Kjell Rasmus Bjørklund

• Dolven, Jane & Bjørklund, Kjell Rasmus (2024). Actinomma sogndalensis n. sp. (Radiolaria, Polycystina) an endemic species to the Sognefjord, western Norway. Revue de Micropaleontologie. ISSN 0035-1598. doi: 10.1016/j.revmic.2024.100818. Full text in Research Archive Show summary

  Studies of polycystine radiolarians (marine planktonic protists) have shown that great faunistic differences occur between the different Norwegian fjord systems. Plankton studies by Swanberg and Bjørklund in the early 1980′s identified more than 55 polycystine radiolarian species, including two unidentified forms of Actinomma noted as sp. A and sp. B. The discovery of fully developed adult individuals of the same taxa in plankton material from the Sogndalsfjord in 2010 revealed that the sp. A form in fact was a juvenile stage of the sp. B form. Its general morphologic skeletal structure differs so much from the other local Actinomma species that the whole concept of how to define, and what to include in, this genus has been taken up here for discussion. This new species, described herein as Actinomma sogndalensis, has mainly been found in the Sognefjord, which leads us to conclude that A. sogndalensis might be an example of a real endemic fjord species. Due to the fragility of the latticed cortical shells, only the two thick primary medullary shells are preserved in the sediment. This led us to include a discussion regarding the number of concentric shells and their relevance or usefulness as a taxonomic criterion at the genus level in conjunction with this description of the new species. The genus Actinomma is emended to include species with two or multiple lattice spheres. Cromyechinus is by us still regarded as a junior synonym of Actinomma.

• Ikenoue, Takahito; Bjørklund, Kjell Rasmus; Krabberød, Anders Kristian; Nishino, Shigeto & Wassmann, Paul (2023). Radiolaria and Phaeodaria (siliceous Rhizaria) in south-western and northern Norwegian fjords during late summer 2016: dominant species and biomass in shallow-water assemblages. Polar Research. ISSN 0800-0395. 42. doi: 10.33265/polar.v42.9584. Full text in Research Archive Show summary

  To determine the present-day community composition of siliceous Rhizaria (Radiolaria and Phaeodaria) in Norwegian fjords, plankton tows were conducted in south-western and northern Norwegian fjords in September 2016. The mean total abundance of radiolarians was 306 m^–3 in the Sognefjord complex, which was the southern research site, and, in the north, 945 m^–3 in Malangen and 89 m^–3 in Balsfjord, both above the Arctic Circle. Sticholonche zanclea was the most abundant radiolarian in the Sognefjord complex and Malangen, accounting for 78–100% (mean 89%) of radiolarian abundance. The mean total abundance of phaeodarians was 1554 m^–3 in the Sognefjord complex, 51 m^–3 in Malangen and 11 m^–3 in Balsfjord. Medusetta arcifera was the most abundant phaeodaria in the Sognefjord complex, accounting for >99% of phaeodarian abundance, but was absent in Malangen and Balsfjord, where Protocystis tridens accounted for >96% of phaeodarian abundance. The carbon biomass of S. zanclea and M. arcifera was 188 and 438 µg C m^–3, respectively, which is similar to and 8.6 times higher than, respectively, that of phaeodarians >1 mm in the western North Pacific, suggesting that M. arcifera contributes to organic carbon transport in the Sognefjord complex. Amphimelissa setosa (Nassellaria, Radiolaria), which was a dominant species in the study area in 1982–83, was absent in the present study in all sampled fjords. This could have been caused by the approximately 2 °C increase in water temperature that has occurred since 1990 and can be taken as evidence of a climate-change-associated local temperature rise linked to the warming of advected Atlantic Water.

• Ikenoue, Takahito; Kimoto, Katsunori; Nakamura, Yuriko; Bjørklund, Kjell Rasmus; Kuramoto, Naoki & Ueki, Masaaki [Show all 15 contributors for this article] (2021). New evaluation of species-specific biogenic silica flux of radiolarians (Rhizaria) in the western Arctic Ocean using microfocus X-ray computed tomography. Limnology and Oceanography. ISSN 0024-3590. 66(11), p. 3901–3915. doi: 10.1002/lno.11928. Full text in Research Archive Show summary

  We studied time-series fluxes of radiolarian particles collected by two sediment traps deployed at the eastern (Sta. NAP12t) and western (Sta. CAP12t) sides of the Chukchi Borderland in the Chukchi Sea from 04 October 2012 to 18 September 2013. In order to elucidate the contribution of radiolarian skeletons to the biogenic silica flux, a three-dimensional (3D) imaging technique using microfocus X-ray computed tomography (MXCT) was applied to radiolarian siliceous skeletons. We calculated volumes of individual radiolarian skeletons accurately using a 3D model of them, thereby estimating the mass of silica for each radiolarian species. The time-series fluxes of radiolarian abundance were combined with the mass of radiolarian silica and were transformed to estimate fluxes of radiolarian silica. As a result, we found that the main carrier of radiolarian silica in the western Arctic Ocean was represented by only two species; that is, Amphimelissa setosa (averages: 55.2 wt% at Sta. NAP12t, 70.8 wt% at Sta. CAP12t) and Spongotrochus glacialis (averages: 36.7 wt% at Sta. NAP12t, 23.2 wt% at Sta. CAP12t). The total radiolarian silica flux was usually higher in the eastern side than that in the western side of the Chukchi Borderland. The contribution of radiolarian silica to the biogenic silica flux was less than 10 wt% in general during the sampling duration, but occasionally reached 19.6–34.8 wt% during the open water season. This suggests that not only diatoms but also radiolarians make a significant contribution in driving the silica cycle in the Arctic Ocean.

