TY - JOUR
T1 - Micro food web networks on suspended sediment
AU - Nguyen, Thu Ha
AU - Tang, Fiona H.M.
AU - Maggi, Federico
N1 - Funding Information:
This project was partly funded by the Civil Engineering Research and Development Scheme 2015 ( CERDS ) of The University of Sydney. T. H. N was supported by the Australia Awards Scholarship. F. M. was supported by the Sydney Research Accelerator (SOAR) Fellowship, the University of Sydney. The authors thank the Editor and the anonymous Reviewer for their constructive comments to the original manuscripts.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/12/1
Y1 - 2018/12/1
N2 - The genesis of suspended aggregates in aquatic ecosystems is not only a result of hydrodynamic mineral interactions but also a complex microbial food web network. A microbiological-physical model (BFLOC2) is introduced here to predict aggregate geometry and settling velocity under simultaneous effects of hydrodynamic and biological processes. While minerals can contribute to aggregate dynamics through collision, aggregation, and breakup, living microorganisms can colonize and establish food web interactions that involve growth and grazing, and modify the aggregate structure. The BFLOC2 model describes the aggregate dynamics resulting from interactions between minerals and three types of microorganisms, namely bacteria, flagellates, and ciliates. BFLOC2 was first calibrated against the size and capacity (fractal) dimension of aggregates formed in a pure mineral system at different mineral concentrations and fluid shear rates, and then against the abundance of aggregate-attached cells in a pure microbial environment. BFLOC2 model and calibrated parameters were then tested against biomineral aggregate size, capacity dimension, and biomass fraction formed in biomineral flocculation experiments at four nutrient concentrations. Modelling of biomineral aggregate dynamics over a wide range of environmental conditions showed that maximum aggregate size, biomass fraction, and settling velocity could occur at different optimal environmental conditions. Unlike mineral aggregates, which have maximum size when shear rate tends to zero, a relative maximum size of biomineral aggregates can be reached at intermediate shear rates as a result of microbiological processes. The settling velocity was ultimately controlled by aggregate size, capacity dimension, and biomass fraction. Microorganism dynamics including cell motility and food web network interactions significantly controlled aggregate-attached cell abundance and aggregate dynamics.
AB - The genesis of suspended aggregates in aquatic ecosystems is not only a result of hydrodynamic mineral interactions but also a complex microbial food web network. A microbiological-physical model (BFLOC2) is introduced here to predict aggregate geometry and settling velocity under simultaneous effects of hydrodynamic and biological processes. While minerals can contribute to aggregate dynamics through collision, aggregation, and breakup, living microorganisms can colonize and establish food web interactions that involve growth and grazing, and modify the aggregate structure. The BFLOC2 model describes the aggregate dynamics resulting from interactions between minerals and three types of microorganisms, namely bacteria, flagellates, and ciliates. BFLOC2 was first calibrated against the size and capacity (fractal) dimension of aggregates formed in a pure mineral system at different mineral concentrations and fluid shear rates, and then against the abundance of aggregate-attached cells in a pure microbial environment. BFLOC2 model and calibrated parameters were then tested against biomineral aggregate size, capacity dimension, and biomass fraction formed in biomineral flocculation experiments at four nutrient concentrations. Modelling of biomineral aggregate dynamics over a wide range of environmental conditions showed that maximum aggregate size, biomass fraction, and settling velocity could occur at different optimal environmental conditions. Unlike mineral aggregates, which have maximum size when shear rate tends to zero, a relative maximum size of biomineral aggregates can be reached at intermediate shear rates as a result of microbiological processes. The settling velocity was ultimately controlled by aggregate size, capacity dimension, and biomass fraction. Microorganism dynamics including cell motility and food web network interactions significantly controlled aggregate-attached cell abundance and aggregate dynamics.
UR - http://www.scopus.com/inward/record.url?scp=85049336245&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2018.06.247
DO - 10.1016/j.scitotenv.2018.06.247
M3 - Article
C2 - 30189555
AN - SCOPUS:85049336245
SN - 0048-9697
VL - 643
SP - 1387
EP - 1399
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -