Benthic foraminifera distribution in the modern sediments of the Southeastern Baltic Sea with respect to North Sea water inflows

Ponomarenko, E. P.; Krechik, V. А.

doi:10.2205/2018es000632

Cited by 5 publications

(2 citation statements)

References 11 publications

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“…In general, the benthic foraminiferal assemblages analysed are dominated by calcareous tests of the genus Elphidium and a few arenaceous Reophax dentaliniformis, which agrees with earlier down-core studies by Brodniewicz (1965), Hermelin (1987) and Krechik (2018). In addition, Lutze (1965) reported Elphidium excavatum f. clavatum (defined as Cribrononion excavatum f. clavatum) in surface sediments as the dominant taxon inhabiting the Gotland Basin during the AD 1962-1964 saline water inflows.…”

Section: Benthic Foraminiferasupporting

confidence: 87%

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Giant saltwater inflow in AD 1951 triggered Baltic Sea hypoxia

Moros,

Kotilainen,

Snowball

et al. 2023

Boreas

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A marked sedimentological change in subsurface sediments from the entire Baltic Proper, the Baltic Sea, has been previously noted. Our detailed work on a variety of multi‐cores from basin‐wide transects indicates that this sedimentological change was caused by a large shift in environmental conditions during the 1950s. Until the 1950s, the water column was rather weakly stratified and winter‐time convection – although weakened during the post Little Ice Age warming – was still able to ventilate the bottom waters of the Baltic Proper. Therefore, complete sediment sequences only accumulated in calm waters deeper than 150–160 m. High‐resolution benthic foraminiferal records of subsurface sediments obtained along the saline water inflow pathway in combination with historical data indicate that the depositional environment changed drastically owing to the giant saline water inflow in AD 1951. The accompanied sharpening of the halo(pycno)cline triggered a collapse in the ventilation of the basin, resulting in oxygen‐deficient bottom waters. This deficiency, in turn, caused the onset of phosphate release from the sediments, which accelerated primary production. The ventilation collapse also enabled the onset of deposition of organic carbon‐rich sediments also in shallower water areas as calm conditions prevailed up to the modern winter mixing depth (60–70 m). A slight return to Little Ice Age‐type conditions was observed during the late 1980s when temperatures decreased and stratification weakened. These conditions gave rise to a reduction in hypoxic areas and to a bottom‐water ventilation, most pronounced in the north of the so‐called Baltic Sea Klint, a hydrographic and topographic barrier. However, the general environmental conditions essentially have not changed since the 1950s. Remarkably, external (temperature and stratification) in combination with internal factors (e.g. ventilation collapse and phosphate release) were able to change the redox conditions of the Baltic Proper from oxic to hypoxic within less than 10 years.

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Section: Benthic Foraminiferasupporting

confidence: 87%

“…(2018), Van Wirdum et al . (2019) and Ponomarenko and Krechik (2018). In addition, Lutze (1965) reported Elphidium excavatum f. clavatum (defined as Cribrononion excavatum f. clavatum ) in surface sediments as the dominant taxon inhabiting the Gotland Basin during the AD 1962–1964 saline water inflows.…”

Section: Resultsmentioning

confidence: 97%