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Title [sv]
Senpleistocen och Holocen klimatpåverkan på Östersjön
Title [en]
Late Pleistocene and Holocene climate forcing on the Baltic Sea
Abstract [en]
During autumn 2013 the first ever scientific drilling expedition in the Baltic Sea was carried out within the International Ocean Discovery Program IODP Expedition 347, Baltic Sea Paleoenvironment. The overarching objective of Expedition 347 was to gain a deeper understanding of the paleoenvironmental evolution of the Baltic Sea Basin through the last glacial cycle. After the expedition, the following Onshore Science Party in early spring 2014 carried out visual inspection and description of the cores retrieved, measurements of physical properties, and intense sampling of the cores. Initial biostratigraphic and lithologic analyses provided a preliminary chronology that, together with the visual appearance of the sediment, was used as a guide for further sampling.In general, the expedition was very successful and all of the research themes formulated in the original proposal will be explored and the objectives met. The project presented here is designed as two integrated sub-projects with the following overarching aims: • To better constrain the model of the Scandinavian Ice Sheet with its global and regional isostatic and eustatic impacts. • To investigate how Baltic in- and outflows have varied over time and how these variation are related to changes in large-scale atmospheric circulation and changing sea levels (threshold depths). • To determine the main mechanisms behind hypoxia-driving processes in the Baltic and to what degree human activities have played a role. Expected outcome It is envisaged that answering these research questions it will allow us to gain totally new scientific insights in a variety of research fields such as e.g. • regional and global issues on the timing and forcing of rapid climate change and sea levels • glacial history of the Scandinavian ice sheet and its inter-action with the climate system • mechanisms behind hypoxia-driving processes in intra-continental type of sea basins The Off- and Onshore Science Party consist of 30 specialist scientists from Europe, USA, Japan, China, Australia and New Zeeland and were selected in a strong international competition. In addition to the Co-chief Scientist Thomas Andrén another two Swedes were selected of which the siliceous microfossil specialist Elinor Andrén is also from Södertörn University. Hence Södertörn University scientists play a leading role in the Science Party.
Publications (10 of 18) Show all publications
Sanyal, A., Larsson, J., van Wirdum, F., Andrén, T., Moros, M., Lönn, M. & Andrén, E. (2022). Not dead yet: Diatom resting spores can survive in nature for several millennia. American Journal of Botany, 67-82
Open this publication in new window or tab >>Not dead yet: Diatom resting spores can survive in nature for several millennia
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2022 (English)In: American Journal of Botany, ISSN 0002-9122, E-ISSN 1537-2197, p. 67-82Article in journal (Refereed) Published
Abstract [en]

PREMISE: Understanding the adaptive capacities of species over long timescales lies in examining the revived recent and millennia old resting spores buried in sediments. We show for the first time the revival, viability and germination rate of resting spores of the diatom Chaetoceros deposited in sub-seafloor sediments from three ages (recent: 0-80 years; ancient: ~1250 (Medieval Climate Anomaly) and ~6600 (Holocene Thermal Maximum) calendar year before present.

METHODS: Recent and ancient Chaetoceros spores were revived to examine their viability and germination rate. Light and scanning electron microscopy and Sanger sequencing was done to identify the species.

KEY RESULTS: We show that ~6600 cal. year BP old Chaetoceros resting spores are still viable and the vegetative reproduction in recent and ancient resting spores vary. The time taken to germinate is three hours to 2-3 days in both recent and ancient spores, but the germination rate of the spores decreased with increasing age. The germination rate of the recent spores was ~41% while that of the ancient spores were ~31% and ~12% for the ~1250 and ~6600 cal. year BP old resting spores. Based on the morphology of the germinated vegetative cells we identified the species as Chaetoceros muelleri var. subsalsum. Sanger sequences of nuclear and chloroplast markers identified the species as Chaetoceros muelleri.

CONCLUSIONS: We identify a unique model system, Chaetoceros muelleri var. subsalsum and show that recent and ancient resting spores of the species buried in sediments in the Baltic Sea can be revived and used for long-term evolutionary studies.

