MIHS MEL FINAL OCEAN ACIDIFICATION

1 collaborator

Mel Bph (Author)

Maggie Baker, Libby Hetzel, Ellie Park. Period 3 Biology

WHAT IS IT?

Our model demonstrates the relationship between the level of carbon dioxide (CO2) in the water and marine life (specifically shellfish and a predator species of fish). As our model shows, when CO2 in the water is increased, the population of shellfish dies down. In real life, the increased death rates of shellfish can be explained by the degradation of their shells, due to the increased acidity of the water, which is a result of increased CO2 content. Without the protection of their shells, shellfish are left vulnerable to predators and rough ocean conditions, causing their mortality rate to increase drastically. Our model also demonstrates how the dramatic decrease in the shellfish population affects larger predator species of fish who rely on the shellfish as a food source. When the shellfish population is decreased, the larger fish don't have a sufficient food supply and so their mortality rate increases as well. This whole interconnected system is represented through our Netlogo model.

HOW IT WORKS

In our model, there are two different kinds of turtles: shellfish and larger predator fish. The way we got the shellfish population to decrease with increasing CO2 levels in the water was by having green tiles (the CO2) zap shellfish whenever they land on them. This way, the health of the individual shellfish decreases and eventually, if they reach a health of "0," they will die. With this system, more green patches (or CO2) makes it more likely for shellfish to be zapped and die. Also, the blue tiles serve as food for the shellfish, so with more green and less blue, shellfish populations will decrease since they won't be able to get enough energy. In turn, the shellfish act as a food source for larger predator fish in this model, so when the shellfish population is low the predator fish population will decrease as well since they won't be getting enough food and energy to survive.

HOW TO USE IT

Click start, then go. You can change the settings of how many fish and shellfish there are and how much CO2 is in the ocean (represented by green tiles). You can change these with the sliders.

THINGS TO NOTICE

Notice how the shellfish behave differently and how their reproduction is different when the pH is manipulated. Notice that either that everything dies out or that only the shellfish survive.

THINGS TO TRY

Try changing the pH and the numbers of the animals.

EXTENDING THE MODEL

One cool thing to change in the code is the reproduction rate and things about their health. Change the amount of heath that a turtle starts with and how much it gains and loses in certain situations.

RELATED MODELS

We created this model on our own, but used the wolf and sheep model for guidence on some parts.

Comments and Questions

Please start the discussion about this model! (You'll first need to log in.)

Click to Run Model

breed [predators predator]
breed [shells shell]
turtles-own [health]

to setup
  clear-all
  setup-patches
  setup-predators
  setup-shells
  reset-ticks
end 

to go
  if ticks >= 1000000 [ stop ]
  move-predators
  move-shells
  check-death
  reproduce
  tick
end 

to setup-patches
  ask patches [ set pcolor blue ]
  ask patches [if random 100 < pH [ set pcolor green ]]
end 

to setup-predators
  create-predators number[ set health 100 setxy random-xcor random-ycor set shape "fish" set color orange fd random 10 ]
end 

to setup-shells
  create-shells number[ set health 100 setxy random-xcor random-ycor set color white set shape "dot" fd random 10 ]
end 

to move-predators
  ask predators [
    catch-shells
    right random 360
    forward 1
    rt random 20
    lt random 20
    set health health - 1
  ]
end 

to move-shells
   ask shells [
    eat-grass
    right random 160
    forward 1
    rt random 20
    lt random 20
    set health health - 1
   ]
end 

to reproduce
  ask turtles [
  if health > 50 [
    if random 100 < 5 [
    set health health - 5
    hatch 1 [ set health 50 ]
    ]
  ]
]
end 

to check-death
  ask turtles [
    if health <= 0 [ die ]
  ]
end 

to eat-grass
    if pcolor = blue [
      set pcolor blue
      set health health + 15
    ]
    if pcolor = green [
      get-zapped
    ]
  ifelse show-health?
  [ set label health ]
  [ set label "" ]
end 

to catch-shells
  let prey one-of shells-here
  if prey != nobody
    [ ask prey [ die ]
       set health health + 10 ]
end 

to get-zapped
  set health health - 10
end

There is only one version of this model, created over 8 years ago by Mel Bph.

Attached files

File	Type	Description	Last updated
MIHS MEL FINAL OCEAN ACIDIFICATION.png	preview	Preview for 'MIHS MEL FINAL OCEAN ACIDIFICATION'	over 8 years ago, by Mel Bph	Download

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