NONLINEAR NON-EQUILIBRIUM PATTERN FORMATION IN A SPATIAL AQUATIC SYSTEM: EFFECT OF FISH PREDATION

2010 ◽  
Vol 18 (01) ◽  
pp. 129-159 ◽  
Author(s):  
RANJIT KUMAR UPADHYAY ◽  
N. K. THAKUR ◽  
B. DUBEY
Keyword(s):  
Pattern Formation ◽  
Fish Predation ◽  
Aquatic System ◽  
System Effect ◽  
Type Iv ◽  
System A ◽  
Predator Response ◽  
Spatio Temporal ◽  
Equilibrium Pattern ◽  
Non Equilibrium

An attempt has been made to introduce the mathematical modeling of nonlinear non-equilibrium spatio-temporal pattern formation in a minimal model of a spatial aquatic system. A hybrid model of the spatio-temporally continuous phytoplankton-zooplankton system with Holling type IV predator response but discrete agents like fish dynamics has been presented. The model has been investigated for plankton patch formation, which is known from natural plankton populations. Fish predation has a significant role in the temporal evolution of spatial pattern of phytoplankton-zooplankton system, which suggests that unstable diffusive system can be made stable by increasing the rate of fish predation and diffusivity constant to sufficiently large values.

DIFFUSION-DRIVEN INSTABILITIES AND SPATIO-TEMPORAL PATTERNS IN AN AQUATIC PREDATOR–PREY SYSTEM WITH BEDDINGTON–DEANGELIS TYPE FUNCTIONAL RESPONSE

2011 ◽  
Vol 21 (03) ◽  
pp. 663-684 ◽  
Author(s):  
RANJIT KUMAR UPADHYAY ◽  
N. K. THAKUR ◽  
V. RAI
Keyword(s):  
Pattern Formation ◽  
Spatial Heterogeneity ◽  
Collective Motion ◽  
Temporal Dynamics ◽  
Fish Predation ◽  
Building Blocks ◽  
Aquatic System ◽  
Predator Species ◽  
Predator Prey ◽  
Spatio Temporal

Predator–prey communities are building blocks of an ecosystem. Feeding rates reflect interference between predators in several situations, e.g. when predators form a dense colony or perform collective motion in a school, encounter prey in a region of limited size, etc. We perform spatio-temporal dynamics and pattern formation in a model aquatic system in both homogeneous and heterogeneous environments. Zooplanktons are predated by fishes and interfere with individuals of their own community. Numerical simulations are carried out to explore Turing and non-Turing spatial patterns. We also examine the effect of spatial heterogeneity on the spatio-temporal dynamics of the phytoplankton–zooplankton system. The phytoplankton specific growth rate is assumed to be a linear function of the depth of the water body. It is found that the spatio-temporal dynamics of an aquatic system is governed by three important factors: (i) intensity of interference between the zooplankton, (ii) rate of fish predation and (iii) the spatial heterogeneity. In an homogeneous environment, the temporal dynamics of prey and predator species are drastically different. While prey species density evolves chaotically, predator densities execute a regular motion irrespective of the intensity of fish predation. When the spatial heterogeneity is included, the two species oscillate in unison. It has been found that the instability observed in the model aquatic system is diffusion driven and fish predation acts as a regularizing factor. We also observed that spatial heterogeneity stabilizes the system. The idea contained in the paper provides a better understanding of the pattern formation in aquatic systems.

scholarly journals Importance of Holotoxin Assembly in Ptl-Mediated Secretion of Pertussis Toxin from Bordetella pertussis

2000 ◽  
Vol 68 (7) ◽  
pp. 4049-4054 ◽  
Author(s):  
Karen M. Farizo ◽  
Theresa Huang ◽  
Drusilla L. Burns
Keyword(s):  
Pertussis Toxin ◽  
Bordetella Pertussis ◽  
Structural Components ◽  
Type Iv ◽  
System A

ABSTRACT We examined the structural components of pertussis toxin that are required for efficient export from Bordetella pertussis via the Ptl system, a member of the type IV family of macromolecular transporters. First, we constructed a strain of B. pertussis that contains a functional Ptl system but does not produce pertussis toxin. Plasmids which express either the S1 subunit or the B oligomer were then introduced into this strain. We found that the B oligomer of the toxin is not secreted in the absence of the S1 subunit. Conversely, the S1 subunit is also not secreted by a Ptl-mediated mechanism in the absence of the B oligomer. Thus, an assembled holotoxin is required for Ptl-mediated export of pertussis toxin from B. pertussis.

scholarly journals Collective non-equilibrium dynamics at surfaces and the spatio-temporal edge

2012 ◽  
Vol 100 (4) ◽  
pp. 46004 ◽  
Author(s):  
M. Marcuzzi ◽  
A. Gambassi ◽  
M. Pleimling
Keyword(s):  
Equilibrium Dynamics ◽  
Spatio Temporal ◽  
Non Equilibrium
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