12.5. Questions and Tasks
255
kg610eat = if Biomass_30plus Biomass_1029 > = Kg_Urchin_consumed then
Kg_Urchin_consumed*rel_dens 2 {kg urchin}
else if Biomass_30plus < Kg_Urchin_consumed and
Biomass_1029< Kg_Urchin_consumed then t otal_Wt 2 else 0
{kilograms per month }
number610eaten = kg610eat /Ave_Wt2 {urchin}
rel_dens2 = if total_Wt2 and Biomass_1029 > 0 then
total_Wt2 /Biomass_1029 else 0 {unitless}
total_Wt2 = Ave_Wt2*Urchin_610 {kg}
tto_2 = 14 {month}
Urchins05
dead1(t) = dead1(t-dt) + (die1) * dt
INIT dead1 = 0 {urchin}
INFLOWS:
die1 = (Urchins_05*nat_death_rate) {urchin/month}
Urchins_05(t) = Urchins_05(t-dt) + (Recruit-to_610die1) * dt
INIT Urchins_05 = 50000 {urchin}
INFLOWS:
Recruit = Repro_Urchins *RecruitRate {urchin/month}
OUTFLOWS:
to_610 = (Urchins_05-die1) /tto {urchin/month}
die1 = (Urchins_05*nat_death_rate) {urchin/month}
AveWt1 = 1.62e-5 {kg /urchin}
Biomass1029_consumed = Urchin_610 + Urchin_1115 +
Urchins_1620 + Urchins_2125
Biomass_30plus_consumed = Urchins_3135 + Urchin_3640 +
Urchins_4145 + Urchins_4650 + Urchins_5155 +
Urchins_5660 + Urchins_60plus
nat_death_rate = .0025 {urchins per urchins per month}
RecruitRate = .003 {urchins per urchin per month}
Repro_Urchins = Urchin_1115 + Urchins_1620 +
Urchins 2125 + Urchins_26 30 + Urchins_3135 +
Urchins_4145 + Urchins_4650 + Urchins_5155 +
Urchins_5660 + Ur chins_60plus
Total_Urchins = Urchins_05 + Urchin_610 + Urchin_1115 +
Urchins_1620 + Urchins_2125 + Urchins_2630 +
Urchins_3135 + Urchin_3640 + Urchins_4145 +