• Hernández-Almeida, Iván; Bjørklund, Kjell Rasmus; Diz, Paula; Kruglikova, Svetlana B.; Ikenoue, Takahito & Matul, Alexander G. [Show all 8 contributors for this article] (2020). Life on the ice-edge: Paleoenvironmental significance of the radiolarian species Amphimelissa setosa in the northern hemisphere. Quaternary Science Reviews. ISSN 0277-3791. 248, p. 1–17. doi: 10.1016/j.quascirev.2020.106565. Full text in Research Archive
• Ikenoue, Takahito; Bjørklund, Kjell Rasmus; Fujiwara, Amane; Uchimiya, Mario; Kimoto, Katsunori & Harada, Naomi [Show all 7 contributors for this article] (2019). Horizontal and vertical distribution of polycystine radiolarians in the western Arctic Ocean during the late summers of 2013 and 2015. Polar Biology. ISSN 0722-4060. 42(2), p. 285–305. doi: 10.1007/s00300-018-2421-3. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Kruglikova, Svetlana B. & Hammer, Øyvind (2019). The radiolarian fauna during the younger dryas–holocene transition in andfjorden, northern Norway. Polar Research. ISSN 0800-0395. 38. doi: 10.33265/polar.v38.3444. Full text in Research Archive
• Krabberød, Anders Kristian; Orr, Russell; Bråte, Jon; Kristensen, Tom; Bjørklund, Kjell Rasmus & Shalchian-Tabrizi, Kamran (2017). Single cell transcriptomics, mega-phylogeny and the genetic basis of morphological innovations in Rhizaria. Molecular Biology and Evolution (MBE). ISSN 0737-4038. doi: 10.1093/molbev/msx075. Full text in Research Archive Show summary

  The innovation of the eukaryote cytoskeleton enabled phagocytosis, intracellular transport and cytokinesis, and is responsible for the diversity of eukaryotic morphologies. Still, the relationship between phenotypic innovations in the cytoskeleton and their underlying genotype is poorly understood. To explore the genetic mechanism of morphological evolution of the eukaryotic cytoskeleton we provide the first single cell transcriptomes from uncultured, free-living unicellular eukaryotes: the polycystine radiolarian Lithomelissa setosa (Nassellaria) and Sticholonche zanclea (Taxopodida). A phylogenomic approach using 255 genes finds Radiolaria and Foraminifera as separate monophyletic groups (together as Retaria), while Cercozoa is shown to be paraphyletic. Analysis of the genetic components of the cytoskeleton and mapping of the evolution of these to the revised phylogeny of Rhizaria reveal lineage-specific gene duplications and neofunctionalization of α and β tubulin in Retaria, actin in Retaria and Endomyxa, and Arp2/3 complex genes in Chlorarachniophyta. We show how genetic innovations have shaped cytoskeletal structures in Rhizaria, and how single cell transcriptomics can be applied for resolving deep phylogenies and studying gene evolution in uncultured protist species.

• Ikenoue, Takahito; Bjørklund, Kjell Rasmus; Dumitrica, Paulian; Krabberød, Anders Kristian; Kimoto, Katsunori & Matsuno, Kohei [Show all 7 contributors for this article] (2016). Two new living Entactinaria (Radiolaria) species from the Arctic province: Joergensenium arcticum n. sp. and Joergensenium clevei n. sp. Marine Micropaleontology. ISSN 0377-8398. 124, p. 75–94. doi: 10.1016/j.marmicro.2016.02.003. Full text in Research Archive
• Ikenoue, Takahito; Bjørklund, Kjell Rasmus; Kruglikova, S.B.; Onodera, Jonaotaro; Kimoto, K. & Harada, N. (2015). Flux variations and vertical distributions of siliceous Rhizaria (Radiolaria and Phaeodaria) in the western Arctic Ocean: Indices of environmental changes. Biogeosciences. ISSN 1726-4170. 12(6), p. 2019–2046. doi: 10.5194/bg-12-2019-2015. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Hatakeda, Kentaro; Kruglikova, Svetlana B. & Matul, Alexander G. (2015). Amphimelissa setosa (Cleve) (Polycystina, Nassellaria) - A stratigraphic and paleoecological marker of migrating polar environments in the northern hemisphere during the Quaternary. Stratigraphy. ISSN 1547-139X. 12(1), p. 23–37. Full text in Research Archive
• Burridge, Alice K. & Bjørklund, Kjell Rasmus (2014). Inter- and intraspecific morphological variation of three Hexacontium (Radiolaria) species in three southern Norwegian fjords: H. gigantheum, H. pachydermum and H. enthacantum. Marine Micropaleontology. ISSN 0377-8398. 110, p. 72–82. doi: 10.1016/j.marmicro.2013.11.005. Full text in Research Archive
• Dolven, Jane Karine Lønne; Bjørklund, Kjell Rasmus & Itaki, Takuya (2014). Jørgensen’s polycystine radiolarian slide collection and new species. Journal of Micropalaeontology. ISSN 0262-821X. 33(1), p. 21–58. doi: 10.1144/jmpaleo2012-027. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Itaki, Takuya & Dolven, Jane Karine Lønne (2014). Per Theodor Cleve: A short résumé and his radiolarian results from the Swedish Expedition to Spitsbergen in 1898. Journal of Micropalaeontology. ISSN 0262-821X. 33(1), p. 59–93. doi: 10.1144/jmpaleo2012-024. Full text in Research Archive
• Burridge, Alice K.; Bjørklund, Kjell Rasmus; Kruglikova, Svetlana B. & Hammer, Øyvind (2014). Inter- and intraspecific morphological variation of four-shelled Actinomma taxa (Radiolaria) in polar and subpolar regions. Marine Micropaleontology. ISSN 0377-8398. 110, p. 50–71. doi: 10.1016/j.marmicro.2013.10.004. Full text in Research Archive
• Bråte, Jon; Krabberød, Anders Kristian; Dolven, Jane Karine Lønne; Ose, Randi Frida; Kristensen, Tom & Bjørklund, Kjell Rasmus [Show all 7 contributors for this article] (2012). Radiolaria Associated with Large Diversity of Marine Alveolates. Protist. ISSN 1434-4610. 163(5), p. 767–777. doi: 10.1016/j.protis.2012.04.004. Full text in Research Archive Show summary