Place, publisher, year, edition, pages
Botanical Society of America, 2022
Keywords
Baltic Sea, Chaetoceros muelleri var. subsalsum, Germination rate, Resting spore concentration, Resurrection ecology
National Category
Botany Ecology
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-46593 (URN)10.1002/ajb2.1780 (DOI)000739921100001 ()34648178 (PubMedID)2-s2.0-85122424760 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 75/2014
Available from: 2021-10-20 Created: 2021-10-20 Last updated: 2022-03-02Bibliographically approved
Hyttinen, O., Quintana Krupinski, N., Bennike, O., Wacker, L., Filipsson, H. L., Obrochta, S., . . . Kotilainen, A. T. (2021). Deglaciation dynamics of the Fennoscandian Ice Sheet in the Kattegat, the gateway between the North Sea and the Baltic Sea Basin. Boreas, 50(2), 351-368
Open this publication in new window or tab >>Deglaciation dynamics of the Fennoscandian Ice Sheet in the Kattegat, the gateway between the North Sea and the Baltic Sea Basin
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2021 (English)In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 50, no 2, p. 351-368Article in journal (Refereed) Published
Abstract [en]

This paper presents an age–depth model based on an ultra-high-resolution, 80-m-thick sedimentary succession from a marine continental shelf basin, the Kattegat. This is an area of dynamic deglaciation of the Fennoscandian Ice Sheet during the Late Pleistocene. The Kattegat is also a transitional area between the saline North Sea and the brackish Baltic Sea. As such, it records general development of currents and exchange between these two systems. Data for the succession were provided through the Integrated Ocean Drilling Program Site M0060. The site indicates onset of deglaciation at c. 18 ka BP and relatively continuous sedimentation until 13 ka BP. At this point, sediments record a hiatus until c. 9–7 ka BP. The uppermost sedimentary unit contains redeposited material, but it is estimated to represent only the last c. 9–7 ka BP. The age–depth model is based on 17 select, radiocarbon-dated samples and is integrated with a set of physical and chemical proxies. The integrated records provide novel constraints on the timing of major palaeoenvironmental changes, such as the transition from glaciomarine proximal to glaciomarine distal and marine conditions, and their connections to known major events and processes in the region and the North Atlantic. Depositional evidence specifically documents connections between the Fennoscandian Ice Sheet behaviour and atmospheric and oceanic warming. Glacial retreat may have also depended on topographic factors such as changes in basin width and depth, linked to relative sea level changes and land uplift. The results indicate an early response of the Fennoscandian Ice Sheet to changing climate, and the ice sheet's possible influence on oceanic circulation during the Late Pleistocene deglaciation.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
National Category
Geology
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-42490 (URN)10.1111/bor.12494 (DOI)000594796000001 ()2-s2.0-85096951400 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 75/2014Swedish Research Council, 826‐2012‐5114Swedish Research Council, 621‐2011‐5090
Available from: 2020-12-08 Created: 2020-12-08 Last updated: 2022-01-20Bibliographically approved
Warnock, J., Andrén, E., Juggins, S., Lewis, J., Ryves, D. B., Andrén, T. & Weckström, K. (2020). A high‐resolution diatom‐based Middle and Late Holocene environmental history of the Little Belt region, Baltic Sea. Boreas (1), 1-16
Open this publication in new window or tab >>A high‐resolution diatom‐based Middle and Late Holocene environmental history of the Little Belt region, Baltic Sea
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2020 (English)In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, no 1, p. 1-16Article in journal (Refereed) Published
Abstract [en]

The large‐scale shifts in the salinity of the Baltic Sea over the Holocene are well understood and have been comprehensively documented using sedimentary proxy records. More recent work has focused on understanding how past salinity fluctuations have affected other ecological parameters (e.g. primary productivity, nutrient content) of the Baltic basin, and salinity changes over key events and over short time scales are still not well understood. The International Ocean Drilling Program Expedition 347 cored the Baltic basin in order to collect basin‐wide environmental records through a glacial–interglacial cycle. Site M0059 is located in the Little Belt between the Baltic Sea and the Atlantic Ocean. A composite splice section from Site M0059 was analysed at a decadal resolution to study changes in salinity, nutrient conditions and other surface water column parameters based on changes in diatom assemblages and on quantitative diatom‐based salinity inferences. A mesotrophic slightly brackish assemblage is seen in the lowermost analysed depths, corresponding to 7800–7500 cal. a BP. An increase in salinity and nutrient content of the water column leads into a meso‐eutrophic brackish phase. The observed salinity increase is rapid, lasting from 7500 to 7150 cal. a BP. Subsequently, the Little Belt becomes oligotrophic and is dominated by tychopelagic diatoms from c. 7100 to c. 3900 cal. a BP. This interval contains some of the highest salinities observed followed by diatom assemblages similar to those of the Northern Atlantic Ocean, composed primarily of cosmopolitan open ocean marine diatoms. A return to tychopelagic productivity is seen from 3850 to 980 cal. a BP. Anthropogenic eutrophication is detected in the last 300 years of the record, which intensifies in the uppermost sediments. These results represent the first decadally resolved record in the region and provide new insight into the transition to a brackish basin and subsequent ecological development.

