Modelling the extintion of Steller Sea Cow

Modelling the extintion of Steller Sea Cow preview image

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Colors Laura Bonatesta (Author)

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complex modelling 

Tagged by Laura Bonatesta about 6 years ago

exintion 

Tagged by Laura Bonatesta about 6 years ago

modelling ecosystem 

Tagged by Laura Bonatesta about 6 years ago

predator prey model 

Tagged by Laura Bonatesta about 6 years ago

sea otter 

Tagged by Laura Bonatesta about 6 years ago

steller sea cow 

Tagged by Laura Bonatesta about 6 years ago

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globals [ks kk ku kl kcatch rs ru rk ro rcatch catchers-start mu sea-urchins-start mu2 sea-otters-start zone land sea] ; le variabili globali che non possono variare, vengono dichiarate all'inizio del sistema.

breed [seacows seacow] ; definisce un nuovo tipo di turtle: le seacows, il soggetto della caccia da parte dei predatori
breed [catchers catcher]; definisce un nuovo tipo di turtle: i cacciatori, gli uomini bloccati sull'isola di Bering
breed [sea-urchins sea-urchin]; definisce un nuovo tipo di turtle: i sea-urchins, rivali alle retine per il loro cibo di sostentamento, ovvero le kelps.
breed [kelps kelp]; definisce un nuovo tipo di turtle: le kelps, cibo sia delle seacows che dei sea-urchins
breed [sea-otters sea-otter]; 
catchers-own [n-of-preys]; le variabili proprie dei catchers, dei cacciatori.
sea-urchins-own [n-of-preys]; la variabile dei sea-urchins

to setup
 ;; (for this model to work with NetLogo's new plotting features,
  ;; __clear-all-and-reset-ticks should be replaced with clear-all at
  ;; the beginning of your setup procedure and reset-ticks at the end
  ;; of the procedure.)
  __clear-all-and-reset-ticks
 set-default-shape seacows "seacow" ; definisce la forma che il programma deve utilizzare per rappresentare la seacow di steller (modificata dall'autore ed inserita)
 set-default-shape catchers "sailboat side"; definisce la forma che il programma deve utilizzare per rappresentare i cacciatori (presenta all'interno della Library del programma) 
 set-default-shape sea-urchins "urchin"; this input defines the shape of the sea-urchins (modified by the autor and inserted in the library)
 set-default-shape kelps "kelp"; this input defines the shape of the kelp (modified by the author and inserted in the library)
 set-default-shape sea-otters "squirrel"; per la lontra è stta utilizzata la forma dello scoiattolo, già esistente nella libreria. la forma è stata ruotata di alcuni gradi per assomigliare alle lontre che sono sempre ruotate sul loro dorso. 
 set catchers-start 30; 
 set kcatch 65
 set ks 2900; 
 set kk 4000; 
 set ku 4000;
 set rs 0.0135;
 set rk 0.0061; 
 set ru 0.0015;ricci
 set ro 0.0020; lontre
 set rcatch 0.02631
 set mu 0.60; mu represents the mortality of the catchers. this could be a realistic value because many people died for famine
 set mu2 0.65; mu2 mortalità dei ricci

 create-catchers catchers-start [ ; this input crates the turtle of the catchers and the value of start is declared before
  set color red; this input sets the color of the turtle
  set size 2;this input sets the size of the boat
  setxy random-xcor random-ycor; this inputs sets the position of the turtle in the space, but it's indifferent for that the position is decised randomly by the program. 
 ]
 
 create-seacows ks [;this input creates the turtle of the seacows and the value k at the start that is 200 
  set color grey;this command sets the color for the turtle
  set size 3; this input sets the size, I've choose 3 bacause the seacows were bigger than the humans
  setxy random-xcor random-ycor; they used to live everywhere, it's indifferent if near the shore or in the deepest water, for that the program is setted on random
 ]

