Review
Oceanography
Dong Yan, Jun Nishioka, Takenobu Toyota, Koji Suzuki
Summary: The Sea of Okhotsk plays a key role in the seawater circulation of the North Pacific Ocean. During winter, sea ice forms in the northern shelf and is transported to the southern part of the sea by the East Sakhalin Current. Diatoms are the dominant microalgae in the sea ice ecosystem, with Thalassiosira spp., Porosira glacialis, and Fragilariopsis cylindrus being the major species. The presence of the East Sakhalin Current influences the composition and abundance of microalgae in the seawater stations, with higher concentrations of dissolved Fe and ammonia. The study suggests that the winter phytoplanktonic communities in the southern Sea of Okhotsk are largely dependent on the presence of the East Sakhalin Current.
PROGRESS IN OCEANOGRAPHY
(2022)
Article
Geosciences, Multidisciplinary
S. Kishi, K. I. Ohshima, J. Nishioka, N. Isshiki, S. Nihashi, S. C. Riser
Summary: The data collected by profiling floats deployed in the Sea of Okhotsk indicate that sea-ice melt may be a significant factor in promoting phytoplankton blooms, especially in the southwestern region where iron availability is limited. Sea-ice melt likely induces prominent phytoplankton blooms by providing iron supply.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Haakon Hop, Anette Wold, Amelie Meyer, Allison Bailey, Maja Hatlebakk, Slawomir Kwasniewski, Peter Leopold, Piotr Kuklinski, Janne E. Soreide
Summary: The impact of the rapidly changing Arctic on zooplankton community structure and seasonal behavior is not yet understood. Zooplankton in the Arctic region is more dependent on surrounding water mass characteristics, such as salinity and depth, rather than geographical location. Seasonal changes in the community are closely linked to algal food availability and seasonal changes from winter to spring.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Environmental Sciences
Edson Silva, Francois Counillon, Julien Brajard, Anton Korosov, Lasse H. Pettersson, Annette Samuelsen, Noel Keenlyside
Summary: Phytoplankton blooms play a crucial role in marine ecosystems by providing biomass, aiding carbon sequestration, and potentially posing risks when harmful species are involved. The seasonal blooms in the Barents, Norwegian, and North seas are influenced by factors such as mixed layer depth, sea surface temperature, wind speed, and suspended particulate matter. Variability in the timing and intensity of spring and summer blooms in these regions can be attributed to unique environmental conditions and oceanographic processes.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Oceanography
Mizuki Kuga, Kay Ohshima, Noriaki Kimura, Kazuki Nakata, Yasushi Fukamachi
Summary: In the southwestern Sea of Okhotsk, a large spring phytoplankton bloom occurs after the sea ice melts. It is believed that the sea ice, containing materials such as iron-containing sediment or ice algae, is transported from the north and melted, leading to a prominent bloom. This study suggests that the sea ice that enhances the spring bloom originates from active coastal polynyas in the upstream region. Using a particle-tracking method, the researchers simulated the transport of sea ice produced in the coastal polynyas and identified Terpenia Bay and Sakhalin polynyas as the main sources of sea ice in the western Kuril Basin. The study also highlights the importance of melt ice from the Terpenia Bay polynya in the frazil ice production.
JOURNAL OF OCEANOGRAPHY
(2022)
Article
Oceanography
Victoria Hill, Bonnie Light, Michael Steele, Andrew Lowy Sybrandy
Summary: Novel observations were collected on the seasonal evolution of an ice algal bloom on the Chukchi shelf using two autonomous buoys. The differences in ice algae biomass under each buoy were driven by variations in snow thickness, with nutrients being limiting at the low snow site and light being limiting at the high snow site.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Chemistry, Medicinal
Julie Seveno, Ana Car, Damien Sirjacobs, Lovina Fullgrabe, Iris Dupcic Radic, Pierre Lejeune, Vincent Leignel, Jean-Luc Mouget
Summary: Blue Haslea species are able to synthesize blue pigments with beneficial properties. This study describes the benthic blooms of blue Haslea species in open environments, and highlights the importance of light and water temperature in their dynamics.