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
National Category
Environmental Sciences
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-39395 (URN)10.1111/bor.12419 (DOI)000505508500001 ()2-s2.0-85074585844 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 75/2014
Available from: 2019-11-15 Created: 2019-11-15 Last updated: 2022-05-03Bibliographically approved
Bathmann, U., Schubert, H., Andrén, E., Tuomi, L., Radziejewska, T., Kulinski, K. & Chubarenko, I. (2020). Editorial: Living Along Gradients: Past, Present, Future. Frontiers in Marine Science, 6, Article ID 801.
Open this publication in new window or tab >>Editorial: Living Along Gradients: Past, Present, Future
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2020 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, article id 801Article in journal, Editorial material (Refereed) Published
Abstract [en]

The Baltic Sea is a geologically and evolutionarily young part of the coastal ocean that experienced, in its past, several severe environmental changes. In its present state, the Baltic Sea is characterized by both horizontal and vertical gradients of environmental conditions. As a huge estuary, it shows a west to east/south to north surface salinity gradient from 24 in Kattegat to nearly freshwater in the Bothnian Bay. The vertical salinity and oxygen gradients result in stratification which causes hypoxic and sulfidic anoxic conditions in deep basins. These gradient systems are impacted by natural and anthropogenic changes due to physico-chemical driving forces, varying over time and space. Gradient environments produce an imprint on both the structure and function of the biological systems and influence biogeochemical cycling. Besides, coastal seas in general and the Baltic Sea in particular, experience constant and direct influence from land with consequences to matter and energy cycles, biogeochemical interactions, energy fluxes, and sediment dynamics. “Living along gradients: past, present, future” in the Baltic are today’s very important aspects that rise questions like which of the effects we are detecting occur naturally, and which are driven by human activities. Deciphering past environmental changes and their causes provide keys to understand and simulate possible future scenarios, all of which should rise societal awareness and implementation of appropriate marine and coastal policies. Present-day knowledge on the dynamics of gradient systems, on the processes that affect the coastal sea environment, the results of interaction between coastal seas and society, the detection or reconstruction of past and present changes on time scales from inter-annual to millennial, and future change models are summarized here, with the idea to stimulate scientific exchange on most complex questions, addressing them from different perspectives.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2020
Keywords
Baltic Sea, coastal seas, hypoxia, major baltic inflow, eutrophication
National Category
Environmental Sciences
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-39822 (URN)10.3389/fmars.2019.00801 (DOI)000506839400001 ()2-s2.0-85078188539 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 75/2014
Available from: 2020-01-13 Created: 2020-01-13 Last updated: 2022-03-02Bibliographically approved
Andrén, E., van Wirdum, F., Norbäck Ivarsson, L., Lönn, M., Moros, M. & Andrén, T. (2020). Medieval versus recent environmental conditions in the Baltic Proper, what was different a thousand years ago?. Palaeogeography, Palaeoclimatology, Palaeoecology, 555, Article ID 109878.
Open this publication in new window or tab >>Medieval versus recent environmental conditions in the Baltic Proper, what was different a thousand years ago?
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2020 (English)In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 555, article id 109878Article in journal (Refereed) Published
Abstract [en]

