Effects of Modified Clay on Phaeocystis globosa Growth and Colony Formation

Abstract

Phaeocystis globosa is a globally distributed harmful algal blooms (HABs) species dominated by the colonial morphotype, which presents dramatic environmental hazards and poses a threat to human health. Modified clay (MC) can effectively flocculate HAB organisms and prevent their subsequent growth, but the effects of MC on colony-dominated P. globosa blooms remain uncertain. In this paper, a series of removal and incubation experiments were conducted to investigate the growth, colony formation and colony development of P. globosa cells after treatment with MC. The results show that the density of colonies was higher at MC concentrations below 0.2 g/L compared to those in the control, indicating the role of P. globosa colonies in resistance to environmental stress. Concentrations of MC greater than 0.2 g/L could reduce the density of solitary cells and colonies, and the colony diameter and extracellular polysaccharide (EPS) content were also decreased. The adsorption of MC to dissolved inorganic phosphorus (DIP) and the cell damage caused by collision may be the main mechanisms underlying this phenomenon. These results elucidate that the treatment with an appropriate concentration of MC may provide an effective mitigation strategy for P. globosa blooms by preventing their growth and colony formation.

Mechanism by Which MC Controls Harmful Algal Blooms Revealed by Cell Morphology of Aureococcus anophagefferens

“…In group 2, broken cells suffered a large area of membrane depression and rupture, while, in group 3, the broken cells burst, and the cytoplasmic contents flowed out through pores in the cell membrane. In both group 2 and group 3, nearly all the residual cell peripheries became clear, illustrating that NC and MC can decrease EPS, in accordance with the report by Ren et al [37]. It should be noted that A. anophagefferens does not have a cell wall, and the EPS sheath is an important barrier.…”

Investigation on the influence of crosslinking and swelling properties of modified silica-chitosan films for the controlled removal of Alexandrium minutum

“…80% within 3 min of exposure [21] Xanthane and calcium ydroxide modi ed clays, soils, and sands) Amphidinium carterae 83-89% within 30 min of exposure [22] Modi ed soil using amphoteric starch (AS) and poly-aluminium chloride (PAC)…”

“…The digital microscopic images showed that the algae cells attached to the CHT/SiO 2 /Gly ruptured (Fig 8(a)), whereas the algae cells on the CHT/SiO 2 /GPTEOS lm remained intact. Since NH 2 group of chitosan is preserved in CH/SiO 2 / Gly, the positively charged amine groups in the chitosan structure could induce stress to the algal cells and promotes cell rupturing [21,52]. Whereas in CHT/SiO 2 /GPTEOS lm, most of the NH 2 of chitosan is used up during the crosslinking process, hence further reducing the electrostatic charge and prevented the algae cells from rupturing.…”

“…The removal e ciency is attributed to the synergistic processes of charge neutralization and netting-bridging. Ren et al [21] reported that PAC modi ed kaolin successfully inhibited more than 90% of Phaeocystis globose. The group has concluded that the modi ed clay may have damaged the cell walls upon collision, in addition, to be able to change the environment to suppress the growth of Phaeocystis globose.…”