ALBERT

Description: This report includes discussions of elastic and viscoelastic models for water-saturated porous media, and measurements and computations of elastic constants including compressibility, incompressibility (bulk modulus), rigidity (shear modulus), Lamé's constant, Poisson's ratio, density, and compressional- and shear-wave velocity. The sediments involved are from three major physiographic provinces in the North Pacific and adjacent areas: continental terrace (shelf and slope), abyssal plain (turbidite), and abyssal hill (pelagic). It is concluded that for small stresses (such as from a sound wave), water-saturated sediments respond elastically, and that the elastic equations of the Hookean model can be used to compute unmeasured elastic constants. However, to account for wave attenuation, the favored model is ‘nearly elastic,’ or linear viscoelastic. In this model the rigidity modulus μ and Lamé's constant λ in the equations of elasticity, are replaced by complex Lamé constants (μ + iμ′) and (λ + iλ′), which are independent of frequency; μ and λ represent elastic response (as in the Hookean model), and iμ′ and iλ′ represent damping of wave energy. This model implies that wave velocities and the specific dissipation function 1/Q are independent of frequency, and attenuation in decibels per unit length varies linearly with frequency in the range from a few hertz to the megahertz range. The components of the water-mineral system bulk modulus are porosity, the bulk modulus of pore water, an aggregate bulk modulus of mineral grains, and a bulk modulus of the structure, or frame, formed by the mineral grains. Good values of these components are available in the literature, except for the frame bulk modulus. A relationship between porosity and dynamic frame bulk modulus was established that allowed computation of a system bulk modulus that was used with measured values of density and compressional-wave velocity to compute other elastic constants. Some average laboratory values for common sediment types are given. The underlying methods of computation should apply to any water-saturated sediment. If this is so, values given in this paper predict elastic constants for the major sediment types.

Description: Four marine Cretaceous samples collected from the Agulhas Bank are discussed and their ostracodal assemblages described. Two of the samples are considered to be Lower Cretaceous, and the others Lower-Middle Senonian and Maastrichtian in age. Two new genera, twelve new species, and one new subspecies are described. Details of the foraminiferal assemblages are also given.

Description: Three species of Foraminifera, which were ususally regarded as members of the Ammonia beccarii (L.)-group or closely related, are investigated. The material comes mainly from the lagoon of Cochin and from the shelf off Cochin (SW-India), Malabarcoast). Sections and Stereoscan-microphotographs revealed considerable differences in the internal structure (double or simple septae, different shape of the tooth-plates, areal or interiomarginal situation of the septal apertures). This leads to the conclusion, that only one species (Rotalia beccarii var. sobrina SHUPACK 1934) is a true Ammonia. Rotalia beccarii var. tepida CUSHMAN 1926 should be put to the genus Discorbis, Rotalia pauciloculata PHLEGER & PARKER 1951 is regarded as a species of Pseudoeponides. Some ecological observations are added.

Description: Shipworms or Teredinidae may be dispersed either as adults in floating wooden objects or as pelagic larvae drifting near the sea surface. Five shipworm species, i.e., half of those having an amphi-Atlantic geographical distribution, are known also to have pelagic phytoplanktotrophic larvae which can be carried by ocean currents. From a series of 742 plankton samples taken from throughout the temperate and tropical North Atlantic Ocean, it can be shown that shipworm larvae are not uncommon in the open sea. Teredinid veligers were found in 19% of all samples taken. One species of larvae, identical in all details to that described by Rancurel (1965), is particularly prevalent and is tentatively identified as Teredora malleolus (Turton). A definitive identification will be possible only after the pelagic larvae of the other Atlantic species are known. The larvae of Teredora malleolus are found throughout the North Atlantic Gyre and the adjacent temperate and tropical seas, and from scattered records in the South Equatorial Current. Larvae of other unidentified Teredinidae species were also found. The distance that larvae may be transported depends upon the length of pelagic larval development and the velocity of the currents. From the known current velocities it can be shown that, even in a few weeks, larvae may be dispersed many hundreds of kilometers. The geographical distribution of shipworm larvae suggests that they are carried along the coasts of continents and even across ocean basins, and that this dispersal must be an important factor in the geographical distribution of the adult forms and in the maintenance of genetic continuity between populations otherwise isolated from one another.

