Oxygen gradients shape the unique structure of picoeukaryotic communities in the Bay of Bengal

Zhuo Chen; Ting Gu; Xingzhou Wang; Xi Wu; Jun Sun

doi:10.1016/j.scitotenv.2021.152862

Oxygen gradients shape the unique structure of picoeukaryotic communities in the Bay of Bengal

Sci Total Environ. 2022 Mar 25:814:152862. doi: 10.1016/j.scitotenv.2021.152862. Epub 2022 Jan 8.

Authors

Zhuo Chen¹, Ting Gu², Xingzhou Wang², Xi Wu³, Jun Sun⁴

Affiliations

¹ College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China,; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.
² Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.
³ College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan, China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.
⁴ College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan, China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan, Hubei 430074, PR China. Electronic address: phytoplankton@163.com.

PMID: 35016938
DOI: 10.1016/j.scitotenv.2021.152862

Abstract

Picoeukaryotic communities respond rapidly to global climate change and play an important role in marine biological food webs and ecosystems. The formation of oxygen minimum zones (OMZ) is facilitated by the stratification of seawater and higher primary production in the surface layer, and the marine picoeukaryotic community this low-oxygen environment is topic of interest. To better understand the picoeukaryotic community assembly mechanisms in an OMZ, we collected samples from the Bay of Bengal (BOB) in October and November 2020 and used 18S rDNA to study the picoeukaryotic communities and their community assembly mechanisms that they are controlled by in deep-sea and hypoxic zones. The results show that deterministic and stochastic processes combine to shape picoeukaryotic communities in the BOB. We divided the water column into three vertical layers: the upper oxycline (UO), the OMZ, and the lower oxycline (LO), based on dissolved oxygen concentrations (dissolved oxygen: UO > LO > OMZ) at vertical depths (from 5 m to 2000 m). Deterministic processes controlled the picoeukaryotic community in the UO, while the picoeukaryotic communities in the OMZ and LO were dominated by stochastic processes. The OMZ had a stronger diffusional limitation and the habitat niche breadth in the UO was wider than that in OMZ and LO. We classified the picoeukaryotic community into three functional composition types (phototrophic, mixotrophic, and heterotrophic); heterotrophs were most abundant in the surveyed area, and the proportion of decreased significantly with increasing depth and decreasing dissolved oxygen. The picoeukaryotes in the investigated area also correlated with temperature, salinity, and nutrients (phosphate, silicate, nitrate, nitrite, and ammonium). These findings contribute to a better understanding of picoeukaryotic communities in deep-sea and low-oxygen environments, their functional structuring, as well as the effects of environmental changes on their community structure.

Keywords: Assembly mechanisms; Bay of Bengal; Functional composition; Oxygen minimum zone; Picoeukaryote.

MeSH terms

Bacteria
Bays
Ecosystem*
Oxygen* / analysis
Seawater

Substances

Oxygen