The percentual distribution and frequency of occurrence of diatoms in bottom sediments in the Airisto and Paimionlahti regions in southwest Finland
This study deals with the occurrence and percentual distribution of diatoms in the Airisto and Paimionlahti regions in southwest Finland. The formation of sediments in the area has been influenced by land uplift and the resultant phases in the evolution of the Baltic Sea. These have affected the fre...
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| Format: | Article |
| Language: | English |
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Geological Society of Finland
1987-12-01
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| Series: | Bulletin of the Geological Society of Finland |
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| Online Access: | http://www.geologinenseura.fi/bulletin/Volume59/sgs_bt_059_2pages_155_170.pdf |
| Summary: | This study deals with the occurrence and percentual distribution of diatoms in the Airisto and Paimionlahti regions in southwest Finland. The formation of sediments in the area has been influenced by land uplift and the resultant phases in the evolution of the Baltic Sea. These have affected the freshwater and brackishwater content of the Baltic. Simultaneous with deposition of the sediments, there has been a change from open water to the present kaleidoscopic character of the archipelago. The diatom flora of the sediments proved to be very varied. Freshwater sediments are characterised by large individual numbers of a few species, Melosira islandica and Stephanodiscus astraea, while brackish-water sediments have a more even distribution of many species. The effect of redeposition can be seen clearly in the diatom flora of the sediments. There was a clear correlation between the numbers of certain diatoms but, on the whole, the correlations were small if the large numbers of species are borne in mind. The saltier Mastogloia phase could be clearly distinguished in many cores. The diagrams show that the species have considerably multiplied in variety in more recent sediments. Coscinodiscus granii, Coscinodiscus asteromphalus and Achnanthes taeniata, which predominate in young sediments, have achieved their present abundance only in the most recent sediments. This has taken place at the expence of Epithemia species, for example. |
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| ISSN: | 0367-5211 1799-4632 |