Numerical modelling of the Sea of Azov's dynamics resulting from narrowing of the mouth of Taganrog Bay

The currents and surface level oscillations in the Sea of Azov ensuing from contraction of the mouth of Taganrog Bay are computed using the grid technique on the basis of a numerical solution to the system of quasi-linear, degenerate, parabolic, partial derivative equations (shallow-water equations). It is demonstrated what changes are to be expected in the dynamics of the Sea of Azov should this project be realized. The computations were carried out for typical wind directions.Translated by Vladimir A. Puchkin.     

The rise of coastal and marine tourism

Marine tourism has surfaced as a pressing topic in the field of ocean and coastal management. Neither necessarily good, nor bad, this tourism is inherently controversial. Today, demand for travel exhibits greater variation and magnitude than ever in history. In response, the tourism industry has become the largest business on earth. This, coupled with the respect people profess for marine environments and local peoples, creates feelings of ambivalence for the tourist. Sociologically, the activity of tourism may be studied as a symbolic interaction fostering social solidarity. Ecotourism, a recent phenomenon attuned to the ideal of sustainable development, is suggested to emerge through the social construction processes of restoration and enhancement. The papers in this theme volume add fuel to the proposition that the resolution of tourism problems in the coastal zone will require the scientific study of environmental and social conditions, policy analyses, planning, and public education.     

Phosphate adsorption and desorption in a tropical estuary (Maracaibo system)

The Maracaibo Estuary is of particular interest because of its location in the tropics, its large size (over 12,000 km²), the economic importance of its underlying hydrocarbon deposits and its increasing rate of pollution. Sediments from this estuary were studied in order to characterise their capacity to adsorb and desorb phosphorus. Considerable variability in capacity for phosphate sorption was found among the seventeen samples studied. This variability can be attributed first to the differences among the samples in total P content and, secondly, to their differences in free iron content. Also, it appears that P retention contributes to the control of P concentration in the water and therefore the sediments serve as a buffer in controlling P eutrophication in the estuary.     

Regimes and the history of the major fisheries off Canada's west coast

The major fisheries on the Pacific coast of Canada can be grouped into 12 species that have consistently represented about 80–90% of the total catch from the past to the present. A review of population dynamics of these species indicates that climate and the ocean environment have a major impact on their productivity. We review the history of Canada's Pacific coast fishery to show that trends in catch were similar to trends in the climate and ocean environment. Decadal scale patterns in climate and the ocean are termed regimes and we show that it is the regime scale of climate variability that most influences the long-term trends in the catches in these major fisheries. Ignoring the impacts of regime shifts on the abundance trends in the future could result in collapses of major fisheries. The difficulty of knowing when a regime shift will occur may be overcome as we discover more about the mechanisms that affect the decadal-scale trends in the rotational velocity of the solid earth which is measured as the length of day (LOD).     

Jason-1: Assessment of the System Performances

On 7 December 2001, Jason-1 was successfully launched by a Boeing Delta II rocket from the Vandenberg Air Force Base, California. The Jason-1 satellite will maintain the high accuracy altimeter service provided since 1992 by TOPEX/Poseidon (T/P), ensuring the continuity in observing and monitoring the Ocean Dynamics (intraseasonal to interannual changes, mean sea level, tides, etc.). Despite one-fourth the mass and power, the Jason-1 system has been designed to have basically the same performance as T/P, measuring sea surface topography at a centimetric level. This new CNES/NASA mission also provides near real-time data for sea state and ocean forecast. The first two months of the Jason-1 mission have been dedicated to the assessment of the overall system. The goals of this assessment phase were:

1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);

2. To verify that platform performance requirements are met with respect to Jason-1 requirements;

3. To verify that payload instruments performance requirements evaluated at instrument level are met;

4. To assess the performance of the Jason-1 Ground System.

This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products.     

Seasonal variation of pteropods from the Western Arabian Sea sediment trap

Sediment trap samples collected from the Western Arabian Sea yielded a rich assemblage of intact and non-living (opaque white) pteropod tests from a water depth of 919 m during January to September 1993. Nine species of pteropods were recorded, all (except one) displaying distinct seasonality in abundance, suggesting their response to changing hydrographical conditions influenced by the summer/winter monsoon cycle. Pteropod fluxes increased during the April–May peak of the intermonsoon, and reached maximum levels in the late phase of the southwest summer monsoon, probably due to the shallowing of the mixed layer depth. This shallowing, coupled with enhanced nutrient availability, provides ideal conditions for pteropod growth, also reflected in corresponding fluctuations in the flux of the foraminifer Globigerina bulloides. Pteropod/planktic foraminifer ratios displayed marked seasonal variations, the values increasing during the warmer months of April and May when planktic foraminiferal fluxes declined. The variation in fluxes of calcium carbonate, organic carbon and biogenic opal show positive correlations with fluxes of pteropods and planktic foraminifers. Calcium carbonate was the main contributor to the total particulate flux, especially during the SW monsoon. In the study area, pteropod flux variations are similar to the other flux patterns, indicating that they, too could be used as a potential tool for palaeoclimatic reconstruction of the recent past.     

In situ velocity profiles in gassy sediments: Kiel Bay

Acoustic behavior of gas-bearing sediments is significantly different from that of gas-free sediments. In situ velocity profiles and acoustic signal characteristics in gas-bearing sediments of the upper several meters of the sea floor in Kiel Bay are presented in this study. Observed velocities in gas-bearing sediments are both higher and lower than those of the gas-free sediments. Small amounts of gas appear to cause signal reverberation without much attenuation. whereas large amounts of gas cause substantial attenuation.