This atlas shall be a tool to communicate microfossil ecology and applications of planktic foraminifera to the students, to support differentiated interpretations of microfossil assemblages in professional research, and to show underlying causes of biogeographic pattern in the relationships of species with the physical environment and its seasonal variation. The atlas makes use of the extensive data collected by the CLIMAP project and Levitus (1982). It has been compiled as a graphical visualisation of the relationships of relative abundances of modern planktic foraminifera and the physical environment. This approach seemed necessary because most large data sets in this field have been reduced through multivariate statistical methods. The mathematical treatment allows for fast and easy access of results but it also hides structure in the data and presents mathematical problems where the relationships of relative abundances and physical parameters follow complicated distribution pattern. It is this complicated pattern, however, that is characteristic for some species. The graphic approach is demanding. The reader has to extract information from numerous plots of relative abundance vs. physical parameters. Through this effort the reader will experience the multivariate character of ecological relationships in planktic foraminifera. Their distribution follows a combination of parameters that are characteristic for the individual niches of species. The graphic approach allows to access and to discuss these relationships in a less abstract form than in output from a multivariate statistical procedure.

Planktic foramnifera belong to the most intensely studied groups of geologically relevant organisms and, therefore, much is known about their ecology at least on a qualitative scale. This concerns mostly biogeographic pattern which has been summarised and reviewed in numerous papers. This atlas will necessarily reproduce some of this information but may help to extract more information from the published maps of biogeographic distributions and statistical data. The brief descriptions of the plots for every species shall help to see relevant pattern in the plots. They are not intended as a comprehensive review of the ecology of these species and of the literature published on this subject.

Previous studies were mostly focussed on relations of planktic foraminifera with the properties of surface waters. I included the conditions at 200 m depth in the analysis. At this depth the seasonal variation is neglectable and results can give an insight in effects of contrasts between the mixed layer and the central waters. The plots show close relationships of relative abundances of numerous deeper dwelling species with the seasonally variable stratification in the upper ocean. This observation may be used in paleoceanographic work and other new applications of planktic foraminifera. It may also help to interpret isotope data from some species that have to be seen in the light of preferences for certain oceanographic conditions and their seasonal variation.

Zürich, August 1996

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