obstacles in a rapidly rotating fluid

Abstract: This paper describes an experimental and theoretical study of the complicated disturbance (Taylor column) due to the slow relative motion between a spherical, or short cylindrical, rigid object and an incompressible fluid of low viscosity in which the object is immersed, when the motion of the object is that of steady revolution with angular speed Ω rad/see about an axis (the Z-axis) whose perpendicular distance from the centre of the object, , is much greater than a typical linear dimension of the object, L, and the undisturbed fluid motion is one of steady rotation about the same axis with angular speed (Ω+Uϑ/R) and zero relative vorticity (i.e. d(Uϑ R)/dR = 0). It extends earlier experimental work on Taylor columns to systems of sufficiently large axial dimensions for Z variations in the disturbance pattern to be perceptible. Over the ranges of Rossby and Ekman numbers (based on L) covered by the experiments, namely e = 1·89 × 10−3 to 2·36 ×10−1 and γ = 1·30 × 10−3 to 2·03 × 10−2 respectively, the axis of the Taylor column is found to trail in the downstream direction at a small angle ϕ = tan−1 (Ke) to the line parallel to the Z-axis through the centre of the object, where K = (1·54 ± 0·04) for a sphere. The variation with Z of the amplitude of the disturbance is roughly linear and the scale-length of this variation, Zc, is close to L/γ¼ over the limited range of γ covered by the experiments.The experimental value of K is remarkably close to the theoretical value derived by Prof. Lighthill in the appendix, where he applies his general linear theory of waves generated in a dispersive system by travelling forcing effects to the problem of describing a Taylor column at large distances from the moving object when the fluid is inviscid and unbounded.

Structure of Continental Margin off Gulf Coast of United States

Abstract: Continuous seismic-reflection profiles were recorded along 15 lines across the continental margin of the Gulf of Mexico. The steep slopes off Florida and Yucatan (Florida and Campeche escarpments) appear to have been formed by construction of coral or algal reefs during the Cretaceous Period. The adjacent upper continental slope and continental shelf were formed by prograding and upbuilding of largely calcareous sediments after the death of the Cretaceous reef-building organisms. Off Louisiana, Texas, and part of Mexico the upper continental slope and the continental shelf were formed by progradation and upbuilding of terrigenous sediment contributed largely by the Mississippi River during the Tertiary Period. These sediments buried deeply much of the Early Cretaceous ree . Considerable alteration of the general structure off Louisiana and Texas resulted from contemporaneous intrusion of salt diapirs. Sediments in the basins between the diapirs were derived partly from the tops of the nearby salt intrusives. The Sigsbee escarpment at the seaward edge of the sedimentary prism off Louisiana and Texas is bordered by a broad ridge of diapirs, to which it may owe its origin. Although diapiric structures are best known north of the Sigsbee escarpment, others are present on the south, at the center of the Gulf basin, and as far south as Golfo de Campeche. During Early Cretaceous time the reef once almost surrounded the Gulf of Mexico, probably leaving only one narrow connection with the open ocean at the southeast. The narrow opening and the low relative sea level, indicated by reef structure and calcareous algae nearly 3,000 m below present sea level, suggest that water circulation was restricted during Early Cretaceous time. If it had been somewhat more restricted earlier, conditions could have been suitable for the widespread deposition of Late Triassic to Middle Jurassic salt that later fed the diapiric structures.

Genesis and Evolution of Water Masses

Abstract: The main water masses of the oceans are described as they exist at the present time It is postulated that at the height of the Wisconsin glacial period the mean salinity of the oceans was 357‰, one part per thousand more saline than it is now The evolution and eventual dissipation of the Wisconsin bottom water mass is discussed together with the possible effect of this water mass on pelagic sediments

A sediment coring device of 21‐cm diameter with sphincter core retainer1

Abstract: A 21-cm-ID gravity corer of a new design was developed to provide large cross section core samples for analysis of fallout radionuclides in sediments of Crater Lake, Ore. The study of vertical profiles of the concentration of fallout radionuclides (which have been available for sedimentation only since the early 1950's in most places) also demands efficient sampling of the top-most layers of sediment and their recovery in situ. Some evidence from studies of more conventionally collected cores indicates that these upper layers are commonly lost, either by washout at the top of the core tube or by being swept away from the point of impact by the shock wave of rapidly falling corers. Another requirement is efficient retention of a variety of sediment types, ranging from very soft muds to coarse, sharp sands; loss of water through the usual core-retaining devices commonly flushes out such samples. The new coring device, combining large diameter with positive, watertight closing of both bottom and top of the core tube at the time of pullout, meets all these requirements.