| 61. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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Distribution of the putative invasive species Nonionella sp. T1 in the Gullmar Fjord – What is its potential contribution to biogeochemical cycles?
- 2023
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Ingår i: International Congress FORAMS2023, Perugia, Italy 25-30th June 2023.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Benthic foraminifera, both fossil and living, have been extensively studied in the seasonally hypoxic Gullmar Fjord (Sweden) for decades to decipher hydrographic changes and ecological status. In 2011, a non-indigenous species named Nonionella sp. T1 was discovered in the fjord for the first time. Here, we aim at evaluating its putative invasive behavior and life strategies by combining assemblage analyses of living foraminifera along a fjord transect of surface sediment (0-3 cm) together with four longer sediment cores (0-5 cm) from two stations at 51 m and 117 m water depth. Our results showed that Nonionella sp. T1 collected in the surface sediment in September 2021 and 2022, was present in almost all the transect samples. This species dominated the living foraminiferal assemblages with an abundance between 15 and 72 %, at seven of the eight sites visited. The highest relative and absolute abundances were noted between 39 and 78 m water depth, proximal to the fjord mouth, with a reduced presence towards the deepest station and the fjord head. However, Nonionella sp. T1 was completely absent in the sandy sediments at the shallowest station (1 m water depth). Sediment cores collected in November 2017 and May 2022 revealed that Nonionella sp. T1 exhibited higher abundance at 51 m water depth compared to 117 m. In a previous study, higher densities were observed at the station 51 m below the oxygenated sediment zone (< 2 mm depth), where high nitrate concentrations in pore waters were measured (2017 data). The authors demonstrated that Nonionella sp. T1 respires nitrate and the pool of specimens denitrifies up to 50 % – 100 % of the nitrate in sediment porewaters, revealing its non-negligible contribution to benthic denitrification. The 10-fold higher abundance of Nonionella sp. T1 recorded in 2022 (compared to 2017) supports previous hypotheses about their invasive character and alerts about their important role in the nitrogen cycle of the Gullmar Fjord. The results of this study highlight the need for continued monitoring of this invasive species, its spreading dynamics and ecological/biogeochemical impacts.
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| 62. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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Spreading of an alien benthic foraminifer in the North Sea: a reason to be worried?
- 2023
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Ingår i: International Congress FORAMS2023, Perugia, Italy, 25-30th June. - Perugia, Italy : Micropress Europe & The Grzybowski Foundation.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the Skagerrak-Kattegat (eastern North Sea), the alien benthic foraminifer Nonionella sp. T1 (previously referred to as “Nonionella stella”) was reported for the first time in 2011 and 2012 in the Swedish and southern Norwegian fjords, respectively. Based on dated sediment cores its first occurrence can be traced back to the 1980s in the Gullmar Fjord, to the 2000s in the Öresund and to 2010 in the Oslofjord. Since then, Nonionella sp T1 has spread all over the Kattegat and coastal Skagerrak, according to sampling campaigns performed between 2016 and 2022. The species is now highly abundant in the entire Kattegat, including the Öresund, as well as in fjord mouths of the seasonally hypoxic Gullmar Fjord, the oxic Hakefjord and the long-term polluted Idefjord as demonstrated by molecular and morphospecies data. At the same time, Nonionella sp T1 is rare to absent in the Baltic Sea, Skagerrak deep basin and in deep fjords of western and northern Norway. This study shows some preliminary results on the species’ present distribution in the study area and raises questions about the driving factors and potential effects on the local biodiversity.