Article
Multidisciplinary Sciences
Linda Armbrecht, Michael E. Weber, Maureen E. Raymo, Victoria L. Peck, Trevor Williams, Jonathan Warnock, Yuji Kato, Ivan Hernandez-Almeida, Frida Hoem, Brendan Reilly, Sidney Hemming, Ian Bailey, Yasmina M. Martos, Marcus Gutjahr, Vincent Percuoco, Claire Allen, Stefanie Brachfeld, Fabricio G. Cardillo, Zhiheng Du, Gerson Fauth, Chris Fogwill, Marga Garcia, Anna Glueder, Michelle Guitard, Ji-Hwan Hwang, Mutsumi Iizuka, Bridget Kenlee, Suzanne O'Connell, Lara F. Perez, Thomas A. Ronge, Osamu Seki, Lisa Tauxe, Shubham Tripathi, Xufeng Zheng
Summary: Antarctica is susceptible to climate change, and it is crucial to study the responses of the polar marine ecosystem to ensure urgent action. Sedimentary ancient DNA analysis provides insights into ecosystem-wide changes, as demonstrated in this study of the Scotia Sea region.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
C. W. Lester, T. J. W. Wagner, Dylan E. McNamara, M. R. Cape
Summary: The study suggests that the spring blooms of phytoplankton in the Arctic Ocean are highly dependent on sea-ice meltwater for horizontal mixing and maintaining the stratified upper ocean. When meltwater concentration is sufficient, it allows phytoplankton to be confined near the surface, exposed to enough sunlight for optimal growth. The findings support the central role of sea-ice meltwater in shaping the spatial patterns of Arctic phytoplankton blooms.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Kazuhiro Yoshida, Andreas Seger, Matthew Corkill, Petra Heil, Kristen Karsh, Andrew McMinn, Koji Suzuki
Summary: Sea-ice algae play a crucial role in sea-ice ecosystems, but under low iron conditions, their photosynthetic flexibility is affected, potentially leading to detrimental consequences for ice algal production and trophic interactions.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Meteorology & Atmospheric Sciences
Matthew Z. Williams, Melissa Gervais, Chris E. Forest
Summary: This study provides a comprehensive view of the processes contributing to interannual variability in sea ice coverage in the Sea of Okhotsk, showing that thermodynamic processes involving anomalous ocean-atmosphere heat fluxes and low-level wind anomalies in winter play key roles. The study also confirms the Rossby wave train response triggered by anomalous ocean-atmosphere heat fluxes, validating previous findings in a more realistic coupled model framework.
Article
Oceanography
Mizuki Kuga, Kay I. Ohshima, Sachiko Kishi, Noriaki Kimura, Takenobu Toyota, Jun Nishioka
Summary: Material transport by sea ice is crucial for the biological production of spring blooms. The origin of sea ice is related to biological production, iron concentration, and frazil ice fraction. Coastline areas, specifically Terpenia Bay and Sakhalin polynyas, are found to be the main sources of sea ice, where incorporation of sedimentary particles contributes to high biological production. Furthermore, sea ice samples collected from the Hokkaido coast suggest that shallow shelf areas around the southern tip of Sakhalin Island are the formation sites, while samples with high iron concentration from deeper shelf slope areas are likely transported from the northern region to Terpenia Bay.
JOURNAL OF OCEANOGRAPHY
(2023)
Article
Limnology
Clara J. M. Hoppe
Summary: The end of polar night marks the start of photosynthetic biomass production in the Arctic marine ecosystem, with the spring bloom being the most crucial event. This dataset reveals significant in situ biomass accumulation during the dark-light transition in the high Arctic for the first time, as well as the earliest positive net primary production rates recorded.