A sediment record from the western Gotland Basin, northwestern Baltic Proper, covering the last 1200 years, was investigated for past changes in climate and the environment using diatoms as a proxy. The aim is to compare the environmental conditions reconstructed during Medieval times with settings occurring the last century under influence of environmental stressors like eutrophication and climate change. The study core records more marine conditions in the western Gotland Basin surface waters during the Medieval Climate Anomaly (MCA; 950–1250C.E.), with a salinity of at least 8 psu compared to the present 6.5 psu. The higher salinity together with a strong summer-autumn stratification caused by warmer climate resulted in extensive long-lasting diatom blooms of Pseudosolenia calcar-avis, effectively enhancing the vertical export of organic carbon to the sediment and contributing to benthic hypoxia. Accordingly, our data support that a warm and dry climate induced the extensive hypoxic areas in the open Baltic Sea during the MCA. During the Little ice Age (LIA; 1400–1700C.E.), the study core records oxic bottom water conditions, decreasing salinity and less primary production. This was succeeded during the 20th century, about 1940, by environmental changes caused by human-induced eutrophication. Impact of climate change is visible in the diatom composition data starting about 1975C.E. and becoming more pronounced 2000C.E., visible as an increase of taxa that thrived in stratified waters during autumn blooms typically due to climate warming.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Baltic Sea, Diatoms, Phytoplankton seasonality, Medieval Climate Anomaly, Hypoxia
National Category
Environmental Sciences
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-41235 (URN)10.1016/j.palaeo.2020.109878 (DOI)000552137900020 ()2-s2.0-85086659693 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 34/2013The Foundation for Baltic and East European Studies, 75/2014
Available from: 2020-06-24 Created: 2020-06-24 Last updated: 2020-08-13Bibliographically approved
Jørgensen, B. B., Andrén, T. & Marshall, I. P. (2020). Sub-seafloor biogeochemical processes and microbial life in the Baltic Sea. Environmental Microbiology, 22(5), 1688-1706
Open this publication in new window or tab >>Sub-seafloor biogeochemical processes and microbial life in the Baltic Sea
2020 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 22, no 5, p. 1688-1706Article, review/survey (Refereed) Published
Abstract [en]

The post-glacial Baltic Sea has experienced extreme changes that are archived today in the deep sediments. IODP Expedition 347 retrieved cores down to 100 m depth and studied the climate history and the deep biosphere. We here review the biogeochemical and microbiological highlights and integrate these with other studies from the Baltic seabed. Cell numbers, endospore abundance and organic matter mineralization rates are extremely high. A 100-fold drop in cell numbers with depth results from a small difference between growth and mortality in the ageing sediment. Evidence for growth derives from a D:L amino acid racemization model, while evidence for mortality derives from the abundance and potential activity of lytic viruses. The deep communities assemble at the bottom of the bioturbated zone from the founding surface community by selection of organisms suited for life under deep sediment conditions. The mean catabolic per-cell rate of microorganisms drops steeply with depth to a life in slow-motion, typical for the deep biosphere. The subsurface life under extreme energy limitation is facilitated by exploitation of recalcitrant substrates, by biochemical protection of nucleic acids and proteins, and by repair mechanisms for random mismatches in DNA or damaged amino acids in proteins. This article is protected by copyright. All rights reserved.

Place, publisher, year, edition, pages
Society for Applied Microbiology, 2020
National Category
Environmental Sciences
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-40096 (URN)10.1111/1462-2920.14920 (DOI)000510497600001 ()31970880 (PubMedID)2-s2.0-85078859648 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 75/2014Swedish Research Council, 2012‐5114Danish National Research Foundation, 104
Note

Also funding: Det Frie Forskningsråd. Grant Number: #7014‐00196

Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2022-03-02Bibliographically approved
Norbäck Ivarsson, L., Andrén, T., Moros, M., Andersen, T. J., Lönn, M. & Andrén, E. (2019). Baltic Sea Coastal Eutrophication in a Thousand Year Perspective. Frontiers in Environmental Science, 7, Article ID 88.
Open this publication in new window or tab >>Baltic Sea Coastal Eutrophication in a Thousand Year Perspective
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2019 (English)In: Frontiers in Environmental Science, E-ISSN 2296-665X, Vol. 7, article id 88Article in journal (Refereed) Published
Abstract [en]

