Rebalancing 129 Concentrations of elements in a pen, Element Concentration(ug/L) c(10%) 119174 P06%) Comparing the water quality in Sites A, B, C, and D, we find that the concentration of organics is between A and B, which is suitable for the growth of coral (here the concentration of elements is calculated only based in the excrement of milkfish and echinoderm), so the concentration of the microbes meets the reproduction needs of the coral. But the concentration of chlorophylls seriously out oflimits So we have to adjust thenumbers of some species to make the concentration of chlorophyll reach the standard We reason backward from the desired concentration(0. 25 Ag/L) of chlorophyll suitable for the growth of the coral, using the regression equa tion(1). With the estimated steady-state value, we can assume the initial values as:(10000, 5500, 350). From relevant references, we get the maxi- mum volume of fish pens: (N1, N2, N3)=(30000, 6000, 400), and through resimulation finally find the positive revised results for the steady-state val ues:(13732,5432,320). We work out the estimated steady-state number of algae N= 1. 4677, nd then derive the numbers of the three populations: (14677, 5744, 350 After revision, we get the actual steady-state number of the algae: N 1.3732. Putting this value into the regression equation, we getC=0. 125, thatis, the concentration of chlorophylls 0. 125 ug/L, which means that the water quality after adjustment completely meets the standard demanded Moreover, the totalnumber of milkfish and echinoderm is smaller than that before revision,so the index of the organics can certainly reach the growing demands of the coral, as shown in Figure 4 mo o the retroregulation process, which is the feedback mechanism of this del, with known water quality, we reason backwards to the estimated steady-state numbers of all the species, make positive simulation after es- timating the initial introducing value of all the species, and get the revised steady-state values. With this mechanism, we can find out the steady-state number of each species based on water quality, which provides great con- venience to the solution to the following problems Task 2a: Establishment of Logistic Model In this task, with all the herbivorous fish, crustaceans, molluscs, and echinodermsexcluded, we are required to find out the changes to thespecies and the circumstances of water quality. Based on our analysis, we makeRebalancing 129 Table 3. Concentrations of elements in a pen. Element Concentration (psg/L) C (10%) 119-174 N (0.4%) 5- 7 P (0.6%) 7- 10 Comparing the water quality in Sites A, B, C, and D, we find that the concentration of organics is between A and B, which is suitable for the growth of coral (here the concentration of elements is calculated only based on the excrement of milkfish and echinoderm), so the concentration of the microbes meets the reproduction needs of the coral. But the concentration of chlorophyll is seriously out of limits. So we have to adjust the numbers of some species to make the concentration of chlorophyll reach the standard. We reason backward from the desired concentration (0.25 pg/L) of chlorophyll suitable for the growth of the coral, using the regression equa￾tion (1). With the estimated steady-state value, we can assume the initial values as: (10000, 5500, 350). From relevant references, we get the maxi￾mum volume of fish pens: (N1, N2 , N3) = (30000, 6000, 400), and through resimulation finally find the positive revised results for the steady-state val￾ues: (13732,5432,320). We work out the estimated steady-state number of algae N = 1.4677, and then derive the numbers of the three populations: (14677, 5744, 350). After revision, we get the actual steady-state number of the algae: N = 1.3732. Putting this value into the regression equation, we get C = 0.125, that is, the concentration of chlorophyll is 0.125 [g / L, which means that the water quality after adjustment completely meets the standard demanded. Moreover, the total number of milkfish and echinoderm is smaller than that before revision, so the index of the organics can certainly reach the growing demands of the coral, as shown in Figure 4. In the retroregulation process, which is the feedback mechanism of this model, with known water quality, we reason backwards to the estimated steady-state numbers of all the species, make positive simulation after es￾timating the initial introducing value of all the species, and get the revised steady-state values. With this mechanism, we can find out the steady-state number of each species based on water quality, which provides great con￾venience to the solution to the following problems. Task 2a: Establishment of Logistic Model In this task, with all the herbivorous fish, crustaceans, molluscs, and echinoderms excluded, we are required to find out the changes to the species and the circumstances of water quality. Based on our analysis, we make