  We have isolated cells of unculturable radiolarians from marine coastal waters. Individual cells were subjected to single cell whole genome amplification (SCWGA) and gene-targeted PCR. Using this approach we recover a surprisingly large diversity of sequences related to the enigmatic marine alveolate groups 1 and 2 (MALV I and MALV II) that most likely represent intracellular symbionts or parasites of the radiolarian cells. 18S rDNA phylogeny of the MALV sequences reveals 4 distinct clades of radiolarian associates here named Radiolarian Associated Sequences (RAS) 1-4. One clade of both phaeodarian and radiolarian associates and one clade of only phaeodarian associates are also identified. The MALV sequences cluster according to host type, i.e. sequences from associates identified in radiolarians, fish, copepods, ciliates or dinoflagellates are not intermixed but separated into distinct clades. This implies several independent colonizations of host lineages and links a large diversity of MALV to radiolarian-associated species. This demonstrates that radiolarians may be an important reservoir for MALV, making them a key group for understanding the impact of intracellular symbionts on the marine ecosystem. This study shows that applying SCWGA on unculturable cells is a promising approach to study the vast diversity and interactions of intracellular eukaryote organisms.

• Bjørklund, Kjell Rasmus; Kruglikova, S.B. & Anderson, O.R. (2012). Modern incursions of tropical Radiolaria into the Arctic Ocean. Journal of Micropalaeontology. ISSN 0262-821X. 31, p. 139–158. doi: 10.1144/0262-821X11-030. Full text in Research Archive
• Krabberød, Anders Kristian; Bråte, Jon; Dolven, Jane Karine Lønne; Ose, Randi Frida; Klaveness, Dag & Kristensen, Tom [Show all 8 contributors for this article] (2011). Radiolaria Divided into Polycystina and Spasmaria in Combined 18S and 28S rDNA Phylogeny. PLOS ONE. 6(8). doi: 10.1371/journal.pone.0023526. Full text in Research Archive Show summary

  Radiolarians are marine planktonic protists that belong to the eukaryote supergroup Rhizaria together with Foraminifera and Cercozoa. Radiolaria has traditionally been divided into four main groups based on morphological characters; i.e. Polycystina, Acantharia, Nassellaria and Phaeodaria. But recent 18S rDNA phylogenies have shown that Phaeodaria belongs within Cerocozoa, and that the previously heliozoan group Taxopodida should be included in Radiolaria. 18S rDNA phylogenies have not yet resolved the sister relationship between the main Radiolaria groups, but nevertheless suggests that Spumellaria, and thereby also Polycystina, are polyphyletic. Very few sequences other than 18S rDNA have so far been generated from radiolarian cells, mostly due to the fact that Radiolaria has been impossible to cultivate and single cell PCR has been hampered by low success rate. Here we have therefore investigated the mutual evolutionary relationship of the main radiolarian groups by using the novel approach of combining single cell whole genome amplification with targeted PCR amplification of the 18S and 28S rDNA genes. Combined 18S and 28S phylogeny of sequences obtained from single cells shows that Radiolaria is divided into two main lineages: Polycystina (Spumellaria+Nassellaria) and Spasmaria (Acantharia+Taxopodida). Further we show with high support that Foraminifera groups within Radiolaria supporting the Retaria hypothesis.

