Rebalancing 121 Rebalancing Human-Influenced Ecosystems YuanSi Zhang ShuoPeng Wang 1g Dept of Mathematics China university of Mining and Technology Advisor: Xingyong Zhang Summary populations. Then, based on the Analytic Hierarchy Process and a competi tionmodel, we obtain the ratio of different species in the second population, water quality satisfactory by adjusting the juality is nothigh, and make the predict that the steady-state level of wat numbers of six species In Task 2, when milkfish farming suppresses other animal species, we set up a logistic model, and predict that the water quality at steady-state is awful, the same as in the fish pens--insufficient for the continued healthy growth of coral species. When other species are not totally suppressed, with an improved predator-prey model we simulate the water quality of Bolinao(makingitmatch current quality), obtainpredictednumbers of pop ulations, and discuss changes to the predator-prey model aimed at making the numbers of the populations agree more closely with observations n Task 3, we establish a polyculture model that reflects an interdepend dent set of species, introduce mussels and seaweed growing on the sides of the pens, and obtain the numbers of populations in steady state and the outputs of or In Tasks 4 and 5, we differentiate the monetary values of different kind edible biomass and define the total value as the sum of the values of each species harvested, minus the cost of milkfish feed. Under circumstances The UMAP Jouna130(2)(2009)121-139. @Copyright 2009 by COMAP Inc. Allrights reserved Permission to make digital or hard copies of part or all of this work for personal or classroom use tt fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice. Abstracting with credit is permitted, but copyrights for components of this work owned by others than COMAP must be honored. To copy otherwise, to republish, to post on servers, or to redistribute to lists requires prior permission from COMAPRebalancing 121 Rebalancing Human-Influenced Ecosystems YuanSi Zhang ShuoPeng Wang Ning Cui Dept. of Mathematics China University of Mining and Technology Xuzhou, Jiangsu, China Advisor: Xingyong Zhang Summary In Task 1, we establish a Volterra predator-prey model with three bio￾logical populations, and we specify the steady-state numbers of the three populations. Then, based on the Analytic Hierarchy Process and a competi￾tion model, we obtain the ratio of different species in the second population, predict that the steady-state level of water quality is not high, and make the water quality satisfactory by adjusting the numbers of six species. In Task 2, when milkfish farming suppresses other animal species, we set up a logistic model, and predict that the water quality at steady-state is awful, the same as in the fish pens-insufficient for the continued healthy growth of coral species. When other species are not totally suppressed, with an improved predator-prey model we simulate the water quality of Bolinao (making it match current quality), obtain predicted numbers of pop￾ulations, and discuss changes to the predator-prey model aimed at making the numbers of the populations agree more closely with observations. In Task 3, we establish a polyculture model that reflects an interdepen￾dent set of species, introduce mussels and seaweed growing on the sides of the pens, and obtain the numbers of populations in steady state and the outputs of our model. In Tasks 4 and 5, we differentiate the monetary values of different kinds edible biomass and define the total value as the sum of the values of each species harvested, minus the cost of milkfish feed. Under circumstances The UMAPJournal30 (2) (2009)121-139. QCopyright2009byCOMAP, Inc. All rights reserved. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice. Abstracting with credit is permitted, but copyrights for components of this work owned by others than COMAP must be honored. To copy otherwise, to republish, to post on servers, or to redistribute to lists requires prior permission from COMAR