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| 63. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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The Little Ice Age: evidence from a sediment record in Gullmar Fjord, Swedish west coast : The Little Ice Age in a sediment record from Gullmar Fjord
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 1275-1290
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the climatic and environmental changes during the last millennium in NE Europe based on a ca. 8-m long high-resolved and well-dated marine sediment record from the deepest basin of Gullmar Fjord (SW Sweden). According to the 210Pb- and 14C-datings, the record includes the period of the late Holocene characterised by anomalously cold summers and well-known as the Little Ice Age (LIA). Using benthic foraminiferal stratigraphy, lithology, bulk sediment geochemistry and stable carbon isotopes we reconstruct various phases of the cold period, identify its timing in the study area and discuss the land–sea interactions occurring during that time. The onset of the LIA is indicated by an increase in cold-water foraminiferal species Adercotryma glomerata at 1350AD. The first phase of the LIA was characterised by a stormy climate and higher productivity, which is indicated by a foraminiferal unit of Nonionella iridea and Cassidulina laevigata. Maximum abundances of N. iridea probably mirror a short and abrupt warming event at 1600 AD. It is likely that due to land use changes in the second part of the LIA there was an increased input of terrestrial organic matter to the fjord, which is indicated by lighter 13C values and an increase of detritivorous and omnivorous species such as Textularia earlandi and Eggerelloides scaber. The climate deterioration during the climax of the LIA (1675–1704 AD), as suggested by the increase of agglutinated species, presence of Hyalinea balthica, and a decline of N. iridea may have driven the decline in primary productivity during this time period.
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| 64. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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Tracing winter temperatures over the last two millennia using a north-east Atlantic coastal record
- 2018
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 14:7, s. 1097-1118
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Tidskriftsartikel (refereegranskat)abstract
- We present 2500 years of reconstructed bottom water temperatures (BWT) using a fjord sediment archive from the north-east Atlantic region. The BWT represent winter conditions due to the fjord hydrography and the associated timing and frequency of bottom water renewals. The study is based on a ca. 8 m long sediment core from Gullmar Fjord (Sweden), which was dated by Pb-210 and AMS C-14 and analysed for stable oxygen isotopes (delta O-18) measured on shallow infaunal benthic foraminiferal species Cassidulina laevigata d'Orbigny 1826. The BWT, calculated using the palaeotemperature equation from McCorkle et al. (1997), range between 2.7 and 7.8 degrees C and are within the annual temperature variability that has been instrumentally recorded in the deep fjord basin since the 1890s. The record demonstrates a warming during the Roman Warm Period (similar to 350 BCE-450 CE), variable BWT during the Dark Ages (similar to 450-850 CE), positive BWT anomalies during the Viking Age/Medieval Climate Anomaly (similar to 850-1350 CE) and a long-term cooling with distinct multidecadal variability during the Little Ice Age (similar to 1350-1850 CE). The fjord BWT record also picks up the contemporary warming of the 20th century (presented here until 1996), which does not stand out in the 2500-year perspective and is of the same magnitude as the Roman Warm Period and the Medieval Climate Anomaly.
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| 65. |
- Polovodova, Irina, 1980, et al.
(författare)
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Detailing the Little Ice Age on the Swedish west coast: a multi-proxy study of a sediment record from Gullmar Fjord
- 2014
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Ingår i: Marchant, M . & Hromic, T. (eds . ) 201 4 . Internation al Symposium on Foraminifera Forams 2014, Chile, 19 – 24 January 2014 , Abstract Volume . Grzybowski Foundation Special Publication, 20 , 124 pp.. - 9788388927355 ; , s. 38-39
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Gullmar Fjord, on the west coast of Sweden, represents a high-resolution environmental archive due to high sedimentation rates, low bioturbation and negligible tidal activity. In this study we attempt to detail the climatic and environmental changes in NE Europe during the last millennium by using a ca. 8-m long well dated sediment record from the deep fjord basin. According to the 14C-datings, the record includes the period of the late Holocene characterised by anomalously cold summers and well known as the Little Ice Age (LIA). Using a high-resolution stratigraphy of benthic foraminifera and dinoflagellate cysts along with lithology, bulk sediment geochemistry and foraminiferal δ13C we identify the timing of the cold period, reconstruct its various phases, and discuss the land-sea interactions occurring in the study area during that time. The onset of the LIA is indicated at ~1350 A.D by an increase in abundances of cold-water foraminifer Adercotryma glomerata and the cryophilic dinoflagellate cyst Islandinium cf. cezare. The first phase of the LIA was characterised by a stormy climate and higher productivity, as suggested by a foraminiferal assemblage of Nonionella iridea and Cassidulina laevigata. The hypothesis of higher productivity is supported by the isotopic and the dinoflagellate cyst records, which show a shift towards more negative δ13C values, and a marked increase in the microreticulate cysts of Gymnodinium nolleri at the onset of the LIA. The dinoflagellate species G. nolleri becomes relict towards the LIA termination and could be also associated with lower surface water temperatures at that time. It is likely that due to land use changes in the second part of the LIA there was an increased input of terrestrial organic matter to the fjord, which is indicated by lighter δ13C values and an increase of detritivorous and omnivorous foraminiferal species such as Textularia earlandi and Eggerelloides scaber. The climate deterioration during the climax of the LIA (1675-1704 A.D.) may have driven a decline in primary productivity, as suggested by the increase of agglutinated foraminiferal species, the presence of Hyalinea balthica, and a decline of N. iridea during that time.