Sediment cores from three sites along the east-coast of Sweden, north-western Baltic Proper, have been studied with respect to lithologies, geochemistry and diatom assemblages to trace and date early human impact with emphasis on nutrient discharge. The three sites Bråviken, Himmerfjärden and Ådfjärden, have been impacted to various degree during the last millennia by multiple stressors like excessive nutrient discharge and hazardous substances, leading to coastal hypoxia, eutrophication and pollution. These stressors are mainly caused by drivers in the drainage area as increased human population, changed land use and point sources as industries and a sewage treatment plant. Even though their detailed history differs, the results show similar general patterns for all three sites. We find no evidence in our data from the coastal zone supporting the hypothesis that the extensive areal distribution of hypoxia in the open Baltic Sea during the Medieval Climate Anomaly was caused by human impact. Timing of the onset of man-made eutrophication, as identified from d15N and changes in diatom composition, differs between the three sites, reflecting the site specific geography and local environmental histories of these areas. The onset of eutrophication dates to 1800 CE in Bråviken and Himmerfjärden areas, and to 1900 CE in the less urban area of Ådfjärden. We conclude that the recorded environmental changes during the last centuries are unique in a thousand year perspective.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
Keywords
diatom stratigraphy, stable nitrogen isotopes, hypoxia, Medieval Climate Anomaly, NW Baltic proper, nutrient discharge
National Category
Environmental Sciences
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-38479 (URN)10.3389/fenvs.2019.00088 (DOI)000471701600001 ()2-s2.0-85068480167 (Scopus ID)1562/3.1.1/2013 (Local ID)1562/3.1.1/2013 (Archive number)1562/3.1.1/2013 (OAI)
Funder
The Foundation for Baltic and East European Studies, 34/2013Stockholm County CouncilThe Foundation for Baltic and East European Studies, 75/2014
Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2022-03-02Bibliographically approved
Stepanova, A., Obrochta, S., Quintana Krupinski, N. B., Hyttinen, O., Kotilainen, A. & Andrén, T. (2019). Late Weichselian to Holocene history of the Baltic Sea as reflected in ostracod assemblages. Boreas, 48(3), 761-778
Open this publication in new window or tab >>Late Weichselian to Holocene history of the Baltic Sea as reflected in ostracod assemblages
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2019 (English)In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 48, no 3, p. 761-778Article in journal (Refereed) Published
Abstract [en]

The study presents the first description and analysis of ostracod records from three sites cored in different parts of the Baltic Sea during the IODP Expedition 347, Baltic Sea Paleoenvironment. Our data present the first high-resolution ostracod records from the Late Weichselian and Holocene sediments collected across the Baltic Sea Basin. Using published data on modern ostracod species ecology of the Baltic Sea, we were able to provide ostracod-based palaeoreconstructions of the history of the region. The stratigraphical framework for the sites is based on radiocarbon-based age models. The three studied sites reveal different ostracod assemblage successions that reflect environmental changes in the study area. Site M0060, located in the Kattegat area, contains the oldest ostracod assemblages that document a marine environment with very high sedimentation rates during the most recent deglaciation. Between ~13 000 and 7500 cal. a BP a modern-like near-shore environment developed. Site M0059 in the southwestern Baltic Sea, Little Belt area, contains assemblages reflecting the transition from a freshwater lake to the brackish Littorina Sea between ~7500 and 7300 cal. a BP. Site M0063 is the deepest location in the central Baltic, Landsort Deep, and yielded very limited ostracod data, but comparison with our organic carbon data allowed us to distinguish the Yoldia Sea, Ancylus Lake and Littorina Sea intervals. The ostracod record correlates well with the organic carbon record with alternation between periods of hypoxia and periods of low oxygen that still supported ostracods.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
National Category
Geology
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-37621 (URN)10.1111/bor.12375 (DOI)000484327000014 ()2-s2.0-85060756108 (Scopus ID)2207/3.1.1/2014 (Local ID)2207/3.1.1/2014 (Archive number)2207/3.1.1/2014 (OAI)
Funder
The Foundation for Baltic and East European Studies, 75/2014
Available from: 2019-02-08 Created: 2019-02-08 Last updated: 2022-05-03Bibliographically approved
Mhatre, S. S., Kaufmann, S., Marshall, I. P., Obrochta, S., Andrén, T., Jørgensen, B. B. & Lomstein, B. A. (2019). Microbial biomass turnover times and clues to cellular protein repair in energy-limited deep Baltic Sea sediments. FEMS Microbiology Ecology, 95(6), Article ID fiz068.
Open this publication in new window or tab >>Microbial biomass turnover times and clues to cellular protein repair in energy-limited deep Baltic Sea sediments
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2019 (English)In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 95, no 6, article id fiz068Article in journal (Refereed) Published
Abstract [en]

The discovery of active microbial life deeply buried beneath the seafloor has opened important questions: how do microorganisms cope with extreme energy limitation, what is their metabolic activity, and how do they repair damages to essential biomolecules? We used a D:L-amino acid model to calculate microbial biomass turnover times. We used a metagenome and metatranscriptome analysis to investigate the distribution of the gene that encodes Protein-L-iso aspartate(D-aspartate) O-methyltransferase (PCMT), an enzyme which recognizes damaged L-isoapartyl and D-aspartyl residues in proteins and catalyzes their repair. Sediment was retrieved during the Integrated Ocean Drilling Program (IODP) Expedition 347 from Landsort Deep and the Little Belt in the Baltic Sea. The study covers the period from the Baltic Ice Lake ca. 13 000 years ago to the present. Our results provide new knowledge on microbial biomass turnover times and protein repair in relation to different regimes of organic matter input. For the first time, we show that the PCMT gene was widely distributed and expressed among phylogenetically diverse groups of microorganisms. Our findings suggest that microbial communities are capable of repairing D-amino acids within proteins using energy obtained from the degradation of a mixture of labile compounds in microbial necromass and more recalcitrant organic matter.

