The identification of the nutrients likely to limit phytoplankton in the Tuamotu Archipelago ocean (South Pacific subtropical gyre) is deduced from DIN (NO3-+ NOz-+ NH,'), PO,", and SiOz in situ concentrations and strengthened by the results of 4 other studies on the same area:(1) 0,,,, the maximum quantum yield of photosynthesis, (2) phytoplankton cell size, (3) nutrient enrichment on natural populations, (4) bacterial biomass and nutrient limitation of bacteria. The low D,,,, and the small s~z e of phytoplankton support the idea of nutrient control. Low DIN concentrations (mean = 0.02 PM), low average D1N.P-PO,*^ ratios = 0.3 at:at, low average DIN:Si02 = 0.04 at:at, and significant increases of phytoplankton standing stock and bacterial production after N enrichments point to N a s the main limiting nutrient. P is the second limiting nutrient as evidenced by the relative low phosphate concentrations (0.2 PM) and by the synergetic effect of DIN + PO," enrichments. Silicon concentrations appear to limit the proliferation of siliceous taxa as evidenced from its average concentration of 1 pM and from the scarcity of diatoms. Natural collcentrations of vitamins, MO, Mn, Fe and chelators are sufficient to support the increase of phytoplankton standing stock induced by N and P additions and therefore are not limiting.

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The MEFO is a valid and reliable test for discriminating between dementia and CI sufferers and subjects with no CI. Its validity is similar to that the MMSE under these conditions, but it is more effective for identifying subjects with MCI and its administration time is shorter.