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| 66. |
- Polovodova, Irina, 1980, et al.
(författare)
-
High resolution foraminiferal stratigraphy and climatic variations over the last ca. 2500 years: Evidence from Gullmar Fjord and Skagerrak-Kattegat area
- 2010
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Ingår i: International Symposium on Foramininfera Forams 2010, September 5-10th, 2010, University of Bonn, Germany. ; , s. 164-164
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sediment cores from Gullmar Fjord (Swedish west coast) and the Skagerrak-Kattegat area were analysed for benthic foraminifera and stable δ13C isotope data. We obtained high-resolution records encompassing climatic variations over the last 2,500 years. In Gullmar Fjord, the δ13C curve shows distinctly negative values during Roman, Medieval, and Recent warm periods, but also during the Little Ice Age. Benthic foraminifera show profound changes in the record characterized by the decline of Nonionella iridea, Adercotryma glomerata and Cassidulina laevigata and the establishment of Hyalinea balthica and Stainforthia fusiformis. Roman and Medieval warm periods are characterized by similar foraminiferal assemblages, whereas Little Ice Age and Recent warming show significantly different faunal composition. The data are compared to records from Skagerrak and Kattegat in order to see if there are regional signals for these climatic events.
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| 67. |
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| 68. |
- Polovodova, Irina, 1980, et al.
(författare)
-
The benthic foraminiferal record of the Medieval Warm Period and the recent warming in the Gullmar Fjord, Swedish west coast : Medieval Warm Period and the recent warming in the Gullmar Fjord
- 2011
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Ingår i: Marine Micropaleontology. - : Elsevier BV. - 0377-8398. ; 81, s. 96-106
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Tidskriftsartikel (refereegranskat)abstract
- A high-resolution study of benthic foraminiferal assemblages was performed on a ca. eight metre long sediment core from Gullmar Fjord on the west coast of Sweden. The results of 210Pb- and AMS 14C-datings show that the record includes the two warmest climatic episodes of the last 1500 years: the Medieval Warm Period (MWP) and the recent warming of the 20th century. Both periods are known to be anomalously warm and associated with positive NAO winter indices. Benthic foraminiferal successions of both periods are compared in order to find faunal similarities and common denominators corresponding to past climate changes. During the MWP, Adercotryma glomerata, Cassidulina laevigata and Nonionella iridea dominated the assemblages. Judging from dominance of species sensitive to hypoxia and the highest faunal diversity for the last ca. 2400 years, the foraminiferal record of the MWP suggests an absence of severe low oxygen events. At the same time, faunas and δ13C values both point to high primary productivity and/or increased input of terrestrial organic carbon into the fjord system during the Medieval Warm Period. Comparison of the MWP and recent warming revealed different trends in the faunal record. The thin-shelled foraminifer N. iridea was characteristic of the MWP, but became absent during the second half of the 20th century. The recent Skagerrak–Kattegat fauna was rare or absent during the MWP but established in Gullmar Fjord at the end of the Little Ice Age or in the early 1900s. Also, there are striking differences in the faunal diversity and absolute abundances of foraminifera between both periods. Changes in primary productivity, higher precipitation resulting in intensified land runoff, different oxygen regimes or even changes in the fjord's trophic status are discussed as possible causes of these faunal differences.
