Wind Stress and Primary Production

Wind stress plays an important role in controlling PPs in the oceans because it can break stratification of the open ocean bringing nutrients to the upper part of the photic zone, inducing an increase in PP. This relation between wind and PP in the Indian Ocean has been demonstrated by a sedimenttraps study (Nair et al., 1989) that shows that the flux of organogenic material increases in September and October, a couple of months after the height of the monsoon. This indicates that peaks in PP closely follow strong wind activity. Pronounced seasonal response of PP from wind strength can be identified by comparing PP estimates from satellite imagery with seasonal wind stress data from COADS data sets; e.g., in the western Indian

Zone of production of most of the coccolithophores level of light limitation for most of the coccolithophores

Zone of production of Florispheara profunda

Base of the photic zone

0 20 40 60 80 100

%F. profunda

Figure 1: (A) Schematic representation of the influence of the depth of nutricline on the percentage of Florispheara profunda in coccolithophore assemblages. Black curve represents the amount of nutriments through depth in the photic zone; the grey curve, the amount of light; and the filled area the primary production. The dotted lines are levels of light limitation for most of the coccolithophores (shallow) and F. profunda deep. Two cases are shown: left is with a shallow nutricline, right with a deep nutricline. (B) Relationship between the percentage of F. profunda in 94 core top samples from the Indian Ocean (Beaufort et al., 1997) and primary production estimated from satellite imagery (Antoine et al., 1995). The line corresponds to the equation PP — 617-(279 log[%Fp+3]) which represent the best fit with a correlation (r — 0.94).

light intensity Nutriment concentration Primary production light intensity Nutriment concentration Primary production

Zone of production of most of the coccolithophores level of light limitation for most of the coccolithophores

Zone of production of Florispheara profunda

Base of the photic zone

Case of shallow Nutricline high primary production low % of F. profunda

Case of deep nutricline low primary production high % of F. profunda

Case of shallow Nutricline high primary production low % of F. profunda

Case of deep nutricline low primary production high % of F. profunda

0 20 40 60 80 100

%F. profunda

Figure 1: (A) Schematic representation of the influence of the depth of nutricline on the percentage of Florispheara profunda in coccolithophore assemblages. Black curve represents the amount of nutriments through depth in the photic zone; the grey curve, the amount of light; and the filled area the primary production. The dotted lines are levels of light limitation for most of the coccolithophores (shallow) and F. profunda deep. Two cases are shown: left is with a shallow nutricline, right with a deep nutricline. (B) Relationship between the percentage of F. profunda in 94 core top samples from the Indian Ocean (Beaufort et al., 1997) and primary production estimated from satellite imagery (Antoine et al., 1995). The line corresponds to the equation PP — 617-(279 log[%Fp+3]) which represent the best fit with a correlation (r — 0.94).

Ocean (Beaufort et al., 1999), Central Indian Ocean (Beaufort et al., 1997) and Sulu Sea (de Garidel-Thoron et al., 2001).

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