An individual-based analysis of the dynamics of two coexisting phytoplankton species in the mixed layer
Authored by Daniela Cianelli, Enrico Zambianchi, Luciana Sabia, Maurizio Ribera d'Alcala
Date Published: 2009
DOI: 10.1016/j.ecolmodel.2009.06.016
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Abstract
In marine ecosystems ecological and environmental conditions
continuously change, possibly supporting the wide range of phytoplankton
species coexisting in aquatic environments. Phytoplankton communities
are not homogeneously distributed in the water column due to the spatial
and temporal variability of turbulent mixing and the concurrent
biological response. In this paper an individual-based model (Lagrangian
method) simulating the basic physiology of two coexisting phytoplankton
species has been developed. The species, sharing the same availability
of light and nutrient resource, are characterized by different
photo-physiological parameters. The spatial and temporal evolution of
turbulent mixing is simulated introducing vertical profiles of measured
eddy diffusivity. Three case studies have been examined to analyze the
role of environment-individual interactions in determining bloom
conditions for both the selected species. The organisms experience
recurrent fluctuations of light, temperature, and nutrient concentration
gradients, due to the turbulent mixing in the water column, which have
significant effects on the growth of the phytoplankton species. In all
the numerical experiments, the temporal and spatial variability of
different forcings do not support the prevalence of one species over the
other over the time scale typical of a phytoplankton bloom.
A well mixed water column favours the growth of both the populations
while a variable mixing regime limits their growth reducing the
photophysiological differences between the species. (C) 2009 Elsevier
B.V. All rights reserved.
Tags
Resource competition
Light
growth
Water column
Random-walk models
Sea
Variable environment
Nutrient-limitation
Lagrangian approach
Turbulent flows