Shelf seas

Fig. 2.5 Timeseries of daily phytoplankton, zooplankton, dissolved organic carbon, detritus, and phosphorus concentration, and photosyntesis over one model year at two location the shelf seas of the Pacific Ocean, 170 E 65 N and 140 E 10 S.

Zhao, Y.Y. Yan, M.C. 1994. Geochemistry of Sediments of the China Shelf Sea. Beijing Science Press, 203p. (in Chinese). 

Data now indicate that prior to a bloom of toxic dinoflagel-lates and subsequent shellfish intoxification there are a few prerequisites. Namely 1) bay, estuary and/or shelf sea where there is 2) seasonal stratification, 3) frontal boundary layers (22), and/or 4) tremendous energy resulting from major tidal dissipation (23). 

THE NORTH-WEST EUROPEAN SHELF SEAS THE SEA BED AND THE SEA IN MOTION... 

Compared with the open water of the Arctic Ocean, the shelf seas of the Russian Arctic are more heavily contaminated. 

Dyke, P.P.G (2001) Coastal and Shelf Sea Modeling. Kluwer International Series Topics in Environmental Fluid Mechanics. Kluwer Academic, London. 

Massie, K. S. in The North-West European Shelf Seas The Sea Bed and the Sea in Motion. II Physical arui Chemical Oceanography and Physical Resources, (F. T. Bauner, M. B. Collins and K. S. Massie, eds.), Elsevier, New York, 1980, Chap. 19, p. 569. 

Michelson, A. A., Gale, H. G., 1919. The rigidity of the Earth, Astrophysical Journal, 50, 330-345. Miiller-Navarra, S. H., 2002. Implementation of the equilibrium tide in a shelf sea model. Environ-... 

Backhaus, J. O., 1985. A three-dimensional model for simulation of shelf sea dynamics. Deutsche Hydrographische Zeitschrift, 38, 165-187. 

Mauchline, J. (1980) Artificial radioisotopes in the marginal seas of north western Europe. In The North-west European Shelf Sea the Sea Bed and the Sea in Motion. II. Physical and Chemical Oceanography and Physical Resources, eds. F.T. Banner, M.B. Collins and K.S. Massie, 517-42. Elsevier. Amsterdam. 

It can be seen that the shape of the ocean basins and the distribution of continental masses have an important effect on currents and the location of high productivity zones. The degree of flooding of continental margins, which is controlled by the relative volumes of ocean basins and seawater, is also important in terms of the area of productive coastal waters. Nutrient supply from land, via rivers, can contribute to the productivity of shelf seas. 

These statistics underscore the importance of the continental shelf areas to the structure and function of the Arctic Ocean system. Arctic shelf seas are the primary sites for processing and modifying the characteristics of waters received from the Pacific and Atlantic Oceans and the numerous large rivers that drain the circumpolar continents. All of these inflows are substantially altered on the shelves by mixing and by interactions with the ice cover, atmosphere, seabed and biota. The water mass properties that generate and maintain the halocline in the Arctic Ocean (see Section 5.2.1) are derived from the modification of inflowing Atlantic and Pacific waters while transiting continental shelves. 

Anderson, L.G. (1995) Chemical oceanography of the Arctic and its shelf seas, in Arctic Oceanography Marginal Ice Zones and Continental Shelves (eds W.O. Smith Jr. and J.M. Grebmeier), American Geophysical Union, Washington, DC, pp. 183-202. 

Influence of nutrient biogeochemistry on the ecology of northwest European shelf seas... 

We focus on temperate shelf seas because these are not only best studied, but also most subject to anthropogenic influence. Most of our examples are taken from studies in northwest European waters, because it is these that we know best. The aim of this chapter is to review recent improvements in knowledge of the sources and sinks of nutrients in the shelf seas of northwest Europe, and to consider, especially, the influence of ratios of nutrient elements on the floristic composition of the phytoplankton in these seas. We deal mainly with the macronutrient elements nitrogen, phosphorus and silicon, and to some extent with iron. The acronym DAIN (Dissolved Available /norganic Mtrogen) is a convenient way to refer to nitrate, nitrite and ammonium, excluding di-nitrogen which is not available to most phytoplankters. 

The issue of atmospheric deposition as a transport mechanism for nutrients to coastal shelf seas is a relatively recent one. However, it has now emerged as being of great importance for the following reasons. Firstly, this method is very significant in a quantitative sense (Rendell etal., 1993 Asman etal., 1995). Secondly, the deposition of material frequently occurs some way out to sea (Jickells, 1995), where the impact of biological processes in the immediate coastal zone has already reduced nutrient concentrations to undetectable levels. Particular sources of nutrients include agricultural emissions from livestock and motor vehicle exhaust fumes. 

The starting point for production on the shelf is the build up of concentration over winter. The concentration at a particular point is determined by recycling from organic matter in water column and seabed, input from the atmosphere, and exchange with surrounding waters, themselves influenced by oceanic and riverine source waters. In the case of a well-mixed shelf sea in winter, the... 

This rapid increase with width gives broader shelf seas an interior, across which transports should be considered in distinction to the effectively separate oceanic and coastal boundaries (Huthnance, 1995). 

A consequence of the relatively long transport times in northwest European shelf seas is that, in the interior, concentrations cannot be predicted from end member concentrations. As we have seen above, this is particularly true for concentrations of nitrate due to denitrification. In winter, concentrations of nutrients can be lower in shelf seas than in adjacent ocean surface water masses (Hydes etal., 2001 Gowen etal., 2002). Maps of winter distributions of the ratio of N P show regions of minimum values in those waters furthest from river and ocean source waters (Hydes Edmunds, 1992 Brockmann Wegner, 1995 Brockmann Kattner, 1997). 

Gowen, R.J., Hydes, D.J., Mills, D.K., Stewart, B.M., Brown, J., Gibson, C.E., Shammon, T.M., Allen, M. and Malcolm, S.J. (2002) Assessing trends in nutrient concentrations in coastal shelf seas a case study in the Irish Sea. Estuarine, Coastal and Shelf Science, 54, 927-939. 

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