Globigerinoides sacculifer (Brady)

Globigerinoides sacculifer (Fig. 16) is abundant in tropical water masses. Clear relationships of relative abundance with sea surface temperature and the temperature at 200 m depth exist. The species has narrower tolerances for summer conditions in these parameters, surface water density and the vertical temperature gradient. The species has a preference for water masses with low seasonality in sea surface temperatures and low seasonality in vertical temperature gradients. G. sacculifer shows a maximum in relative abundance in water masses with near average marine salinity but the species has a very broad tolerance and is not a good indicator of salinity. See discussion section in this paper.

Some forms of G. sacculifer develop a distinct sac-like chamber in their terminal stage. They were counted as a separate category. The data in Fig. 16 is combined for sac and non-sac forms. Figure 17 shows correlations of relative abundances of sac and non-sac forms, and relations with selected physical parameters which do not suggest significant differences in the ecology of both forms, in agreement with culture experiments (Hemleben et al., 1987).

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Figure 16: Globigerinoides sacculifer (Brady). Forms with sac chambers included. Plots of relative abundance vs. selected physical parameters and latitude. For preferences in numeric form see appendix.

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Figure 17: G. sacculifer with and without sac chamber: correlation of relative abundances, geographic distribution, and relation with water temperature at 200 m. For discussion see text.

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