LIMNOLOGY AND OCEANOGRAPHY LETTERS
(2022)
Article
Oceanography
Takenobu Toyota, Noriaki Kimura, Jun Nishioka, Masato Ito, Daiki Nomura, Humio Mitsudera
Summary: The sea ice in the southern Sea of Okhotsk has significant impacts on freshwater input and primary production, but its interannual variability is not well understood yet. Long-term field observations and satellite data analysis revealed that the sea ice in this region is uncorrelated with that in the northern and central regions, and its thickness and volume are mainly controlled by dynamical pile-up processes, rather than the thermodynamical freezing conditions.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Environmental Sciences
Yuri Fukai, Kohei Matsuno, Amane Fujiwara, Koji Suzuki
Summary: Diatoms in the Pacific Arctic region form dense blooms and have high photophysiological plasticity and survival strategies in unfavorable conditions. They can quickly proliferate when sufficient light becomes available and have a high seeding potential in surface sediments, which is important for blooms in the Pacific Arctic shelf region.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Multidisciplinary Sciences
Youhei Yamashita, Motohiro Nakane, Yutaro Mori, Jun Nishioka, Hiroshi Ogawa
Summary: The study reveals the distribution of dissolved black carbon in the Pacific Ocean, indicating a negative correlation between its concentration and deep-ocean circulation. The removal process of black carbon to abyssal sediments is estimated to account for a small percentage of anthropogenic CO2 uptake by the ocean.
NATURE COMMUNICATIONS
(2022)
Article
Oceanography
Kuo Hong Wong, Jun Nishioka, Taejin Kim, Hajime Obata
Summary: In this study, comprehensive distributions of dissolved manganese (dMn) in the subarctic Pacific were presented and compared with the data of dissolved iron (dFe) in the same region. The study revealed different vertical profiles for dMn and dFe and observed different forms in the size fractionation of these two micronutrients. The transport distances of dMn found in this study were the highest in the Pacific region, and this long-range transport could potentially impact phytoplankton growth through upwelling processes.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Oceanography
Ryosuke Futsuki, Toru Hirawake, Amane Fujiwara, Hisatomo Waga, Takashi Kikuchi, Shigeto Nishino, Tomonori Isada, Koji Suzuki, Yutaka W. Watanabe
Summary: This study evaluated the optical and productivity data in the Arctic Ocean during summer and autumn and investigated the performance and sensitivity of absorption-based algorithms. The results showed that the methods had little bias for in situ input parameters and reflectance, but there were problems with estimating quantum yield from only optical parameters.
JOURNAL OF OCEANOGRAPHY
(2022)
Article
Microbiology
Takako Masuda, Keisuke Inomura, Taketoshi Kodama, Takuhei Shiozaki, Satoshi Kitajima, Gabrielle Armin, Takato Matsui, Koji Suzuki, Shigenobu Takeda, Amitsuhide Sato, Ondrej Prasil, Ken Furuyaa
Summary: Crocosphaera watsonii is an important nitrogen-fixing microorganism in the ocean, capable of competing for and consuming combined nitrogen sources, and has high growth rates and adaptability.
MICROBIOLOGY SPECTRUM
(2022)
Article
Limnology
Shunyan Cheung, Kailin Liu, Kendra A. Turk-Kubo, Jun Nishioka, Koji Suzuki, Michael R. Landry, Jonathan P. Zehr, Szeki Leung, Lixia Deng, Hongbin Liu
Summary: Recent studies have found active nitrogen fixation in high-latitude waters, but the ecological controls on nitrogen-fixing organisms in such systems are still unclear. This study detected abundant UCYN-A, a nitrogen-fixing cyanobacteria, in the Gulf of Anadyr and identified a correlation between its abundance and the ratio of dissolved iron to dissolved inorganic nitrogen. The study also found selective grazing of UCYN-A in nitrogen-depleted waters and highlighted the importance of the Fe : DIN ratio in determining the abundance of UCYN-A in high-latitude waters.
LIMNOLOGY AND OCEANOGRAPHY LETTERS
(2022)
Article
Biochemistry & Molecular Biology
Hisashi Endo, Yu Umezawa, Shigenobu Takeda, Koji Suzuki
Summary: Haptophytes are a successful group of phytoplankton in the ocean, but little is known about the mechanisms behind their ecological success. In this study, observations were conducted across the Kuroshio Current to understand the community characteristics and interactions among haptophytes. It was found that the haptophyte community structure changed significantly in the East China Sea due to the influence of shelf waters with high phytoplankton biomass. Analysis suggested that haptophytes can coexist with their close relatives, possibly due to their nutritional flexibility. Noncalcifying haptophytes were identified as playing crucial roles in community diversity and stability, as well as the food web structure in the Kuroshio ecosystems.
