An aquatic model consists of nutrient, phytoplankton and zooplankton has been developed. The hyperbolic form of mortality for zooplankton has been used. The complex behavior of the system is observed in case of fluctuating input nutrient in the system. The extensive numerical investigation revealed the variations in periodic orbits for some sensitive parameters. The short term oscillations has been also observed. The amplitudes of oscillatory orbits have been found at different nutrient input concentrations.

1. A. M. Edwards and J. Brindley, Oscialltory behavior in a threecomponent plankton population model. Dyn. Stablity Systems 11, no. 2 (1996): 347-370.
2. A. M. Edwards and J. Brindley, Zooplankton mortality and the dynamical behavior of plankton population models. Bull. Math. Biol. 61, no. 2 (1999): 303-339.
3. A. M. Edwards, "Adding detritus to a nutrient-phytoplanktonzooplankton model: a dynamical-systems approach" Evolutionary Ecology 8, no. 2 (2001): 389.
4. A. M. Edwards, and M. A. Bees, "Generic dynamics of a simple plankton population model with a non-integer exponent of closure. " Chaos, Solitons & Fractals 12,no. 2 (2001): 289-300.
5. G. T. Evans and J. S. Parslow, A model of annual plankton cycles. Bio. Oceanogr. 3, (1985): 327-427.
6. B. W. Frost, Grazing control of phytoplankton stock in the open sub-arctic Pacific Ocean. . . . Mar. Ecol. Ser. 39, (1987): 49-68.
7. G. A. Riley, H. Stommel and D. p. Burrpus, Qualitative ecology of the plankton of the Western North Atlantic. Bull. Binghm Oceanogr. Collect. 12, (1994): 1-169.
8. J. H. Steel, Strututre of Marine Ecosystems. Oxford: Blackbell Scientifics. 1964.
9. J. H. Steel and B. W. Frost, Strututre of Plankton communities. Phill. Trans. R. Soc. London. B280, 485-534.
10. J. H. Steel and E. W. Henderson, A simple plankton model. American Naturalist 117, (1981): 676-691.
11. J. H. Steel and E. W. Henderson, The role of predation in plankton models. Journal of Plankton Res. 14, (1992): 157-172.
12. A. J. Taylor, Characteristic properties of model for the vertical distributions of phytoplankton under stratification. Ecol. Modelling. 40, (1988): 175-199.
13. J. S. Wroblewski, An ocean basin scale model of phytoplankton dynamics in the North Atlantic. Solution for the climatological oceanographic condition in May. Global Biogeochem 2, (1988): 199-218.

Plankton System Hopf-bifurcation Periodic Orbits