Understanding the transport feature of bloom-forming Microcystis in a large shallow lake: A new combined hydrodynamic and spatially explicit agent-based modelling approach
Authored by Chao Wang, Tao Feng, Peifang Wang, Jun Hou, Jin Qian
Date Published: 2017
DOI: 10.1016/j.ecolmodel.2016.10.017
Sponsors:
Chinese National Natural Science Foundation
National Science Fund for Distinguished Young Scholars
National Science Funds for Creative Research Groups of China
Platforms:
No platforms listed
Model Documentation:
ODD
Mathematical description
Model Code URLs:
Model code not found
Abstract
Understanding the complex transport feature of phytoplankton is
important for predicting bloom forming process. In this study, a coupled
hydrodynamic and agent-based approach is developed to characterise the
transport behaviour of colony-forming Microcystis in a large shallow
lake. Two models are combined: a hydrodynamic model to offer a basic
flow field, and an agent-based model to incorporate the physiological
response (buoyancy-controlling strategies) and migratory behaviour
(horizontal advection and random-walk vertical mixing) of Micorcystis.
The Meiliang Bay in Lake Taihu, which experiences high Microcystis
blooms every year, was chosen as a case study to test the performance of
this coupled approach. By comparing our coupled model with available
field measurement, our results can reproduce changes in buoyancy status
and three-dimensional distribution exposures to different wind
intensities. Meanwhile, our coupled model shows more accurate results
than the simulated results from traditional Eulerian approach. In
shallow lake systems, strong wind (>6 m/s) can easily mix water column
and keep most colonies buoyant. Subsequent gentle wind (<3 m/s) causes
more intensive horizontal accumulation of these buoyant Microcystis in
the downwind area than what happens under strong wind. Small colonies
are readily dispersed by wind-induced turbulence and homogenized by
local current circumstances. Diurnal temporary stratification and large
colony sizes contribute to surface patches formation and downwind
migration, leading to the heterogeneity of Microcystis bloom under the
integrated effect of surface currents and wind drift. Therefore, the
transport pattern of Microcystis colonies is a dynamic balance between
turbulence and wind drift, along with buoyancy which is related to
colony size. Overall, our combined model could be used to characterise
the detailed movement patterns of Microcystis colonies or patches in
large shallow lakes. (C) 2016 Elsevier B.V. All rights reserved.
Tags
China
Phytoplankton
transport behaviour
Wind
Vertical-distribution
Eulerian and agent-based coupled model
Microcystis
bloom
Lake taihu
Kutz-emend-elenkin
Eutrophic lake
Cyanobacterial blooms
Buoyancy regulation
Aeruginosa
Taihu