The atlas presents an analysis of relative abundances of extant planktic foraminifera (>150 µm) in surface sediments of the Indian Ocean and the North Atlantic, based on CLIMAP data. Relative abundances of each species are plotted against latitude, and winter, summer, mean values, and a seasonality parameter of temperature, salinity, and water density at the sea surface and at 200 m depth, the vertical temperature gradient and the density contrast (stratification) between the sea surface and 200 m depth, based on data from Levitus (1982).

The analysed species are: C. nitida, D. anfracta, G. bulloides, G. falconensis, G. digitata, G. calida, G. siphonifera (syn. G. aequilateralis), G. glutinata, G. conglobatus, G. ruber, G. sacculifer, G. conglomerata, G. crassaformis, G. hirsuta, G. inflata, G. menardii, G. scitula, G. truncatulinoides, G. tumida, G. hexagonus, G. rubescens, G. tenella, H. pelagica, N. dutertrei, N. pachyderma, O. universa, P. obliquiloculata, S. dehiscens, T. humilis, T. quinqueloba; and with sporadic occurrences in a few samples: B. pumilio, G. adamsi, G. uvula (syn. G. bradyi), T. iota, and H. digitata. Some species were not recorded due to their small size (<150µm): G. vivans, G. minuta, O. riedeli, S. globigerus, T. clarkei, T. fleisheri, T. parkerae; or for other reasons: G. cavernula, G. theyeri, and G. ungulata. The biogeographic ranges, suboptima, and optima with respect to the analysed parameters are presented in tabular form for each species with continuous occurrences.

The six dominant species have broad relations with sea surface temperature, with optima in the various biogeographic provinces, or preferences for productive marine environments. Other species show specific relations with combinations of physical parameters which reflect specialisation and individual niches. A third group is part of bloom successions or seasonal productivity variation and is differentiated by their preferences for conditions in high latitudes and upwelling zones, tropical environments, or processes related to the deep chlorophyll maximum. Species with known ontogenetic cycles show closest relations with physical conditions in their time of reproduction, suggesting a dominance of reproduction-related processes for control of relative abundances in sediment assemblages.

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