• Kruglikova, Svetlana B.; Bjørklund, Kjell Rasmus & Hammer, Øyvind (2011). High rank taxa of Polycystina (Radiolaria) as environmental bioindicators. Micropaleontology. ISSN 0026-2803. 57(6), p. 483–489. Full text in Research Archive
• Hernández-Almeida, I.; Bjørklund, Kjell Rasmus; Sierro, F.J.; Filippelli, G.M.; Cacho, I. & Flores, J.A. (2011). A high resolution opal and radiolarian record from the subpolar North Atlantic during the Mid-Pleistocene Transition (1067-779 ka): Palaeoceanographic implications. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. p. 1–22. doi: 10.1016/j.palaeo.2011.05.049. Full text in Research Archive
• Kruglikova, Svetlana B. & Bjørklund, Kjell Rasmus (2010). Invasion of the Modern Polycystina (Euradiolaria) into the Arctic OCean: Paleoecological Aspects. Russian Journal of Biological Invasions. ISSN 2075-1117. 1(2), p. 95–101. Full text in Research Archive
• Boltovskoy, Demetrio; Kling, Stanley A.; Takahashi, Kozo & Bjørklund, Kjell Rasmus (2010). WORLD ATLAS OF DISTRIBUTION OF RECENT POLYCYSTINA (RADIOLARIA). Palaeontologia Electronica. ISSN 1935-3952. 13(3), p. 1–230. Full text in Research Archive
• Kruglikova, Svetlana B.; Bjørklund, Kjell Rasmus; Dolven, Jane Karine Lønne; Hammer, Øyvind & Cortese, G. (2010). High-rank polycystine radiolarian taxa as temperature proxies in the Nordic Seas. Stratigraphy. ISSN 1547-139X. 7(4), p. 265–281. Full text in Research Archive
• Kruglikova, Svetlana B.; Bjørklund, Kjell Rasmus; Hammer, Øyvind & Anderson, O. Roger (2009). Endemism and speciation in polycystine radiolarian genus Actinomma in the Arctic Ocean: Descrition of two new species Actinomma georgii n. sp. and A. turidae n. sp. Marine Micropaleontology. ISSN 0377-8398. 72(1-2), p. 26–48. doi: 10.1016/j.marmicro.2009.02.004. Full text in Research Archive
• Yuasa, Tomoko; Dolven, Jane Karine Lønne; Bjørklund, Kjell Rasmus; Mayama, Shigeki & Takahashi, Osamu (2009). Molecular phylogenetic position of Hexacontium pachydermum Jørgensen (Radioolaria). Marine Micropaleontology. ISSN 0377-8398. 73(1-2), p. 129–134. doi: 10.1016/j.marmicro.2009.08.001. Full text in Research Archive
• Hatakeda, Kentaro & Bjørklund, Kjell Rasmus (2009). Polycystine radiolarian assemblages from IODP Expedition 306 Site U1313 and U1314, a preliminary study. News of Osaka Micropaleontologists. ISSN 0287-0436. 14, p. 91–108. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Dumitrica, Paulian; Dolven, Jane K. & Swanberg, Neil R. (2008). Joergensenium rotatile n. gen., n. sp. (Entactinaria, Radiolaria): its distribution in west Norwegian fjords. Micropaleontology. ISSN 0026-2803. 53(6), p. 457–468. Full text in Research Archive
• Kruglikova, S.B.; Bjørklund, Kjell Rasmus & Zasko, D.N. (2007). Distribution of Polycystina (Euradiolaria) in the Bottom Sediments and Plankton of the Arctic Ocean and Marginal Arctic Seas. Doklady Biological sciences. ISSN 0012-4966. 415, p. 284–287. Full text in Research Archive
• Itaki, Takuya & Bjørklund, Kjell Rasmus (2007). Conjoined radiolarian skeletons (Actinommidae) from the Japan Sea sediments. Micropaleontology. ISSN 0026-2803. 53(5), p. 371–389. Full text in Research Archive
• Kruglikova, S.B.; Bjørklund, Kjell Rasmus & Zasko, D.N. (2007). Distribution of Polycystina (Euradiolaria) in the Bottom Sediments and Plankton of the Arctic Ocean and marginal Arctic Seas. Doklady Rossijskoj akademii estestvennyh nauk. ISSN 1728-1717. 415(2), p. 1–5. Full text in Research Archive
• Itaki, Takuya & Bjørklund, Kjell Rasmus (2007). Bailey's (1856) radiolarian types from the Bering Sea re-examined. Micropaleontology. ISSN 0026-2803. 52(5), p. 449–464. Full text in Research Archive
• Dolven, Jane Karine Lønne; Lindqvist, Charlotte; Albert, Victor A.; Bjørklund, Kjell Rasmus; Yuasa, T. & Takahashi, O. [Show all 7 contributors for this article] (2007). Molecular Diversity of Alveolates Associated with Neritic North Atlantic Radiolarians. Protist. ISSN 1434-4610. 158, p. 65–76. doi: 10.1016/j.protis.2006.07.004. Full text in Research Archive Show summary

  Seven species of polycystine radiolarians and one phaeodarian species were investigated in order to determine the diversity of their associate organisms and their species specificity. Twelve partial 18S ribosomal DNA (rDNA) sequences were obtained showing a high diversity of associates, both within spumellarian and nassellarian radiolarians and among species. Two of the sequences obtained are highly similar to Scrippsiella, a dinoflagellate genus already reported as a symbiont of polycystine radiolarians. Nine of the new 18S rDNA sequences group with various alveolates. Some of these groups include parasites, such as the lethal endoparasite Amoebophrya, while others consist of non-annotated novel organisms found worldwide in various types of marine environments. We also obtained a sequence from a bacillariophytan highly similar to the 18S rDNA of the diatom species Diatoma tenue, which may derive from radiolarian food. Additionally, this is the first study to report on a phaeodarian associate.

