Population dynamics of sinking phytoplankton in light-limited environments: simulation techniques and critical parameters
In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101; e-ISSN 1873-1414, more Also appears in:Philippart, C.J.M.; Van Raaphorst, W. (Ed.) (2002). Structuring Factors of Shallow Marine Coastal Communities, part I. Journal of Sea Research, 48(2). Elsevier Science: Amsterdam. 81-172 pp., more |  |
| Keywords | Algal blooms
Biological production
Computation
Dimensions > Depth
Equations
Layers > Water column > Mixed layer
Physics > Mechanics > Fluid mechanics > Fluid dynamics
Trade
Transport processes > Diffusion
Turbulence
Marine/Coastal | | Author keywords | Harmful algal blooms; Computational Fluid Dynamics (CFD); Numerieke stromingsleer; Export production; Mixed-layer depth; Reaction-diffusion equation |
| Abstract | Phytoplankton use light for photosynthesis, and the light flux decreases with depth. As a result of this simple light dependence, reaction-advection-diffusion models describing the dynamics of phytoplankton species contain an integral over depth. That is, models that simulate phytoplankton dynamics in relation to mixing processes generally have the form of an integro-partial differential equation (integro-PDE). Integro-PDEs are computationally more demanding than standard PDEs. Here, we outline a reliable and efficient technique for numerical simulation of integro-PDEs. The simulation technique is illustrated by several examples on the population dynamics of sinking phytoplankton, using both single-species models and competition models with several phytoplankton species. Our results confirm recent findings that Sverdrup's critical-depth theory breaks down if turbulent mixing is reduced below a critical turbulence. In fact, our results show that suitable conditions for bloom development of sinking phytoplankton depend on a number of critical parameters, including a minimal depth of the thermocline, a maximal depth of the thermocline, a minimal turbulence, and a maximal turbulence. We therefore conclude that models that do not carefully consider the population dynamics of phytoplankton in relation to the turbulence structure of the water column may easily lead to erroneous predictions. |
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