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20 pages, 7627 KiB

Open AccessArticle

Seasonal Patterns of Picocyanobacterial Community Structure in the Kuroshio Current

by Ya-Fan Chan, Chih-Ching Chung, Gwo-Ching Gong, I-Jung Lin and Ching-Wei Hsu

Biology 2023, 12(11), 1424; https://doi.org/10.3390/biology12111424 - 13 Nov 2023

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The nutrient-scarce, warm, and high-salinity Kuroshio current has a profound impact on both the marine ecology of the northwestern Pacific Ocean and the global climate. This study aims to reveal the seasonal dynamics of picoplankton in the subtropical Kuroshio current. Our results showed [...] Read more.

The nutrient-scarce, warm, and high-salinity Kuroshio current has a profound impact on both the marine ecology of the northwestern Pacific Ocean and the global climate. This study aims to reveal the seasonal dynamics of picoplankton in the subtropical Kuroshio current. Our results showed that one of the picocyanobacteria, Synechococcus, mainly distributed in the surface water layer regardless of seasonal changes, and the cell abundance ranged from 10⁴ to 10⁵ cells mL⁻¹. In contrast, the maximum concentration of the other picocyanobacteria, Prochlorococcus, was maintained at more than 10⁵ cells mL⁻¹ throughout the year. In the summer and the autumn, Prochlorococcus were mainly concentrated at the water layer near the bottom of the euphotic zone. They were evenly distributed in the euphotic zone in the spring and winter. The stirring effect caused by the monsoon determined their distribution in the water column. In addition, the results of 16S rRNA gene diversity analysis showed that the seasonal changes in the relative abundance of Synechococcus and Prochlorococcus in the surface water of each station accounted for 20 to 40% of the total reads. The clade II of Synechococcus and the High-light II of Prochlorococcus were the dominant strains in the waters all year round. Regarding other picoplankton, Proteobacteria and Actinobacteria occupied 45% and 10% of the total picoplankton in the four seasons. These data should be helpful for elucidating the impacts of global climate changes on marine ecology and biogeochemical cycles in the Western Boundary Currents in the future. Full article

(This article belongs to the Special Issue Climate Change and Marine Plankton)

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18 pages, 10094 KiB

Open AccessArticle

Biogeographic Analysis Suggests Two Types of Planktonic Prokaryote Communities in the Barents Sea

by Zorigto Namsaraev, Aleksandra Kozlova, Fedor Tuzov, Anastasia Krylova, Anna Izotova, Ivan Makarov, Andrei Bezgreshnov, Anna Melnikova, Anna Trofimova, Denis Kuzmin, Maksim Patrushev and Stepan Toshchakov

Biology 2023, 12(10), 1310; https://doi.org/10.3390/biology12101310 - 05 Oct 2023

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Abstract

The Barents Sea is one of the most rapidly changing Arctic regions, with an unprecedented sea ice decline and increase in water temperature and salinity. We have studied the diversity of prokaryotic communities using 16S metabarcoding in the western and northeastern parts of [...] Read more.

The Barents Sea is one of the most rapidly changing Arctic regions, with an unprecedented sea ice decline and increase in water temperature and salinity. We have studied the diversity of prokaryotic communities using 16S metabarcoding in the western and northeastern parts of the Barents Sea along the Kola Section and the section from Novaya Zemlya to Franz Joseph Land. The hypothesis-independent clustering method revealed the existence of two distinct types of communities. The most common prokaryotic taxa were shared between two types of communities, but their relative abundance was different. It was found that the geographic location of the sampling sites explained more than 30% of the difference between communities, while no statistically significant correlation between environmental parameters and community composition was found. The representatives of the Psychrobacter, Sulfitobacter and Polaribacter genera were dominant in samples from both types of communities. The first type of community was also dominated by members of Halomonas, Pseudoalteromonas, Planococcaceae and an unclassified representative of the Alteromonadaceae family. The second type of community also had a significant proportion of Nitrincolaceae, SAR92, SAR11 Clade I, NS9, Cryomorphaceae and SUP05 representatives. The origin of these communities can be explained by the influence of environmental factors or by the different origins of water masses. This research highlights the importance of studying biogeographic patterns in the Barents Sea in comparison with those in the North Atlantic and Arctic Ocean prokaryote communities. Full article

(This article belongs to the Special Issue Climate Change and Marine Plankton)

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20 pages, 2815 KiB

Open AccessArticle

Contrasting Marine Microbial Communities of the Fram Strait with the First Confirmed Record of Cyanobacteria Prochlorococcus marinus in the Arctic Region

by Monika Mioduchowska, Joanna Pawłowska, Karol Mazanowski and Agata Weydmann-Zwolicka

Biology 2023, 12(9), 1246; https://doi.org/10.3390/biology12091246 - 17 Sep 2023

Cited by 1 | Viewed by 1334

Abstract

The seawater microbiome is crucial in marine ecosystems because of its role in food chains and biogeochemical cycles; thus, we studied the composition of the pelagic marine microbiome collected in the upper 50 m on the opposite sides of Fram Strait: Spitsbergen and [...] Read more.

The seawater microbiome is crucial in marine ecosystems because of its role in food chains and biogeochemical cycles; thus, we studied the composition of the pelagic marine microbiome collected in the upper 50 m on the opposite sides of Fram Strait: Spitsbergen and Greenland shelves. We found out that it differed significantly, with salinity being the main environmental variable responsible for these differences. The Spitsbergen shelf was dominated by Atlantic Waters, with a rather homogenous water column in terms of salinity and temperature down to 300 m; hence, the marine microbial community was also homogenous at all sampled depths (0, 25, 50 m). On the contrary, stations on the Greenland shelf were exposed to different water masses of both Arctic and Atlantic origin, which resulted in a more diverse microbial community there. Unexpectedly, for the very first time, we identified cyanobacterium Prochlorococcus marinus in Arctic waters (Spitsbergen shelf, 75–77° N). Till now, the distribution of this cyanobacteria in oceans has been described only between 40° N and 40° S. Considering the accelerated rate of climate warming in the Arctic, our results indicated that the seawater microbiome can be viewed as an amplifier of global change and that the Atlantification is in progress. Full article

(This article belongs to the Special Issue Climate Change and Marine Plankton)

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