• Harris, N.R.; Expedition, Scientists And the IODP & Bjørklund, Kjell Rasmus (2006). Borehole Observatory Installations on IODP Expedition 306 Reconstruct Bottom-Water Temperature Changes in the Norwegian Sea. Scientific Drilling. ISSN 1816-8957. 2, p. 28–31. Full text in Research Archive
• Yuasa, T.; Takahashi, O.; Dolven, Jane Karine Lønne; Mayama, S.; Matsuoka, A. & Honda, D. [Show all 7 contributors for this article] (2006). Phylogenetic position of the small solitary phaeodarians (Radiolaria) based on 18S rDNA sequences by single cell PCR analysis. Marine Micropaleontology. ISSN 0377-8398. 59, p. 104–114. Full text in Research Archive
• Stein, R.; Kanamatsu, T.; Alvarez-Zarikian, C. & Bjørklund, Kjell Rasmus (2006). North Atlantic Paleoceanography: The Last Five Million Years. EOS. ISSN 0096-3941. 87(13). Full text in Research Archive
• Channell, J.E.T.; Sato, T.; Kanamatsu, T.; Stein, R.; Malone, M. & Alvarez-Zarikian, C. [Show all 7 contributors for this article] (2006). IODP Expeditions 303 and 306 Monitor Miocene- Quaternary Climate in the North Atlantic. Scientific Drilling. ISSN 1816-8957. p. 4–10. Full text in Research Archive
• Stepanjants, S.D.; Cortese, G; Kruglikova, S.B. & Bjørklund, Kjell Rasmus (2006). A review of bipolarity concepts: History and examples from Radiolaria and Medusozoa (Cnidaria). Marine Biology Research. ISSN 1745-1000. 2(3), p. 200–241. Full text in Research Archive
• Cortese, Giuseppe; Dolven, Jane Karine Lønne; Bjørklund, Kjell R & Malmgren, B.A. (2005). Late Pleistocene-Holocene radiolarian paleotemperatures in the Norwegian Sea based on Artificial Neural Networks. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. 224, p. 311–332. Full text in Research Archive
• Stepanjants, S.D.; Bjørklund, Kjell Rasmus; Kruglikova, S.B. & Cortese, G (2005). The bipolar distributionof marine organisms with emphasis on Radiolaria and Cnidaria. Russian Academy of Sciences, Zoological Institute. ISSN 0206-0477. 308, p. 99–120. Full text in Research Archive
• Stepanjants, S. D.; Kruglikova, S.B. & Bjørklund, Kjell Rasmus (2004). The Bipolar Distribution of Marine Organisms with Emphasis on Radiolaria and Cnidarians: A New Stage of Research. In Kafanov, A.I (Eds.), General Questions of Biogeography: In Memories of the Academician O.G. Kusakina. Dalʹnauka. ISSN 9785804404490. p. 124–178. Full text in Research Archive
• Stepanjants, S.D.; Kruglikova, S.B.; Bjørklund, Kjell R & Cortese, G (2004). The bioplar distribution of marine organisms with emphasis on Radiolaria and Cnidaria: A step forward. In Kafanov, A.l. (Eds.), Theoretical problems of biogeography. To the memory of academician O.G. Kussakin. Maik Nauka/Interperiodica. Full text in Research Archive
• Cortese, Giuseppe; Bjørklund, Kjell R & Dolven, Jane Karine Lønne (2003). Polycystine Radiolarians in the Greenland-Iceland-Norwegian (GIN) Seas: Species and assemblage distribution. Sarsia. ISSN 0036-4827. 88, p. 65–88. Full text in Research Archive
• Bjørklund, Kjell R & Kruglikova, Svetlana (2003). Polycystine radiolarians in surface sediments in the Arctic Ocean basins and marginal seas. Marine Micropaleontology. ISSN 0377-8398. 49, p. 231–273. Full text in Research Archive Show summary

  ABSTRACT The polycystine radiolarian faunas in the Arctic Ocean, including the adjacent Arctic seas, have been studied in more than 377 surface samples. The deep basins in the Arctic Ocean have revealed 31 polycystine radiolarian species (11 spumellarians and 20 nassellarians). The polycystine radiolarian fauna in the southern Norwegian Sea was introduced from the north Atlantic Ocean ca. 13.400 yrs. B.P. The shallow low arctic marginal sea sediments (Iceland, Barents, and Chukchi Seas) have a strong dominance of Cannobotryidae (79 %, 77 % and 74 % respectively), while the deep Arctic Ocean basins (Nansen, Amundsen, and Makarov Basins) have a dominance of Actinommidae (90 %, 70 %, and 75 %, respectively). The Arctic polycystine radiolarian faunas have a strong affinity with the Norwegian Sea fauna, which supplies the Arctic Ocean with faunal elements that can live, thrive and reproduce there. In the Chukchi Sea the Pacific faunal influence is obvious (41 species), but none of the Pacific species are found in any abundance in the Amerasian Basin. No radiolarian species was found to be endemic to the Arctic Ocean except for a morphotype of Actinomma l. leptoderma, with a round inner sphere, is a possible endemic candidate for the Arctic Ocean. Eight species are found in all of the Central Arctic Basins, and can therefore be referred to as circumpolar species: Actinomma leptoderma leptoderma, A. l. leptoderma (with round middle sphere), A. l. longispina, A. boreale, Spongotrochus glacialis, P. platycephalus, Cycladophora davisiana, and Tholospyris(?) gephyristes, while Amphimelissa setosa probably is the only true arctic radiolarian species.

• Stepanjants, S.D.; Chernova, N.V.; Lajus, J.A. & Bjørklund, Kjell R (2002). The first Russian scientific-fishery expedition (centenary of the Expedition for Fishery Research at the coast of Murman). Russian Journal of Marine Biology. ISSN 1063-0740. 28(4), p. 308–316. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe & Bjørklund, Kjell R (2002). A high-resolution radiolarian derived paleotemperature record for the Late Pleistocene-Holocene in the Norwegian Sea. Paleoceanography. ISSN 0883-8305. 17(4). Full text in Research Archive Show summary

  Polycystine radiolarians are used to reconstruct summer sea surface temperatures (SSST) for the Late Pleistocene-Holocene (600-13,400 14C yrs. BP) in the Norwegian Sea. At 13,200 14C yrs. BP, SSST was close to the average Holocene SSST (~12C). It then gradually dropped to 7.1C in the Younger Dryas. Near the Younger Dryas-Holocene transition (~10,000 14C years BP), SSST increased 5C in about 530 years. Four abrupt cooling events, with temperature drops of up to 2.1C, are recognized during the Holocene: at 9,340, 7,100 (¿8,200 calendar yrs. event¿), 6,400 and 1,650 14C yrs. BP. Radiolarian SSSTs and the isotopic signal from the GISP2 ice core are strongly coupled, stressing the importance of the Norwegian Sea as a mediator of heat/precipitation exchange between the North Atlantic, the atmosphere, and the Greenland ice sheet. Radiolarian and diatom derived SSST display similarities, with the former not showing the recently reported Holocene cooling trend.

