Cytochrome P450 differences in normal and imposex-affected female whelk Buccinum undatum from the open North Sea

Normal and imposex-affected female Buccinum undatum were sampled from the open North Sea at three locations, one with low, and two with high shipping densities. Cytochrome P450 components and P450 aromatase activity were determined in the microsomal fractions isolated from pooled digestive gland/gonads. Cytochrome P450 aromatase activity was significantly higher (P < 0.05) in normal females collected in the low shipping density area (1,325 +/- 295 fmol/h/mg protein) than levels from imposex animals from a high shipping density area (620 +/- 287 fmol/h/mg protein). A negative correlation was found between aromatase activity and organotin body burden (r = -0.99). Levels of CYP450, cytochrome b5 and NADPH cytochrome c reductase activity did not show differences among groups. This is the first field evidence of depressed aromatase activity in imposex affected females, although additional research under laboratory controlled conditions is required to fully understand the mechanisms underlying the development of imposex in this species.     

Seasonal variations of water system distribution and flow patterns in the southern sea area of Hokkaido,Japan

Hydrographic data and composite current velocity data (ADCP and GEK) were used to examine the seasonal variations of upper-ocean flow in the southern sea area of Hokkaido, which includes the “off-Doto” and “Hidaka Bay” areas separated by Cape Erimo. During the heating season (April–September), the outflow of the Tsugaru Warm Current (TWC) from the Tsugaru Strait first extends north-eastward, and then one branch of TWC turns to the west along the shelf slope after it approaches the Hidaka Shelf. The main flow of TWC evolves continuously, extending eastward as far as the area off Cape Erimo. In the late cooling season (January–March), part of the Oyashio enters Hidaka Bay along the shallower part of the shelf slope through the area off Cape Erimo, replacing almost all of the TWC water, and hence the TWC devolves. It is suggested that the bottom-controlled barotropic flow of the Oyashio, which may be caused by the small density difference between the Oyashio and the TWC waters and the southward migration of main front of TWC, permits the Oyashio water to intrude along the Hidaka shelf slope.     

Dynamic response of the leg of a tension leg platform subjected to an axial, suddenly applied load at one end

This paper deals with the solution of the problem of the dynamic response of the leg of a tension leg platform subjected to an axial, suddenly applied load at one end, considering a highly simplified model but taking into account several complicating factors. The problem is solved by means of a non-harmonic Fourier expansion in terms of eigenfunctions obtained from a non-regular Sturm-Liouville system.     

Mapping sediment acoustic impedance using remote sensing acoustic techniques in a shallow-water carbonate environment

 Real-time trackline plots of surficial sediment acoustic impedance delineate several sedimentary facies off Garden Key in the Dry Tortugas. The sea floor within a 6×6 km surveyed area consists of carbonate muds (silts), sands and shell, rock, and live corals. The 4-kHz acoustic data supports this finding by providing a pictographic representation of the distribution and structure of several sediment facies types. Plotting the gridded acoustic data with commercial mapping software (Surfer) provides a three-dimensional (3D) perspective of the bottom topography with a color contour map of surficial sediment impedance (upper 0.4 m) draped over the 3D surface.     

On the vertical structure of temperature anomalies in the North Atlantic

The expansion of the temperature anomaly field in the North Atlantic is considered using natural orthogonal functions of depth. It is shown that the first few components of this expansion describe the field both at the surface and in the upper 1000 m layer accurately enough. The relation between the water temperature anomaly at some levels and the above components is estimated for various regions of the ocean.Translated by Mikhail M. Trufanov.     

Proper movement of a current meter mounted on a suspended drift station

In situ observations of the movement of a current meter attached to a long cable system of a drifting research vessel are discussed. A method is suggested which allows the cable configuration to be restored using measurement data on tangent orientation with respect to the given points. The compiled data indicate that the elements of the cable system shift by dozens of metres with a speed of the order of tens of cm per second. These shifts account for about 90% of the estimated value of current velocity energy pulsations in the frequency band corresponding to the proper frequency oscillations of the current meter and of the vessel's roll and-and-pitch motions.Translated by V. Puchkin.     

Seasonal changes in coccolithophore densities in the Southern California Bight during 1991–1992

Seasonal changes in coccolithophore cell densities in the San Pedro Basin, Southern California Bight, were investigated for the period October 1991 to September 1992. Coccolitho phore cell densities ranged from 6.3 × 10⁴ coccospheres per liter in March 1992 to 0 cells per liter in November 1991. High coccolithophore concentrations occurred in late winter and spring, and low densities occurred in the summer and fall. The high coccolithophore densities during spring 1992 were associated with unusually low surface nutrient concentrations and a lack of upwelling, suggesting that the high densities were not part of a typical spring phytoplankton bloom in this region. We propose that the suppression of upwelling during spring 1992 may have been related to the prevailing ENSO conditions. Emiliania huxleyi type A dominated the total coccolithophore population throughout the year, Umbilicosphaera sibogae var. sibogae being the second most important contributor to the coccolithophore assemblages.