Rapid environmental responses to climate-induced hydrographic changes in the Baltic Sea entrance
| Autor: | L. M. Charrieau, K. Ljung, F. Schenk, U. Daewel, E. Kritzberg, H. L. Filipsson |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Biogeosciences, Vol 16, Pp 3835-3852 (2019) |
| Druh dokumentu: | article |
| ISSN: | 1726-4170 1726-4189 |
| DOI: | 10.5194/bg-16-3835-2019 |
| Popis: | The Öresund (the Sound), which is a part of the Danish straits, is linking the marine North Sea and the brackish Baltic Sea. It is a transition zone where ecosystems are subjected to large gradients in terms of salinity, temperature, carbonate chemistry, and dissolved oxygen concentration. In addition to the highly variable environmental conditions, the area is responding to anthropogenic disturbances in, e.g., nutrient loading, temperature, and pH. We have reconstructed environmental changes in the Öresund during the last ca. 200 years, and especially dissolved oxygen concentration, salinity, organic matter content, and pollution levels, using benthic foraminifera and sediment geochemistry. Five zones with characteristic foraminiferal assemblages were identified, each reflecting the environmental conditions for the respective period. The largest changes occurred around 1950, when the foraminiferal assemblage shifted from a low diversity fauna dominated by the species Stainforthia fusiformis to higher diversity and abundance and dominance of the Elphidium species. Concurrently, the grain-size distribution shifted from clayey to sandier sediment. To explore the causes of the environmental changes, we used time series of reconstructed wind conditions coupled with large-scale climate variations as recorded by the North Atlantic Oscillation (NAO) index as well as the ECOSMO II model of currents in the Öresund area. The results indicate increased changes in the water circulation towards stronger currents in the area after the 1950s. The foraminiferal fauna responded quickly ( |
| Databáze: | Directory of Open Access Journals |
| Externí odkaz: |
|