• Kruglikova, Svetlana & Bjørklund, Kjell R (2002). Class Sarcodina.In: List of species of free-living invertebrates of Eurasian Arctic seas and adjacent deep waters. Explorations of the Fauna of the Seas. ISSN 0368-007X. 51(59), p. 20–21. Full text in Research Archive
• Dolven, Jane Karine Lønne & Bjørklund, Kjell R (2001). An early Holocene peak occurrence and recent distribution of Rhizoplegma boreale (Radiolaria): A biomarker in the Norwegian sea. Marine Micropaleontology. ISSN 0377-8398. 42, p. 25–44. Full text in Research Archive
• Cortese, Giuseppe & Bjørklund, Kjell R (1999). Radiolarians from the cyclic Messinian diatomites of Falconara (Sicily, Italy). Geodiversitas. ISSN 1280-9659. 21(4), p. 593–624. Full text in Research Archive
• Stepanjants, S.D.; Bjørklund, Kjell R; Chernova, N.V.; Smirnov, I.S. & Lajus, J.A. (1999). Damperen "Andrei Perwoswanniy", et 100 års jubileum. Årbok for Universitetsmuseet i Bergen. ISSN 1893-1944. p. 69–75. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Cortese, G.; Swanberg, Neil R. & Schrader, Hans J (1998). Radiolarian faunal provinces in surface sediments of teh Greenland, Iceland and Norwegian (GIN) Seas. Marine Micropaleontology. ISSN 0377-8398. 35, p. 105–140. Full text in Research Archive
• Cortese, G. & Bjørklund, Kjell Rasmus (1998). The taxonomy of boreal Atlantic Ocean Actinommida (Radiolaria). Micropaleontology. ISSN 0026-2803. 44(2), p. 149–160. Full text in Research Archive
• Cortese, G. & Bjørklund, Kjell Rasmus (1998). Morphometry and taxonomy of Hexacontium species from western Norwegian fjords. Micropaleontology. ISSN 0026-2803. 44(2), p. 161–172. Full text in Research Archive
• Cortese, G. & Bjørklund, Kjell Rasmus (1997). The morphometric variation of Actinomma boreale (Radiolaria) in Atlantic boreal waters. Marine Micropaleontology. ISSN 0377-8398. 29, p. 271–282. Full text in Research Archive
• Paverd, Pieter J. van de & Bjørklund, Kjell Rasmus (1996). Preservation and density of Late Quaternary Radiolaira in piston-cores from the Banda Sea, Eastern Indonesia. Revista Española de Micropaleontología. ISSN 0556-655X. XXVIII(3), p. 139-152–139-152. Full text in Research Archive
• Ciesielski, P.F. & Bjørklund, Kjell Rasmus (1995). Ecology, morphology, startigraphy and the paleoceanographic significance of Cycladophora davisiana. Part II: Startigraphy in the North Atlantic (DSDP Site 609) and Labrador Sea (ODP Site 646B). Marine Micropaleontology. ISSN 0377-8398. 25, p. 67–86. Full text in Research Archive
• Bjørklund, Kjell Rasmus & Ciesielski, P.F. (1994). Ecology, morphology, and the paleoceanographic significance of Cycladophora davisiana. Party I: Ecology and morphology. Marine Micropaleontology. ISSN 0377-8398. 24, p. 71–88. Full text in Research Archive
• Estep, K.W.; Bjørklund, Kjell Rasmus; Dale, T.; Heimdal, B.R.; Hertum, A.J.W. van & Hill, D. [Show all 10 contributors for this article] (1992). Deus Creavit; Linneaus Disposuit: An international effort to create a catalogue and expert system for the identification of protistan species. Sarsia. ISSN 0036-4827. 77, p. 275–285. Full text in Research Archive

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• Bjørklund, Kjell Rasmus & Kruglikova, S.B. (2011). Who told you that the Gulf Stream has stoped? The Radiolaria do not! Norsk Geologisk Forening Medlemsblad. 1, p. 7–8. Full text in Research Archive Show summary

