2012 journal article
A Lagrangian model for phototaxis-induced thin layer formation
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 101, 193–206.
author keywords: Phytoplankton; Diurnal vertical migration; Mixed layer; Turbulence; Lagrangian model
open access via manuscript.elsevier.com (publisher PDF)
UN Sustainable Development Goal Categories
13. Climate Action
(Web of Science)
14. Life Below Water
(Web of Science; OpenAlex)
Source: Web Of Science
Added: August 6, 2018
We have developed a Lagrangian model to investigate a potential mechanism based on phototaxis behavior of phytoplankton cells for the formation of thin layers. We assume that all cells follow a time-regulated diurnal vertical migration during which they experience photo-acclimation based on the Denman and Marra (1986) model. When a cell experiences stress due to strong light that exceeds a threshold level, the cell swims downward, away from the light. We applied the Lagrangian model to a one dimensional second order turbulence closure model that generates a realistic surface mixing condition for a given set of physical parameters, such as wind and optical water type. For the chosen swimming velocities and prescribed behavior, we found that, in coastal water type and Jerlov III type, thin layer formation takes place up to 5 m s−1 winds, while 10 m s−1 winds cause sufficiently strong mixing to prevent the formation of thin layer. We have also investigated the effects of changing the irradiance threshold for the onset of the photoinhibition, the initial density profile and random walk swimming. In conclusion, thin layer formation due to photoinhibition may be possible for a low value of photoinhibition threshold that may occur either due to upwelling or strong light exposure.