The molecular mechanisms and environmental effects of modified clay control algal blooms in aquacultural water

Jianan Zhu; Zhiming Yu; Liyan He; Yuxin Jiang; Xihua Cao; Xiuxian Song

doi:10.1016/j.jenvman.2023.117715

The molecular mechanisms and environmental effects of modified clay control algal blooms in aquacultural water

J Environ Manage. 2023 Jul 1:337:117715. doi: 10.1016/j.jenvman.2023.117715. Epub 2023 Mar 17.

Authors

Jianan Zhu¹, Zhiming Yu², Liyan He¹, Yuxin Jiang³, Xihua Cao¹, Xiuxian Song⁴

Affiliations

¹ CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
² CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: zyu@qdio.ac.cn.
³ CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China.
⁴ CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China.

PMID: 36934499
DOI: 10.1016/j.jenvman.2023.117715

Abstract

Modified clay (MC) technology is an effective method for controlling harmful algal blooms (HABs). Based on field experience, a bloom does not continue after treatment with MC, even though the residual HAB biomass accounts for 20-30% of the initial biomass. Laboratory studies using unialgal cultures have found that MC could inhibit the growth of the residual algal cells to prevent HABs. Nevertheless, the phytoplankton in field waters is diverse. Therefore, unclassified complex mechanisms may exist. To illustrate the molecular mechanisms through which MC controls HABs in the field and verify the previous laboratory findings, a series of experiments and bioinformatics analyses were conducted using bloom waters from aquacultural ponds. The results showed that a 72.29% removal efficiency of algal biomass could effectively control blooms. The metatranscriptomic results revealed that the number of downregulated genes (131,546) was greater than that of upregulated genes (24,318) at 3 h after MC addition. Among these genes, several genes related to DNA replication were downregulated; however, genes involved in DNA repair were upregulated. Metabolism-related pathways were the most significantly upregulated (q < 0.05), including photosynthesis and oxidative phosphorylation. The results also showed that MC reduced most of the biomass of the dominant phytoplankton species, likely by removing apical dominance, which increased the diversity and stability of the phytoplankton community. In addition to reducing the pathogenic bacterial density, MC reduced the concentrations of PO₄^3- (96.22%) and SiO₃^2- (66.77%), thus improving the aquaculture water quality, altering the phytoplankton community structure (the proportion of Diatomea decreased, and that of Chlorophyta increased), and inhibiting phytoplankton growth. These effects hindered the rapid development of large phytoplankton biomasses and allowed the community structure to remain stable, reducing HAB threats. This study illustrates the molecular mechanisms through which MC controls HABs in the field and provides a scientific method for removing HABs in aquacultural waters.

Keywords: Aquacultural water; Bioinformatics analyses; Harmful algal blooms; Modified clay; Phytoplankton community structure.

MeSH terms

Aquaculture
Clay
Harmful Algal Bloom*
Phytoplankton* / genetics
Phytoplankton* / metabolism
Water Quality

Substances

Clay