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| 69. |
- Powers, Christopher, et al.
(författare)
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Two canonically aerobic foraminifera express distinct peroxisomal and mitochondrial metabolisms
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Certain benthic foraminifera thrive in marine sediments with low or undetectable oxygen. Potential survival avenues used by these supposedly aerobic protists include fermentation and anaerobic respiration, although details on their adaptive mechanisms remain elusive. To better understand the metabolic versatility of foraminifera, we studied two benthic species that thrive in oxygen-depleted marine sediments. Here we detail, via transcriptomics and metatranscriptomics, differential gene expression of Nonionella stella and Bolivina argentea, collected from Santa Barbara Basin, California, USA, in response to varied oxygenation and chemical amendments. Organelle-specific metabolic reconstructions revealed these two species utilize adaptable mitochondrial and peroxisomal metabolism. N. stella, most abundant in anoxia and characterized by lack of food vacuoles and abundance of intracellular lipid droplets, was predicted to couple the putative peroxisomal beta-oxidation and glyoxylate cycle with a versatile electron transport system and a partial TCA cycle. In contrast, B. argentea, most abundant in hypoxia and contains food vacuoles, was predicted to utilize the putative peroxisomal gluconeogenesis and a full TCA cycle but lacks the expression of key beta-oxidation and glyoxylate cycle genes. These metabolic adaptations likely confer ecological success while encountering deoxygenation and expand our understanding of metabolic modifications and interactions between mitochondria and peroxisomes in protists.
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| 70. |
- Tjörnstrand, Axel, et al.
(författare)
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The incidence rate of pituitary adenomas in western Sweden for the period 2001-2011
- 2014
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Ingår i: European Journal of Endocrinology. - 0804-4643 .- 1479-683X. ; 171:4, s. 519-526
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Tidskriftsartikel (refereegranskat)abstract
- © 2014 European Society of Endocrinology. Objective: The number of studies on the incidence of pituitary adenomas (PAs) is limited. The aim of this study was to evaluate the standardised incidence rate (SIR) of PAs in western Sweden.Design, subjects and methods: Data from adult patients diagnosed with PAs in 2001-2011, living in the Vä stra Götaland County, were collected from the Swedish Pituitary Registry (SPR). In addition, medical records on all patients diagnosed with PAs at the six hospitals in the region were reviewed. In total, 592 patients were included in the study.Age-SIR, given as rate/100 000 inhabitants (95% CI), was calculated using the WHO 2000 standard population as a reference.Results: The total SIRfor PAswas 3.9/100 000 (3.6-4.3); 3.3/100 000 (2.9-3.7) formen and 4.7/100 000 (4.1-5.3) forwomen. Inmen, SIR increasedwith age, while inwomen SIR peaked at 25-34 years, mainly due to prolactinomas. Non-functioning PA (NFPA)was the most common PA (54%, 1.8/100 000 (1.6-2.0)) followed by prolactinomas (32%, 1.6/100 000 (1.3-1.9)), acromegaly (9%, 0.35/100 000 (0.25-0.45)), Cushing'sdisease (4%, 0.18/100 000 (0.11-0.25)) andTSH-producingPA(0.7%, 0.03/100 000 (0.00-0.05)). The proportion of macroadenomas for NFPA was 82%, prolactinomas 37%, GH-producing PA 77%, ACTH-producing PA 28% and TSH-producing PA 100%. The lifetime risk for PAs was 0.27% (0.24-0.31) in men and 0.29% (0.26-0.33) in women.Conclusion: This study provides a reliable estimate on the overall incidence of PAs and confirms an increased incidence of PAs compared with studies conducted in the pre-magnetic resonance imaging era. The lower proportion of prolactinomas compared with previous studies is probably explained by the different criteria used.
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