• Bråte, Jon; Krabberød, Anders Kristian; Dolven, Jane Karine Lønne; Ose, Randi Frida; Kristensen, Tom & Bjørklund, Kjell Rasmus [Show all 7 contributors for this article] (2010). Diversity of unculturable Radiolaria and their symbionts revealed by 18S rDNA phylogeny. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Kruglikova, Svetlana B.; Anderson, O. Roger & Hammer, Øyvind (2009). New species and radiolarian assemblages in the Arctic OCean. Full text in Research Archive
• Boltovskoy, Demetrio; Kling, Stanley A.; Takahashi, Kozo & Bjørklund, Kjell Rasmus (2009). World atlas of distribution of Recent Polycystinea (Radiolaria). Full text in Research Archive
• Kruglikova, Svetlana B.; Bjørklund, Kjell Rasmus & Anderson, O. Roger (2009). Evolution of communities and recent speciation of Radiolaria-Polycystina of the Arctic Ocean. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Itaki, Takuya & Dolven, Jane Karine Lønne (2009). Per Theodor Cleve - a pioneer in planktonology. Full text in Research Archive
• Takahashi, Osamu; Yuasa, Tomoko; Dolven, Jane Karine Lønne; Bjørklund, Kjell Rasmus & Mayama, Shigeki (2009). Molecular phylogenetic position of Hexacontium pachydermum Jørgensen. Full text in Research Archive
• Dolven, Jane Karine Lønne; Bjørklund, Kjell Rasmus & Itaki, Takuya (2009). Eugen Honoratus Jørgensen (1862-1938) - a botanist with a passion for radiolarians. Full text in Research Archive
• Bjørklund, Kjell Rasmus & Kruglikova, Svetlana (2008). Polycystina (Euradiolaria) in the Arctic Ocean: Evolution and speciation. Full text in Research Archive
• Bjørklund, Kjell Rasmus (2008). Radiolaria. In Gornitz, Vivian (Eds.), Encyclopedia of Paleoclimatology and Ancient Environments. Radiolaria. Springer Science+Business Media B.V.. ISSN 9781402045516. p. 869–871. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Kruglikova, Svetlana & Hatakeda, Kentaro (2007). Amphimelissa setosa (Polycystina, Nassellaria), its first occurrence, its stratigraphy and importance as a paleoecological signal in the north Atlantic. Full text in Research Archive
• Kruglikova, S.B. & Bjørklund, Kjell Rasmus (2007). Polycystina (Euradiolaria) from the recent sediments of the Arctic Ocean and adjacent seas. Full text in Research Archive
• Dolven, J.K.; Lindquist, C.; Albert, V.A.; Bjørklund, Kjell Rasmus; Yuasa, T. & Takahashi, O. [Show all 7 contributors for this article] (2006). Putative symbiotic and parasitic alveolates in polycystine radiolarians and phaeodarians from Norwegian fjords. Full text in Research Archive
• Stein, R.; Kanamatsu, T.; Alvarez-Zarikian, C.; Expedition, Scientists And the IODP & Bjørklund, Kjell Rasmus (2006). Late Neogene/Quaternary North Atlantic paleoceanography (IODP Expedition 306). Full text in Research Archive
• Boltovskoy, D.; Bjørklund, Kjell Rasmus; Kling, S.A. & Takahashi, K. (2006). WoRaDD (World Radiolarian Distributional Database):A worldwide compilation of all available recent radiolarian distributional and taxonomic data (Abstract p 42). Full text in Research Archive
• Dolven, J.K.; Lindquist, C.; Albert, V.A. & Bjørklund, Kjell Rasmus (2006). A diversity of radiolarian symbionts and parasites revealed by small subunit ribosomal DNA sequences (Abstract p.41. Full text in Research Archive
• Yuasa, T.; Takahashi, K; Dolven, J.K.; Mayama, S.; Matsuoka, A. & Honda, D. [Show all 7 contributors for this article] (2006). Phaeodarians found a home? Molecular phylogenetic study of Phaeodaria (Abstract p. 141). Full text in Research Archive
• Kruglikova, S.B. & Bjørklund, Kjell Rasmus (2006). Peculiar polycystine radiolarian assemblages in Recent bottom sediments from the Arctic and Arctic-Boreal provinces (Abstract p. 78). Full text in Research Archive
• Itaki, T. & Bjørklund, Kjell Rasmus (2006). "Twin skeletons" in actinommid radiolarians in the Japan Sea (Abstract p. 71). Full text in Research Archive
• Kruglikova, S.B. & Bjørklund, Kjell R (2005). Radiolarians from the surface layer of the high latitude deepwater bottom sediments of the Arctic. Full text in Research Archive
• Kruglikova, S.B. & Bjørklund, Kjell R (2005). Basic pecularity of the Radiolaria-Polycystina assemblages of the Arctic and Arctic-Boreal area of the Ocean. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe; Bjørklund, Kjell R & Malmgren, B.A. (2005). Paleoclimatic changes in the Norwegian Sea over the last 16.000 yrs. BP based on subfossil radiolarians. Full text in Research Archive
• Bjørklund, Kjell R; Kruglikova, Svetlana; Dolven, Jane Karine Lønne & Cortese, Giuseppe (2005). Radiolarians in the high Northern Atlantic and the Arctic Ocean: Distribution in space and time. Full text in Research Archive
• Bjørklund, Kjell Rasmus; Dolven, J.K.; Takahashi, O.; Yuasa, T. & Mayama, S. (2004). Radiolarian DNA: a progress report. Full text in Research Archive
• Bjørklund, Kjell R & Kruglikova, S.B. (2004). Composition, biogeographical analysis, ways of migration of Radiolarians to the Arctic Basin. Full text in Research Archive Show summary