Description: This report includes discussions of elastic and viscoelastic models for water‐saturated porous media, and measurements and computations of elastic constants including compressibility, incompressibility (bulk modulus), rigidity (shear modulus), Lamé's constant, Poisson's ratio, density, and compressional‐ and shear‐wave velocity. The sediments involved are from three major physiographic provinces in the North Pacific and adjacent areas: continental terrace (shelf and slope), abyssal plain (turbidite), and abyssal hill (pelagic). It is concluded that for small stresses (such as from a sound wave), water‐saturated sediments respond elastically, and that the elastic equations of the Hookean model can be used to compute unmeasured elastic constants. However, to account for wave attenuation, the favored model is ‘nearly elastic,’ or linear viscoelastic. In this model the rigidity modulus μ and Lamé's constant λ in the equations of elasticity, are replaced by complex Lamé constants (μ + iμ′) and (λ + iλ′), which are independent of frequency; μ and λ represent elastic response (as in the Hookean model), and iμ′ and iλ′ represent damping of wave energy. This model implies that wave velocities and the specific dissipation function 1/Q are independent of frequency, and attenuation in decibels per unit length varies linearly with frequency in the range from a few hertz to the megahertz range. The components of the water‐mineral system bulk modulus are porosity, the bulk modulus of pore water, an aggregate bulk modulus of mineral grains, and a bulk modulus of the structure, or frame, formed by the mineral grains. Good values of these components are available in the literature, except for the frame bulk modulus. A relationship between porosity and dynamic frame bulk modulus was established that allowed computation of a system bulk modulus that was used with measured values of density and compressional‐wave velocity to compute other elastic constants. Some average laboratory values for common sediment types are given. The underlying methods of computation should apply to any water‐saturated sediment. If this is so, values given in this paper predict elastic constants for the major sediment types.

Description: A technique for rearing the loliginid squids Sepioteuthis sepioidea and Doryteuthis plei is reported. Specimens of the former were reared from eggs to sexually mature adults, and maintained for a maximum of 146 days; adult D. plei were maintained for 38 days. Choice and quantity of food was most important for the survival of all sizes, particularly young squid. Newly hatched specimens thrived on Mysidium columbiae. Both species fed at a rate of 30 to 60% of their body weight daily; starvation occurred when intake fell below 10 to 15%. Food conversion efficiency averaged between 10 to 20%. Growth was rapid and steady. S. sepioidea grew to a maximum of 105 mm and 77 g in less than 5 months; D. plei grew an estimated 20 mm/month. Experimental data indicate a lethal minimum salinity for both species at about 27‰. Lethal minimum and maximum temperatures for young S. sepioidea are 17.5° to 18.0°C, and 32.5° to 33.0°C, respectively. Young consume 0.64μl O2/mg wet weight/h. Opaque tanks, with a semi-natural bottom substrate and special ultra-violet (UV) illumination, are advantageous for rearing and maintenance.

Description: Analyses of bottom trawl samples and feeding experiments in the laboratory revealed a reproduction period ranging from late March to early August in Eledone cirrosa of the Catalonian Sea (Western Mediterranean). The embryonic development, studied for the first time on eggs laid in the laboratory, shows no basic difference from that of other Octopodiae. The newly hatched animals are planctonic; Morphologically, this feature is expressed by a relatively small arm-length.

Description: Five species of Sepiola were reared in the laboratory from egg to adult size. Spawning was achieved in 3 species of Sepiola afteer 5 to 7 months. The growth rate of the species reared did not depend upon temperature, which ranged from 12,5° to 20°C. A fairly constant size increase (2,5mm mantle length/month) was observed in Sepiola during the 5 months after hatching. In Sepietta, the same growth rate was observed until the fourth month after hatching, when it increased to the rate of 5 mm mantle length/month.

Description: Continuous Bathysonde profiles of temperature versus pressure were used to follow the depths of isotherms at a deep sea anchor station northwest of the Great Meteor Seamount (30 ° N, 28 ° W) from 19th to 27th of April 1967. Assuming temperature to be a conservative parameter, vertical velocities can be computed from the vertical displacements of isotherms, according to equations (1) or (7), respectively. Several advective terms of higher order, however, seem to be large compared to lower order terms (see equ. (7) and table 1). In addition, advective velocities are only known approximately for the period of the measurements. Therefore the total vertical velocity for each depth could not be determined. However, it can be assumed that vertical velocities of semi-diurnal tidal period are large compared, to vertical motions of other frequencies (see fig. 2). The vertical velocity of the semi-diurnal tidal motion can therefore be computed from equ. (10) (table 2). A subsequent approximation of the observed distribution of the vertical velocity component by eigenfunctions reveals a reasonable description of the baroclinic semi-diurnal tide by internal gravity wave modes of the order 1-4 (see fig. 5).

Description: Based on measurements during the "Atlantic Seamount Cruises 1967" with the German R. V. Meteor, (see Cwss et al., 1969; HORN et al., 1971), the fluctuations of temperature in the upper 275 meters are investigated. The analysis of 67 time-series yields the following : 1. Within the period range from 124 hours to 10 minutes fundamental oscillations and their harmonics occur permanently with relatively high amplitudes. These oscillations could be attributed to the diurnal (K1) and semidiurnal (M2) surface- and internal tidal waves as well as to their harmonics. It ought to be mentioned that in the surveyed area the K1-tide and the inertial wave have the same periods and could not be separated by spectrum analysis. 2. Interactions between the K1- or M2-waves and their harmonics by single superposition are shown in the observed periods. These two facts possibly can be explained by the perturbative influence of the Great Meteor Seamount on long wave motions. 3. Special investigations of the short period range lead to significant oscillations with periods between 15 and 40 minutes, which correspond to the Brunt-Väisälä-frequency calculated from the mean density distribution. 4. The diurnal variation of tempernture at the sea surface has a mean amplitude of 0.3 °C and a penetration depth of about 55 m. The mean vertical eddy conductivity amounts to 260 g cm-1 sec-1.