Work

Effects of attached bacteria on organic aggregate settling velocity in seawater

Year: 2013

Type: article

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 10.1fold) colonized by bacteria than AGG 0.2 .Based on median settling velocities (W 50 ), as determined by laser in situ scattering and transmissometry, the W 50 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 W 50 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.

Source: Aquatic Microbial Ecology

DOI: 10.3354/ame01658

Authors: Y Yamada, H Fukuda, K Inoue, K Kogure, T Nagata

Institutions: Atmosphere and Ocean Research Institute, The University of Tokyo, The University of Tokyo

Language: English

Topic: Marine Plankton and Biogeochemistry

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDGs: Life below water, Clean water and sanitation

Open Access status: bronze

Funders: Japan Society for the Promotion of Science, Core Research for Evolutional Science and Technology