Biodiversity and Spatial-Temporal Dynamics of Margalefidinium Species in Jiaozhou Bay, China.

Shuya Liu,Nansheng Chen,Yongfang Zhao,Mengjia Zhang

doi:10.3390/ijerph182111637

Abstract

Many Margalefidinium species are cosmopolitan harmful algal bloom (HAB) species that have caused huge economic and ecological damage. Despite extensive research on Margalefidinium species, the biodiversity and spatial-temporal dynamics of these species remain obscure. Jiaozhou Bay is an ideal area for HAB research, being one of the earliest marine survey areas in China. In this study, we carried out the first metabarcoding study on the temporal and spatial dynamics of Margalefidinium species using the 18S rDNA V4 region as the molecular marker and samples collected monthly at 12 sampling sites in Jiaozhou Bay in 2019. Two harmful Margalefidinium species (M. polykrikoides and M. fulvescens) were identified with potentially high genetic diversity (although we cannot rule out the possibility of intra-genome sequence variations). Both M. polykrikoides and M. fulvescens demonstrated strong temporal preference with a sharp peak of abundance in early autumn (September), but without showing strong location preference in Jiaozhou Bay. Our results revealed that temperature might be the main driver for their temporal dynamics. Knowledge of biodiversity and spatial-temporal dynamics of the Margalefidinium species may shed light on the understanding of mechanisms underlying strongly biased occurrences of Margalefidinium blooms recorded globally.

Highlights

The genus Margalefidinium, which contains five species, namely, M. polykrikoides, M. fulvescens, M. catenatum, M. citron, and M. flavum, was recently transferred from the genus Cochlodinium on the basis of morphological and phylogenetic analyses [1]
A total of 45,932 ASVs were obtained from the seawater samples collected from the 12 sampling sites in Jiaozhou Bay (Figure 1) in 12 months in 2019, 30,097 ASVs of which were supported by at least two reads [33]
Of these 30,097 ASVs, 28 ASVs were annotated as Margalefidinium species, including 1 ASV corresponding to M. polykrikoides, 18 ASVs corresponding to M. fulvescens, and 9 ASVs annotated to an unknown species of the genus Margalefidinium (Table 1)

Summary

Introduction

The genus Margalefidinium, which contains five species, namely, M. polykrikoides, M. fulvescens, M. catenatum, M. citron, and M. flavum, was recently transferred from the genus Cochlodinium on the basis of morphological and phylogenetic analyses [1]. It belongs to the family Gymnodiniaceae, order Gymnodiniales, class Dinophyceae, and phylum. Each of the five species has an eyespot in the episome that may be important for photoreception Both of them are large (>40 μm) and unarmored, commonly form chains, and have shallow sulcus without harboring longitudinal flagellum [4,5]. They differ in chloroplast shape, eyespot, and the position of sulcus, which are discernible under light microscopy, and in morphology

Methods

Results

Discussion

Conclusion