Holocene Environmental History of the Little Belt Region, Baltic Sea
Abstract
The Baltic Sea has experienced a complex geological history, with notable swings in salinity driven by changes to its connection with the Atlantic and glacioisostatic rebound. Sediments obtained during International Ocean Drilling Program Expedition 347 allow studying the effects of these changes on the ecology of the Baltic in high resolution through the Holocene in areas where continuous records had not always been available. Site M0059 was drilled in the Little Belt region, one of the connections between the Baltic Sea and the Atlantic Ocean. Diatom species level analysis at a 20 cm resolution reveals 6 distinct ecological zones spanning the past 8,000 years.
Specifically, an oligotrophic nearly freshwater zone of the Initial Littorina Sea assemblage is seen in the lowest sample depths. Nutrient content of the water column increases before salinity, leading into the remainder of the Initial Littorina Sea stage, which is classified as eutrophic. Subsequently, the Littorina Sea becomes oligotrophic and is dominated by tychopelagic diatoms. The later Littorina Sea sediments contain a diatom assemblage more similar to that of the Northern Atlantic Ocean, composed primarily of cosmopolitan marine diatoms. This is followed by the modern Baltic Sea stage and a return to tychopelagic primary productivity. Anthropogenic eutrophication is detected in the last 300 years of the record which intensifies in the uppermost sediments reflecting industrialization. Changes to water depth, benthic primary productivity and water column stratification are also considered.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP33C1741W
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 1050 Marine geochemistry;
- GEOCHEMISTRYDE: 1833 Hydroclimatology;
- HYDROLOGYDE: 4914 Continental climate records;
- PALEOCEANOGRAPHY