Pulleniatina obliquiloculata (Parker and Jones, 1865)

This species (Fig. 36) shows a remarkeable asymetric distribution against latitude. In the North Atlantic, between 30-40° latitude, west of about 50° longitude, a marked abundance peak occurs, while, if this peak is not considered, P. obliquiloculata has a very symmetric relation with latitude indicating a tropical to warm subtropical distribution. The North Atlantic abundance peak occurs where subtropical temperatures and low vertical temperature and stratification gradients exist, and may be related with the Gulf Stream. It is only the relation of relative abundance and temperature at 200 m where the resulting distribution is unimodal and a common ecological parameter can be identified. This may indicate a deep-water habitat of this species. The bimodal pattern suggests some relation with productive water masses, as in G. bulloides, but no clear relation with the northwest African upwelling zone exists. The geographic distribution suggests some relation with the western North Atlantic fronal systems around the Azores and the Canary Islands. High relative abundances of P. obliquiloculata were considered as a dissolution indicator by Kipp (1976).

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Figure 36: Pulleniatina obliquiloculata (Parker and Jones, 1865). Plots of relative abundance vs. selected physical parameters and latitude. For preferences in numeric form see appendix.

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