Feature modeling approach to simulating Loop Current Frontal Eddies

Loop Current Frontal Eddies (LCFE) in the Gulf of Mexico are simulated with a regional configuration of the Princeton Ocean Model using a feature-oriented initialization technique. The initialization procedure is based on a prior investigation of stability characteristics of the Loop Current (LC). Zonal channel experiments conducted with a multi-layer intermediate equations model allowed to identify conditions necessary for formation and growth of frontal eddies. The simulations were able to reproduce key features of LCFE-topography interaction in the DeSoto Canyon region observed during the “Eddy Intrusion” study.     

Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

A numerical experiment on the calculation of the tropical Atlantic circulation in 1982–1983, with the real wind considered

This paper discusses the results obtained through numerical modelling of the annual course of circulation and thermohaline field evolution in the tropical Atlantic under the impact of real wind forcing (from March 1982 to March 1983) and compares them with the calculation of seasonal variability induced by the climatic wind. Changes in the pattern of the equatorial currents and related temperature fields induced by the specific peculiarities in the wind field are analysed.Translated by Vladimir A. Puchkin.     

Accommodating ecotourism in multiple use planning of coastal and marine protected areas

Coastal and marine areas the world over provide food, transportation, recreation, and energy resources to increasing numbers of people each year. As demands for these resources rise, the potential for user conflicts is radically heightened. This situation can be avoided or counteracted by instigating proactive multiple use planning. Multiple use zoning plans can only exist in a concrete management framework: marine and coastal protected areas provide just such a foundation. Nature-based or ecotourism can be encouraged in coastal protected areas aimed at achieving sustainability. Well-planned tourism provides economic and political incentives for management and for conservation, and may bring additional benefits to local communities and regional economies. Examples where nature-based tourism has been or is becoming successfully integrated into multiple use planning can be found in Quintana Roo, Mexico; the Lesser Antilles; and Australia, among other areas.     

On the origin of glauconitic and chamositic granules

Glauconitic minerals range from green smectite to 10Å glauconite, occur mainly in peloids (most of which were fecal pellets), and apparently were produced largely by neoformation replacing several kinds of substrate. Chamositic minerals, berthierine and chamosite, occur in Recent and ancient peloids, but mostly in ancient ooids, and they developed by alteration of a precursor Al-rich clay mineral. Ooid sheaths were built by rolling of cores on ue sea floor. Glauconitic greensands and chamositic oolitic ironstones are condensed sequences deposited as sandwaves during long periods of reduced influx of sediment. Some are associated with hardgrounds.     

Comparative toxicities of chlorinated biphenyls on sea urchin egg fertilisation and embryogenesis

The aim of this study was to compare the biological actions of selected chlorinated biphenyls (CB's) (with different degrees of chlorine substitution), using the sea urchin test system, for their ability to affect fertilisation, embryogenesis and mitotic activity. Sea urchin embryos were exposed to the test agents throughout larval development or for shorter intervals (e.g. before or after hatching). Sperm or eggs were exposed before fertilisation, thereafter the contaminants were removed from embryo cultures. The results showed maximal activities from medium-chlorinated (tetra- and hexachloro-substituted) compounds, as compared to low- and high-chlorinated biphenyls (mono-, di- and octachloro-substituted), at nominal levels ranging from 10⁻⁶m to 10⁻⁵m. This held true for the different parameters and treatment schedules. Developmental defects were only detected following post hatching exposure of embryos to CB's, whereas pre-hatching exposure failed to reveal any embryological or cytogenetic abnormalities.     

A permanent seismic station beneath the Ocean Bottom

The Hawaii Institute of Geophysics began development of the Ocean Subbottom Seisometer (OSS) system in 1978, and OSS systems were installed in four locations between 1979 and 1982. The OSS system is a permanent, deep ocean borehole seismic recording system composed of a borehole sensor package (tool), an electromechanical cable, recorder package, and recovery system. Installed near the bottom of a borehole (drilled by the D/V Glomar Challenger), the tool contains three orthogonal, 4.5-Hz geophones, two orthogonal tilt meters; and a temperature sensor. Signals from these sensors are multiplexed, digitized (with a floating point technique), and telemetered through approximately 10 km of electromechanical cable to a recorder package located near the ocean bottom. Electrical power for the tool is supplied from the recorder package. The digital seismic signals are demultiplexed, converted back to analog form, processed through an automatic gain control (AGC) circuit, and recorded along with a time code on magnetic tape cassettes in the recorder package. Data may be recorded continuously for up to two months in the self-contained recorder package. Data may also be recorded in real time (digital formal) during the installation and subsequent recorder package servicing. The recorder package is connected to a submerged recovery buoy by a length of bouyant polypropylene rope. The anchor on the recovery buoy is released by activating either of the acoustical command releases. The polypropylene rope may also be seized with a grappling hook to effect recovery. The recorder package may be repeatedly serviced as long as the tool remains functionalA wide range of data has been recovered from the OSS system. Recovered analog records include signals from natural seismic sources such as earthquakes (teleseismic and local), man-made seismic sources such as refraction seismic shooting (explosives and air cannons), and nuclear tests. Lengthy continuous recording has permitted analysis of wideband noise levels, and the slowly varying parameters, temperature and tilt.Hawaii Institute of Geophysics Contribution 1909.     

Wave forces on submarine pipelines near a plane boundary

Forces induced by regular waves on submarine pipelines resting on as well as near a plane boundary and aligned parallel to wave fronts of the oncoming waves are investigated experimentally. The inline hydrodynamic coefficients of drag and inertia are evaluated through the use of Morison equation and the least squares method. The transverse force is analysed in terms of maximum transverse force and transverse root mean square (r.m.s.) coefficients. The resulting inline and transverse hydrodynamic coefficients are correlated with the period parameter or Keulegan-Carpenter number and relative clearance of the pipeline from the plane boundary. The effect of depth parameter on these coefficients and the correlation between maximum transverse force and transverse r.m.s. coefficients are also reported.     

The influence of dissolved petroleum hydrocarbon residues on natural phytoplankton biomass

The effect of dissolved petroleum hydrocarbons in the environment on phytoplankton biomass measured as chlorophyll a was studied near the oil tanker route in the southern Bay of Bengal. In the transect from 5° N, 77° E to 5° N, 87° E the concentrations of dissolved petroleum hydrocarbons were negatively correlated with phytoplankton biomass, whereas in the 0° N, 87° E to 1° N, 79° E transect they were positively correlated with phytoplankton biomass. The mean petroleum hydrocarbon concentrations in the two transects were 12·12 ± 4·67 μg litre⁻¹ and 11·23 ± 4·5 μg litre⁻¹, respectively.It is surmised that the effect of dissolved petroleum hydrocarbons on phytoplankton biomass varies depending on the nature rather than the quantity of petroleum hydrocarbons present. Culture studies with unialgal Nitzschia sp. in seawater collected from selected stations in the study area as well as in artificial seawater spiked with the water-soluble petroleum hydrocarbon fraction of light Arabian Crude support this.