Dataset Information

Vertical fluxes of nutrients enhanced by strong turbulence and phytoplankton bloom around the ocean ridge in the Luzon Strait.

ABSTRACT: Steep oceanic ridges and tidal currents in the Luzon Strait generate some of the world's strongest turbulent mixing. To evaluate the impacts of the turbulence intensity on the marine ecosystem, we carried out measurements of microstructure turbulence and biogeochemical hydrography along 21°N in the Luzon Strait during the R/V Hakuho Maru cruise, KH-17-5-2, in November 2017. We found a turbulent kinetic energy dissipation rate exceeding O(10^-7) W kg^-1 and vertical eddy diffusivity exceeding O(10^-3) m² s^-1, two orders of magnitude larger than those in the open ocean, above a shallow sub-ridge on the eastern ridge of the Luzon Strait. In addition, a clear chlorophyll a bloom was identified in the surface layer above the sub-ridge from in situ measurements and satellite observations. High values of nitrate (4.7 mmol N m^-2 d^-1) and phosphate (0.33 mmol P m^-2 d^-1) fluxes estimated near the base of the surface chlorophyll a bloom strongly suggest that enhanced turbulent mixing promotes nutrient supply to the euphotic zone and generates new production within the surface layer, contributing to the formation of a quasi-permanent local chlorophyll a bloom north of Itbayat Island on the eastern ridge.

SUBMITTER: Tsutsumi E

PROVIDER: S-EPMC7577972 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Vertical fluxes of nutrients enhanced by strong turbulence and phytoplankton bloom around the ocean ridge in the Luzon Strait.

Tsutsumi Eisuke E Matsuno Takeshi T Itoh Sachihiko S Zhang Jing J Senjyu Tomoharu T Sakai Akie A Lee Keunjong K Yanagimoto Daigo D Yasuda Ichiro I Ogawa Hiroshi H Villanoy Cesar C

Scientific reports 20201021 1

Steep oceanic ridges and tidal currents in the Luzon Strait generate some of the world's strongest turbulent mixing. To evaluate the impacts of the turbulence intensity on the marine ecosystem, we carried out measurements of microstructure turbulence and biogeochemical hydrography along 21°N in the Luzon Strait during the R/V Hakuho Maru cruise, KH-17-5-2, in November 2017. We found a turbulent kinetic energy dissipation rate exceeding O(10<sup>-7</sup>) W kg<sup>-1</sup> and vertical eddy diffu ...[more]

PMID: 33087854

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Project description:Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6-65%) as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12-86%) dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in three independent bloom events. Other environmental variables such as nitrate and phosphate and temperature appear to influence some low abundant bacterial groups as well. Our results suggest that phytoplankton-associated bacterial communities are strongly affected not just by phytoplankton bloom in general, but also by the type of algal species that dominates in the natural bloom.

Dataset Information

Vertical fluxes of nutrients enhanced by strong turbulence and phytoplankton bloom around the ocean ridge in the Luzon Strait.

Publications

Vertical fluxes of nutrients enhanced by strong turbulence and phytoplankton bloom around the ocean ridge in the Luzon Strait.

Similar Datasets

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