Place, publisher, year, edition, pages
Oxford University Press, 2019
Keywords
D:L-amino acid model, Glacial-Holocene transition, Protein-L-isoaspartate(D-aspartate) O-methyltransferase, biomass turnover times, marine deep biosphere, microbial necromass, organic matter diagenesis, protein repair
National Category
Environmental Sciences
Research subject
Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-38303 (URN)10.1093/femsec/fiz068 (DOI)000474762800012 ()31095297 (PubMedID)2-s2.0-85067268290 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 294200The Foundation for Baltic and East European Studies, 75/2014
Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2022-03-02Bibliographically approved
van Wirdum, F., Andrén, E., Wienholz, D., Kotthoff, U., Moros, M., Fanget, A.-S. -., . . . Andrén, T. (2019). Middle to late holocene variations in salinity and primary productivity in the central Baltic Sea: A multiproxy study from the landsort deep. Frontiers in Marine Science, 6, Article ID 51.
Open this publication in new window or tab >>Middle to late holocene variations in salinity and primary productivity in the central Baltic Sea: A multiproxy study from the landsort deep
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2019 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, article id 51Article in journal (Refereed) Published
Abstract [en]

Anthropogenic forcing has led to an increased extent of hypoxic bottom areas in the Baltic Sea during recent decades. The Baltic Sea ecosystem is naturally prone to the development of hypoxic conditions due to its geographical, hydrographical, geological, and climate features. Besides the current spreading of hypoxia, the Baltic Sea has experienced two extensive periods of hypoxic conditions during the Holocene, caused by changing climate conditions during the Holocene Thermal Maximum (HTM; 8–4.8 cal ka BP) and the Medieval Climate Anomaly (MCA; 1–0.7 cal ka BP). We studied the variations in surface and bottom water salinity and primary productivity and their relative importance for the development and termination of hypoxia by using microfossil and geochemical data from a sediment core retrieved from the Landsort Deep during IODP Expedition 347 (Site M0063). Our findings demonstrate that increased salinity was of major importance for the development of hypoxic conditions during the HTM. In contrast, we could not clearly relate the termination of this hypoxic period to salinity changes. The reconstructed high primary productivity associated with the hypoxic period during the MCA is not accompanied by considerable increases in salinity. Our proxies for salinity show a decreasing trend before, during and after the MCA. Therefore, we suggest that this period of hypoxia is primarily driven by increasing temperatures due to the warmer climate. These results highlight the importance of natural climate driven changes in salinity and primary productivity for the development of hypoxia during a warming climate.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
Keywords
paleoceanography, hypoxia, geochemistry, diatoms, foraminifera, palynomorphs, IODP Expedition 347
National Category
Climate Research
Research subject
Baltic and East European studies; Environmental Studies
Identifiers
urn:nbn:se:sh:diva-37781 (URN)10.3389/fmars.2019.00051 (DOI)000462668800001 ()2-s2.0-85061721558 (Scopus ID)1562/3.1.1/2013 (Local ID)1562/3.1.1/2013 (Archive number)1562/3.1.1/2013 (OAI)
Funder
The Foundation for Baltic and East European Studies, 34/2013The Foundation for Baltic and East European Studies, 75/2014Swedish Research Council, 2012-5114
Note

This research was supported by the Foundation for Baltic and East European Studies (Grants 1562/3.1.1/2013 and 2207/3.1.1/2014), the Swedish Research Council (Grant 826- 2012-5114), the Carlsberg Foundation (IVAR-347 project) and Geocenter Denmark (DAN-IODP-SEIS project), the Independent Research Fund Denmark (Grant 7014-00113B, G-Ice), and the German Research Foundation (DFG, projects Ko3944/6-1 and Ko3944/8–1).

Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2022-03-02Bibliographically approved
Principal InvestigatorAndrén, Thomas
Co-InvestigatorAndrén, Elinor
Coordinating organisation
Södertörn University
Funder
Period
2015-01-01 - 2017-12-31
Keywords [sv]
Östersjö- och Östeuropaforskning
Keywords [en]
Baltic and East European studies
National Category
Environmental Sciences
Identifiers
DiVA, id: project:1792Project, id: 75/2014_OSS

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