; ; if the switch "variable" is switched on this inputs reads the command in the firts brackets creating the kelps
    create-kelps Kk[;this procedure creates the kelp, with the value k2 setted above, the color green, the size and the position.
    set color green
    set size 1
    setxy random-xcor random-ycor
 ]  
    
; if the switch "variable2" of the Interface is switched on this inputs reads the command in the first brackets, otherwise the second.
    create-sea-urchins Ku[; this procedure creates the sea-urchins, with the value k3 setted next, the colorblack, the size and the position.
    set color magenta
    set size 0.5
    setxy random-xcor random-ycor
 ]
    
  ifelse seaotters = true [set Kl 2500] [set Kl 0]; ; if the switch "variable" is switched on this inputs reads the command in the firts brackets creating the kelps
    create-sea-otters Kl [;this procedure creates the kelp, with the value k4 setted above, the color green, the size and the position.
    set color brown - 2
    set size 1
    setxy random-xcor random-ycor
 ]  
 
 ask patches [
 set pcolor blue
 ]
end 

to go
  tick 
  move-seacows; it makes move the seacows
  move-catchers; it makes move the cathcers
  move-kelps; it makes move the kelpe
  move-sea-urchins; it makes move the sea-urchins
  move-sea-otters;
  catch; the catch of the retine by the catchers and the catch of the kelpe by the sea-urchins and the seacows
  reproduce; the reprodcution of the catchers after the hunt
  reproduce2; the reproduction of the sea-urchins after the hunt
  reproduce3;
  do-plots; the value for the monitor in the page of the interface
  if ticks = 27 [stop]; ticks represents the time; this case occupied 27 years, every tick for a year
end 

to move-seacows ; it makes moves the seacows in the screen, random in the space. fd 1 means 1 step forward
  ask seacows [
  set heading random 360
  fd 1
] 
end 

to move-catchers; it makes moves the catchers, random in the space. fd 1 means 1 step fprward
 ask catchers [
   set heading random 360   
   fd 1
   set n-of-preys 0; it's own variable of the catchers. it means that every year is like a season of hunt
]  
end 

to move-kelps; it makes move kelpe, random in the screen. fd 1 means 1 step forward
  ask kelps [
  set heading random 360
  fd 1 
]
end 

to move-sea-urchins; it makes move the sea-urchins, random in the space. fd 1 means 1 step forward
  ask sea-urchins [
   set heading random 360
   fd 1
 ]
end   

to move-sea-otters; it makes move the sea-urchins, random in the space. fd 1 means 1 step forward
  ask sea-otters [
   set heading random 360
   fd 1
 ]

  do-plots 
end     

to catch
  ask catchers [
    ifelse any? sea-urchins in-radius catch-distance
    [
      let to-catch [who] of sea-urchins in-radius catch-distance
      foreach to-catch [
          ask sea-urchin ? [die]
      set n-of-preys n-of-preys + 1
      ]
    ]
  [
    if any? sea-otters  in-radius catch-distanceb 
      [ 
        let to-catch [who] of sea-otters in-radius catch-distanceb  
        foreach to-catch [  
          ask sea-otter ? [die]
          set n-of-preys n-of-preys + 0.5
        ]
      ]    
    ]
  ]
  ask catchers [
    if any? seacows in-radius catch-distance
    [ 
      let to-catch [who] of seacows in-radius catch-distance  
      foreach to-catch [ 
        ask seacow ? [die]
        set n-of-preys n-of-preys + 2
      ]
    ]
      if any? sea-otters  in-radius catch-distanceb 
      [ 
        let to-catch [who] of sea-otters in-radius catch-distanceb  
        foreach to-catch [  
          ask sea-otter ? [die]
          set n-of-preys n-of-preys + 0.5
        ]
      ]    
    ]
  ask catchers [
    if any? sea-urchins in-radius catch-distance
    [
      let to-catch [who] of sea-urchins in-radius catch-distance
      foreach to-catch [
          ask sea-urchin ? [die]
      set n-of-preys n-of-preys + 1
      ]
    ]
  ]
  ask seacows [ ; ask seacows
    if any? kelps in-radius catch-distance2; if there are some sea-urchins in their radius of catch distance (catch distance3) 
    [
      let to-catch [who] of kelps in-radius catch-distance3; and catch the kelpe in the radius
      foreach to-catch [
          ask kelp ? [die]
        ]
       ]
     ] 
  ask sea-urchins [
    if any? kelps in-radius catch-distance3; 
     [ 
      let to-catch [who] of  kelps in-radius catch-distance ; the sea  
      foreach to-catch [ ; for each item "captured"
          ask kelp ? [die] ; ask to the turtle shaped like an alga to die
          set n-of-preys n-of-preys + 1 ;  when a  
          ]
        ]
      ] 
  ask sea-otters [ ; ask seacows
    if any? sea-urchins in-radius catch-distance4; if there are some sea-urchins in their radius of catch distance (catch distance3) 
    [
      let to-catch [who] of sea-urchins in-radius catch-distance4; and catch the kelpe in the radius
      foreach to-catch [
          ask sea-urchin ? [die]
        ]
       ]
     ]    
end 

