Effects of attached bacteria on organic aggregate settling velocity in seawater

Aquatic Microbial Ecology

Kazuhiro Kogure¹  Toshi Nagata¹  Katsuyuki Inoue¹  Yosuke Yamada¹  Hideki Fukuda¹ 

关键词: Bacteria;    Aggregate;    Settling velocity;    Porosity;    Marine environments;   

DOI  :  10.3354/ame01658

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: We investigated whether attached bacteria affect the settling velocity of organic aggregates via modifications of the physical properties of aggregates, including density, porosity, and morphology. Model aggregates, prepared by mixing 2 different polysaccharides (fucoidan and chitosan), were incubated in coastal seawater passed through either 0.8 µm (AGG_0.8) or 0.2 µm (AGG_0.2) filters. After incubation for 48 h, AGG_0.8 were much more densely (3.2- to 10.1-fold) colonized by bacteria than AGG_0.2. Based on median settling velocities (W₅₀), as determined by laser in situ scattering and transmissometry, the W₅₀ of AGG_0.8 was lower (1.6- to 4.5-fold) than that of AGG_0.2 for a size class of 62 to 119 µm. Stokes model analyses indicated that this reduction in W₅₀ could be largely attributed to the higher porosities of AGG_0.8 (0.932-0.981) than those of AGG_0.2 (0.719-0.929). Our results support the notion that the modification of aggregate structure by attached bacteria (porosity enhancement) can be an important factor controlling the settling velocity of marine particles.

【 授权许可】

Unknown