There are many measures of primary production. Since the question of respiration in radiocarbon measurement was resolved by Steemann Nielsen and Hansen (1959) and the problem of calibration was dealt with by Steemann Nielsen (1964) and by Goldman (1968), most of the doubts raised about the method in the fifties have disappeared. Further, Koblents-Mishke (1965) has combined the surface observations (in mgC/m³/d) with those at a number of depths in the photic layer (mgC/m²/d); her regression has been used in this paper to convert surface observations in mgC/m³/d to gC/m²/d. Given an adequate average estimate of mgC/m²/d, the seasonal or annual production can be readily calculated.
The data used are those of Steemann Nielsen and Jensen (1957), from the Galathea Expedition in the Atlantic and Indian Oceans, Ryther et al., (1966) from the Anton Bruun to the Indian Ocean Expedition, and Kabanova (1964) from the Vityaz in the Indian Ocean. The summaries of the Pacific Ocean data of Koblents-Mishke (1965), Blackburn (1966) and Angot (1961) have been used extensively. Forsbergh and Joseph (1964), and Holmes, Schaefer and Shimada (1957) give observations made off Peru, northern Chile, in the Costa Rica Dome and in the equatorial region. Doty (quoted in Angot, 1961) has made many measurements in the Indonesian region, which (however) are higher than those of Steemann Nielsen and Jensen and Angot made in the same region, so his measurements have not been used.
Figure 15 gives Koblents-Mishke's figure of production in the Pacific as mgC/m²/d. This figure shows the high latitude divergences, north and south, the Californian upwelling, the Peruvian upwelling and that off northern Chile. The extensive region of divergence in the eastern tropical Pacific extends into the zone of production along the equator. This is the region of divergence in the South Equatorial Current, and east of 140°W, i.e. above the Cromwell Undercurrent. The productive areas near New Guinea and the Philippines are shown, as well as productive areas off Australia and New Zealand and off Japan.
Figure 15. Distribution of production, in mgC/m²/d, in the Pacific (Koblents-Mishke, 1965)
In the Atlantic, there are some observations on the African coast, mainly from the Galathea Expedition. There are a few observations in the two southern areas of the Canary upwelling during November. In the Benguela Current there is adequate coverage in all four regions during the period December to January, sampling the main period of upwelling. In the Indian Ocean there are observations from Vityaz and the Anton Bruun covering the Somali Current, the southwest Arabia upwelling and the Madagascar wedge during the period of upwelling. They are supported by other observations summarized in Wooster, Schaefer and Robinson (1967). Off Orissa, there are only three observations from the Vityaz and off the Andaman coast there are only two, which are not enough to estimate a proper average. In the Indonesian area, including the South China Sea, there are observations taken on the Galathea Expedition and a number summarized by Angot (1961). The Japan Science Council, National Committee for IIOE (1966) has also summarized some observations off Java and northwest Australia. There are a few observations in each of the Flores, Banda and Arafura Seas. There are a number of observations off Vietnam and in the Gulf of Thailand.
In Table I the radiocarbon observations are classed and averaged by the upwelling areas. The observations by the areas and season set out in section 4 were expressed as a single average for the upwelling area. Treating the sampling as adequate in each region (which it is not, off Orissa or off the Andaman Islands), the area in km² is given with the duration of the season in days (from section 6); the production of carbon in each upwelling area is then given as tons C.106/yr. The figures have then been rounded off to the levels of 3, 5, 10, 20 and 50 tons C.106/yr.
Steemann Nielsen (1964) has found that the original method of standardization underestimated the true production by 45 per cent and his estimate has recently been confirmed by Goldman (1968). Nearly all the observations reported here contain the same error, based on a linear extrapolation of the self-absorption curve; it was not considered practicable to search for the few observations that might have been standardized with a different method. A general correction is therefore made in column E of Table I. The final result in each region is really an average figure of carbon production, raised by area and season. There are not enough observations to establish seasonal cycles in the upwelling areas.
From Table I it will be seen that the differences in mgC/m²/d are less than those in tons 106/yr. This is really only to be expected, because the differences are due to area and length of season. The Indian Ocean upwellings are less important than the four major upwellings because the season is limited to one monsoon - but the steady persistence of the monsoon winds makes the southwest Arabian area, at least, more important than, for example, the Californian area.
Confidence limits have not been calculated for each area, for two reasons: (1) there are not enough observations to establish seasonal trends which are important in some areas, (2) in some areas, e.g. the Canary Current, the Bay of Bengal and in some parts of the Indonesian area, observations are few. However, with the exception of those observations off Orissa and the Andaman coast, there are enough observations to establish fairly reliable means.
Although the 278 tons C.106/yr in the Benguela Current may not differ from the 155 tons C.106/yr in the Peru Current, the two quantities do differ from the 30 tons C.106/yr estimated for the California Current, and 35 tons C.106/yr off southwest Arabia. Column F in Table I gives rounded figures of 5, 10, 35, 75 tons C.106/yr (amongst others) which probably express real differences. So the Peru and Benguela Currents are the main upwelling areas (75.106 t C/yr +), with California, southweet Arabia, Chile, New Guinea, Java and Vietnam as intermediate areas (ca 30.106 t C/yr), and the Somali Current, Costa Rica Dome, Madagascar Wedge, Orissa coast and the Indonesian areas as minor ones (5-10.106 t C/yr).