to reproduce

let new-seacows round (rs * count seacows * ( 1 - (count seacows) / ks))
create-seacows new-seacows [setxy random-xcor random-ycor set color grey]

let new-catchers round (kcatch * count catchers * ( 1 - (count catchers) / kcatch))
    create-catchers new-catchers [setxy random-xcor random-ycor set color red set size 1]

  ask catchers [ ; the probability to die for the catcher estimed by the mu
    if random 1001 / 1000 < mu [die]
  ]
end 

to reproduce2

  let new-kelps round (rk * count kelps * ( 1 - (count kelps) / kk))
  create-kelps new-kelps  [setxy random-xcor random-ycor set color green]
  
  ask sea-urchins [ ;each sea-urchins creates as many copies of itself as half (n-of-preys/5) of the kelpe caught in season
    hatch round (n-of-preys / 4) [setxy random-xcor random-ycor]
  ]
  ask sea-urchins [ ;  the probability to die for the sea urchin its evaluated by the mu
    if random 1001 / 1000 < mu2 [die]
  ]
end 

to reproduce3
ifelse seaotters = true [
let new-sea-otters round (ro * count sea-otters * ( 1 - (count sea-otters) / kl))
  create-sea-otters new-sea-otters [setxy random-xcor random-ycor set color brown - 2  set size 2] 

  ask catchers [ ; each catchers creates as many copies of itself as half (n-of-preys/1) of the sea-otters caught in season; the catcehrs' reproduction depenends on the hunt of the season  
    hatch round (n-of-preys / 2) [setxy random-xcor random-ycor]
  ]
  ask catchers [ ; the probability to die for the catcher estimed by the mu
    if random 1001 / 1000 < mu [die]
  ]
]
[let new-seaotters 0]
end 

to do-plots
  set-current-plot "populations" ; plot of the two lead population: seacows and catchers 
  set-current-plot-pen "seacow" ; this command defines the pen "seacows" colured in grey in the monitor in the interface
  plot count seacows
  set-current-plot-pen "catchers";this command defines the pen "catchers" colured in red in the monitor in the page Interface
  plot count catchers
  set-current-plot-pen "sea-urchins";this command defines the pen "sea-urchins" colured in black in the forst monitor in the page Interface
  plot count sea-urchins
  set-current-plot-pen "kelps"; this command defines the pen "kelpe" in the first page inteface, colured in green
  plot count kelps
  set-current-plot-pen "sea-otters"
  plot count sea-otters 
  set-current-plot "status"; the monitor at the bottom of the page, the first dedicated to the population of retine and catchers, the second to the kelpe and the sea-urchins
  plotxy count seacows count catchers
  set-current-plot "status 2"
  plotxy count kelps count sea-urchins
  set-current-plot "status 3"
  plotxy count sea-otters count catchers
  plot count sea-otters 
end 

There is only one version of this model, created about 6 years ago by Laura Bonatesta.

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