Ecology and stable isotope geochemistry of modern planktonic foraminifera in the Northeast Atlantic
The understanding of the relationship between planktonic foraminifera and their surrounding environment, as well as each individual speciesa habitat and calcification behaviour are of fundamental importance to improve their use as a paleoceanographic tool. To this end, vertically stratified plankton...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Universität Bremen
2018
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| Online Access: | https://media.suub.uni-bremen.de/handle/elib/1550 https://nbn-resolving.org/urn:nbn:de:gbv:46-00107001-17 |
| Summary: | The understanding of the relationship between planktonic foraminifera and their surrounding environment, as well as each individual speciesa habitat and calcification behaviour are of fundamental importance to improve their use as a paleoceanographic tool. To this end, vertically stratified plankton tow hauls were used to study the vertical and horizontal distribution and stable isotope geochemistry of planktonic foraminifera in the eastern North Atlantic, a region that plays an important role in monitoring changes in the North Atlantic circulation and where the environmental conditions are particularly diverse. This work provides new insights into the vertical and horizontal distribution of individual species of planktonic foraminifera and the respective factors (temperature, chlorophyll, mixed layer depth, lunar/seasonal cycle) potentially controlling their distribution. New findings concerning the stable isotope signal recorded in the shells of four deep dwelling planktonic foraminifera species are also reported. The vertical distribution of planktonic foraminifera varied among species, allowing us to identify different groups of species, such as species living typically above 100 m, species occurring commonly between the surface (50 m) and intermediate waters (100 m) and species living mostly below 100 m. In most cases, the vertical habitat also varied within species, but the variation was found to be predictable by a combination of environmental factors and ontogenetic migration. Horizontally, species distribution is linked to the surrounding environmental conditions, resulting in specific regional and seasonal faunal associations. Unlike the composition of sedimentary assemblages, plankton assemblages are predicted by multiple environmental parameters, indicating that the strong temperature signal in fossil assemblages is the result of seasonal and interannual accumulation and averaging. The stable isotopic analysis of four deep-dwelling species confirmed that either larger size or presence of a secondary ... |
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