Characteristics of Eukaryotic Plankton Communities in the Cold Water Masses and Nearshore Waters of the South Yellow Sea

Yanfeng Sun,Chao Wu,Congcong Guo,Yang Liu,Jun Sun,Liuyang Li,Xiaoting Fu

doi:10.3390/d13010021

Abstract

Eukaryotic plankton are important parts of the marine biome and play an important role in maintaining the stability of marine ecosystems. In order to characterize the eukaryotic plankton communities in the South Yellow Sea Cold Water Mass (CWM) and the South Yellow Sea nearshore waters (NW) in October 2019, Illumina high–throughput sequencing was performed using the 18S rDNA V9 region as the target gene. Environmental factors (depth, pH, salinity, temperature, Chl a, nitrate, nitrite, ammonium, silicate, phosphate) in two sea areas were measured, and their correlations with abundance and diversity of eukaryotic plankton were analyzed. A total of 807 species of plankton were identified, of which 663 species in 24 categories were from the CWM area, and 614 species in 26 categories were from NW. The total phytoplankton abundance in CWM waters was higher than that in NW. Dinophyta and Bacillariophyta were the most abundant phyla of phytoplankton in the two areas. Arthropoda and Cnidaria were the major zooplankton taxa. The dominant fungal population was mainly Basidiomycota. Both the CWM and NW have effects on dissolved inorganic nutrient concentrations and plankton abundance. Environmental factor correlation analysis showed that the concentration of dissolved inorganic nutrients within the CWM increased with water depth and the abundance of plankton gradually increased. Ammonium salts, nitrates, phosphates, silicates and water depth were important factors affecting phytoplankton growth. Phytoplankton abundance increased with increasing concentrations of inorganic nutrients. Bacillariophyta showed a strong positive correlation with silicates and depth. Depth and microscopic phytoplankton abundance were important factors influencing the structure of the zooplankton community.

Highlights

The ocean occupies 71% of Earth’s surface and plays a vital role in global ecology and socioeconomics [1,2]
These results indicate that there was no significant difference in eukaryotic plankton diversity between the Cold Water Mass (CWM) and nearshore waters (NW)
We used Illimina high-throughput sequencing technology to amplify the 18S rDNA V9 region DNA to explore the community structure of plankton in the South Yellow Sea, and we found that the number of reads in CWM waters was as high as 1,160,460 with 4006 operational taxonomic units (OTUs); the number of reads in NW was 904,775 with 2591 OTUs

Summary

Introduction

The ocean occupies 71% of Earth’s surface and plays a vital role in global ecology and socioeconomics [1,2]. As an important component of marine systems, changes in plankton populations and community structure have a direct impact on ecosystem function [3,4] and are sensitive indicators of environmental changes such as nutrient inputs, global climate change and the impacts of human activities [5]. Zooplankton are key links between primary productivity and higher trophic levels in the marine food web and a part of a “biological pump” that transfers carbon immobilized by phytoplankton deeper into the ocean, and they play an important role in environmental pollution monitoring [13]. The study of eukaryotic plankton diversity and community structure plays an important role in revealing the ecosystem functions of corresponding waters

Methods

Findings

Discussion

Conclusion