. The Composition of sea-water : comparative and descriptive oceanography. Seawater -- Composition. SECT. 2 J PRODUCTIVITY, DEFINITION AND MEASUREMENT 157 is not found during the unproductive parts of the year. Although during the height of summer the rate of primary production is relatively low in certain areas of the north-eastern part of the North Atlantic (about 100 mg C/m2 per day), the depth of the photic layer does not exceed 60 m. The transparency in the ocean far from the coast reflects not only the actual primary production at the time but also to some extent the production which has
. The Composition of sea-water : comparative and descriptive oceanography. Seawater -- Composition. SECT. 2 J PRODUCTIVITY, DEFINITION AND MEASUREMENT 157 is not found during the unproductive parts of the year. Although during the height of summer the rate of primary production is relatively low in certain areas of the north-eastern part of the North Atlantic (about 100 mg C/m2 per day), the depth of the photic layer does not exceed 60 m. The transparency in the ocean far from the coast reflects not only the actual primary production at the time but also to some extent the production which has previously taken place in the water-mass. LEGEND __|0% deep blue "" 0-2%blue . '////^ 2-5%blue-^reen > 5 %qreen. Fijz. 18. Distribution of the colour of the sea. South Atlantic. (After Schott.) Fig. 18 (Schott in Hentschel, 1933-1936), showing the distribution of the colour of the sea in the South Atlantic, represents at the same time the rate of primary production. At present it is not possible to publish a much better relative chart for this area (see Steemann Nielsen and Aabye Jensen, 1957). It agrees even in detail with the measurements of primary production—and standing stock of phytoplankton—made in the South Atlantic. 6. The Significance of Single Individual Measurements of Primary Production The significance of single individual measurements of primary production must necessarily vary depending on the area from which the measurements originate. Both variations due to the sequence of seasons and to horizontal displacements of the water-masses must be considered. If a typical seasonal variation is found, as is always the case in the temperate and arctic zones, it is compulsory to make measurements throughout the productive season. If a field "station" is situated in the centre of a large and hydrographically. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration a
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