  60 radiolarian species (14 Spumellaria and 44 Nassellaria) have been identified in the surface layer of the bottom sediments of the Arctic Ocean and its marginal seas. By comparing the radiolarian species lists from the Norwegian Sea, Okhotsk Sea, Bering Sea and the North Pacific it is possible to conclude that in the Arctic Ocean 48 species are common with the Norwegian Sea fauna, 52 with fauna of Okhotsk Sea and 56 are also distributed in the North Pacific. It was established, that the most diverse fauna was obtained in the area of the Fram strait (42 species) and in the Chukchi Sea (40 species). Both regions are probably areas of expatriation of the Norwegian Sea and Pacific Ocean faunas, respectively, because radiolarian species (and specimens) were found only in low numbers elsewhere in the Arctic Ocean. The radiolarian fauna of the Arctic Ocean is a derivative of the Atlantic fauna. The radiolarian species composition in the Arctic Ocean indicates that radiolarian fauna elements also migrate from the Pacific Ocean. However, the most abundant and widely distributed species of the Pacific assemblages are not found in the Chukchi Sea. 26 radiolarian species have been found in the deposits of the central Arctic Ocean basins, but only 8 species have a circumpolar distribution. The number of nassellarian species are 2-5 times higher than the number of spumellarian species, but the abundance of spumellarian skeletons are many times (4-38) higher, than for the nassellarian skeletons. However, in the bottom sediments of the marginal seas the abundance of nassellarian skeletons exceeds many times the number of spumellarian skeletons. No endemic radiolarian species are present in the Arctic Ocean. The structure of the Arctic Ocean radiolarian associations are the same as in the closed and semiclosed epicontinental seas. Here there is a rather low species diversity and a high level of dominance of single species. Furthermore, the high rank taxa associations are characteristic for the different areas.

• Dolven, Jane Karine Lønne; Cortese, Giuseppe; Bjørklund, Kjell R & Malmgren, B.A. (2004). Late Pleistocene-Holocene radiolarian paleotemperatures in the Norwegian Sea based on artificial neural networks. Full text in Research Archive
• Cortese, Giuseppe; Bjørklund, Kjell R & Dolven, Jane Karine Lønne (2003). Species and assemblage distribution of Polycystine Radiolarians in recent sediments of the Nordic Seas. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe & Bjørklund, Kjell R (2003). Late Pleistocene-Holocene sea surface temperatures in the Norwegian Sea based on polycystine radiolarians. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe & Bjørklund, Kjell R (2003). Polycystine radiolarians as paleotemperature proxy during the Late Pleistocene-Holocene in the Norwegian Sea. Full text in Research Archive
• Bjørklund, Kjell R (2003). Professor vil samarbeida med sogningar og japanarar: Sognefjorden er perfekt for forsking. [Journal]. Sogn Avis. Full text in Research Archive
• Bjørklund, Kjell R & Kruglikova, Svetlana (2001). Polysystine radiolarier i dagens overflatesedimenter i Polhavet: Artssamfunn, alder ig innvandring. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe & Bjørklund, Kjell R (2001). Radiolarian paleotemperatures in the Norwegian Sea: the last 13.400 years. Full text in Research Archive
• Cortese, Giuseppe; Bjørklund, Kjell R & Dolven, Jane Karine Lønne (2001). Species and assemblage distribution of polycystine radiolarians in the Greenland-Iceland-Norwegian (GIN) Seas. Full text in Research Archive
• Kruglikova, Svetlana & Bjørklund, Kjell R (2001). The Arctic Basin: Radiolaria and Paleoceanology (engelsk sammendrag). Full text in Research Archive
• Ciecielski, P.F. & Bjørklund, Kjell R (2001). AGE AND DEPOSITIONAL ENVIRONMENT OF ZAIANGO CORE KZAI 10 (22 pp.). [Radio]. Gainesville. Full text in Research Archive
• Dolven, Jane Karine Lønne; Weber, Mysti; Bjørklund, Kjell R; Pisias, Nick & Cortese, Giuseppe (2001). A comparison of radiolarian species in the Nordic Seas (Greenland, Iceland and Norwegian Seas) and the North Pacific Ocean. Full text in Research Archive
• Dolven, Jane Karine Lønne & Bjørklund, Kjell R (2000). An early Holocene peak occurrence and Recent distribution of Rhizoplegma boreale (Cleve) in the Nordic Seas. Full text in Research Archive
• Kruglikova, Svetlana & Bjørklund, Kjell R (2000). Polycystine Radiolarians in the Arctic Basin Surface Sediments. Full text in Research Archive
• Dolven, Jane Karine Lønne; Weber, Mysti; Bjørklund, Kjell R & Pisias, Nick (2000). A comparison of radiolarian species in the Nordic Seas (Greenland, Iceland and Norwegian Seas) and the Pacific Ocean. Full text in Research Archive
• Ciesielski, P.F. & Bjørklund, Kjell R (1999). AGE AND DEPOSITIONAL ENVIRONMENT OF ZAIANGO CORE KZAI 2 (20 pp.). [Radio]. Gainesville. Full text in Research Archive
• Bjørklund, Kjell Rasmus & Kruglikova, S.B. (1998). Structure of radiolarian assemblages on high rank taxa and species level from the recent sediments of the Greenland-Iceland-Norwegian Basins and Norwegian fjords. Full text in Research Archive
• Dolven, Jane Karine Lønne; Cortese, Giuseppe & Bjørklund, Kjell R (1998). Surface Sediment Radiolarian Faunal Provinces and a Paleotemperature Reconstruction Across the Younger Dryas-Holocene Boundary in the Eastern Norwegian Sea. Full text in Research Archive
• Dolven, Jane Karine Lønne; Bjørklund, Kjell R & Cortese, Giuseppe (1997). Late Pleistocene-Middle Holocene radiolarian biostratigraphy, assemblages and paleotemperatures in the southeastern Norwegian Sea. Full text in Research Archive
• Kruglikova, Svetlana & Bjørklund, Kjell R (1995). The distribution of high rank Radiolarian taxa in recent sediments from the Norwegian Sea and Norwegian fjords: a quantitative and comparative evaluation. Full text in Research Archive

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