Article
Limnology
Kailin Liu, Jun Nishioka, Bingzhang Chen, Koji Suzuki, Shunyan Cheung, Yanhong Lu, Huijun Wu, Hongbin Liu
Summary: This study investigates phytoplankton growth and microzooplankton grazing, two critical processes in marine food webs, in the subarctic western Pacific and the Bering Sea. Results show that phytoplankton growth is primarily determined by nutrient availability and temperature. In the high-nutrient, low-chlorophyll regions, iron availability is the limiting factor. In the Gulf of Anadyr and Kamchatka Strait, phytoplankton growth is mainly limited by inorganic nitrogen. Microzooplankton grazing rate is influenced by temperature and prey availability. The study reveals different food web structures in areas with and without riverine iron input.
LIMNOLOGY AND OCEANOGRAPHY
(2023)
Article
Ecology
Kazuhiro Yoshida, Hiroshi Ota, Takuya Iwanaga, Aiko Yoshitake, Takayuki Mine, Mana Omura, Kei Kimura
Summary: This study developed a novel species-specific quantitative PCR method to track the annual dynamics of seven Skeletonema species in the coastal waters of Ariake Sound, Japan. The results revealed different seasonality and occurrence patterns of these species, with three species forming blooms in summer and others increasing in winter. The study also highlighted the diverse ecophysiology within this cosmopolitan diatom genus.
MARINE ECOLOGY PROGRESS SERIES
(2023)
Article
Oceanography
Kazuhiro Yoshida, Jun Nishioka, Ichiro Yasuda, Koji Suzuki
Summary: In the western subarctic Pacific, iron can enhance the biological carbon pump by stimulating phytoplankton photosynthesis. However, little is known about how iron and light availability controls the phytoplankton photophysiology near the Kuril Islands. This study conducted experiments and found that iron and light co-limitation played a role in controlling phytoplankton growth in the water column, while in a shallower mixed layer station, iron was sufficient for phytoplankton growth.
JOURNAL OF OCEANOGRAPHY
(2023)
Article
Green & Sustainable Science & Technology
Aminur Rahman, Kazuhiro Yoshida, Mohammed Monirul Islam, Genta Kobayashi
Summary: In this study, orange peel cellulose (OPC) beads were used as adsorbents for the removal of heavy metals from wastewater. The adsorbent surface was analyzed using FT-IR and SEM-EDS. The concentrations of metals before and after adsorption were measured using ICP-MS. The maximum removal efficiency of metal ions occurred at pHs 4-8, and the Langmuir and Freundlich isotherm models confirmed the statistical significance of the adsorption processes.
Article
Environmental Sciences
Youhei Yamashita, Jun Nishioka
Summary: Through circulation of intermediate water, the marginal seas have been identified as important external sources of dissolved iron (Fe) in the North Pacific. This study presents comprehensive spatial distributions of dissolved Fe concentrations and Fe(III) solubilities over the North Pacific, including the marginal seas, the Sea of Okhotsk, and the Bering Sea. The results suggest that the major dissolved Fe chemical form derived from shelf and slope sediments in the marginal seas changed from colloidal Fe to FDOMH-Fe complexes.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Microbiology
Takako Masuda, Keisuke Inomura, Jan Mares, Taketoshi Kodama, Takuhei Shiozaki, Takato Matsui, Koji Suzuki, Shigenobu Takeda, Curtis Deutsch, Ondrej Prasil, Ken Furuya
Summary: This study addresses the question of how different plankton using the same essential nutrients coexist. The coexistence of Prochlorococcus and Synechococcus in low-nutrient waters can be sustained by specialization in the uptake of distinct nitrogen substrates. The findings suggest that climate change may shift the relative abundance of these dominant plankton genera in the ocean.
MICROBIOLOGY SPECTRUM
(2023)
Article
Biotechnology & Applied Microbiology
Ryo Orita, Kazuhiro Yoshida, Hiroto Terazono, Yukio Nagano, Masatoshi Goto, Kei Kimura, Genta Kobayashi
Summary: Environmental factors play a significant role in shaping estuarine microbial assemblages in both the water column and sediment surface. These two zones exhibit distinct compositions and are influenced by different environmental factors.
MICROBES AND ENVIRONMENTS
(2022)