Model Project Proposal
Comments by: Michael Pennino (in blue)
Comments by John Petersen (in red)
Title: A Heuristic Model of Adelie Penguin and Krill Populations as a function of Sea Ice extent
I think it would be helpful if you mentioned briefly the type of relationship that exists between the penguin, krill and sea ice extent. For instance, “A Heuristic Model of the variations in Adelie Penguin and Krill Population Sizes as a function of se Ice extent”. [This is a good point that Mike is making. I would take it further –, “A heuristic model to explore how sea ice extent affects dynamics between Adelie Penguin and krill populations.”]
Background and problem statement:
Adelie penguins have been studied as an indicator species for ecosystem functions in Antarctica. Because Adelie penguins are obligates ofdependant on the sea ice, variation in sea ice distribution (on an annual basis) can greatly influence colony size. How much sea ice cover exists in a given year will influence the accessibility to foraging areas, prey availably and recruitment. Here By recruitment is we mean the number of juvenile penguins that start to breed in a given year. In addition to directly affecting penguin populations sea ice extent also affects krill populations (. Since Antarctic krill are main food resource for Adelie penguins). , this is also critical to penguin population dynamics. Sea ice extent levels change the structural demographics [define technical population biology jargon] of the population [which population, penguins or krill? This is not clear] by influencing recruitment. For example low ice cover will lead to lower recruitment and smaller krill popAdd Tract changesulations. Maybe you should complete this feedback loop by decribing what you expect to happen once the krill populations decrease and how that will affect the panguin population? Or more details about what you think will happen due to global woarming. Also do you think that the paenquin population has any effect on the amount of sea ice cover? [good points Mike]
The extent that sea ice distribution influences the success of colonies can often be contradictorySea ice distribution can have multiple, sometimes contrasting, effects on the penguin population [sentence awkward as written]. The number of breeding pairs may increase in a year with low ice cover (because reduced ice cover allows for easier access to ice free breeding grounds and increased breeding space) while simultaneously reducing foraging success rates by limiting prey availability [Very awkward sentence structure. Avoid placing critical causal explanations in parentheses. Verb does not agree with subject].
We are interested in making a model that illustrates the point that several allows the user to explore how factors influencee population size and the leads them to an understanding of the interdependency of these factors is important in understanding in community dynamics and . We are also interested in the user developing an unserstanding of how global warming will affect these relationships.
Research or lesson objectives: Our goal is to develop aA heuristic model of the Adelie penguin populations that…. and the interdependency to krill populations as a function of fluxuating sea ice levels would be a useful tool in demonstrating the effects of global warming in the Antarctic ecosystem [this sentence is not stated as an objective]. Even though many of these relationships are very complex within themselves, the interdependency of state variables in this model would be useful for an entry-level biology course such as BIO 120 as a way of looking at community dynamics. I think you should be more specific why describing the interdependency of the state variable in this model will be useful for an entry–level biology coursce [yes]. Potentially the model could also predict to what extent further temperature increases will have on penguin populations. We want to show that the relationship between krill and penguin populations should follow a Lotka-Volterra pattern [does it actually follow these dynamics in nature?]. Variation is sea-ice extent disrupts this pattern and we plan to show how populations are effected [this would be great if you can do this]. This can be taken a step further be creating model simulations that low students to see how populations will behave when global temperature changes the sea ice system.
What is the total area of land coverage you are modeling? How are you going to model the variation is sea ice extent? Is the area or hieght of the ice important? Will you just be modeling the total area of sea ice? How will you model how the sea ice is broken up into different sections? [good questions. Probably best to focus on density in a given area. Since the intent is to create a heuristic model, the absolute extent is not so important]
Key state variables, flows, forcing functions: Adult Penguin, Juvenile Penguins, Adult Krill Populations, Birth / Mortality Rate (for Krill and Penguins), Recruitment Rate (for Krill and Penguins)
Forcing Functions; Maximum Sea Ice Extent (Southern Oscillation Index) and Temperature
Why do you have recruitment rate for Krill if the Krill have not Jouvenile stage?
What about a converters for the flow of the Krill population into the Penguin population as they are being eaten? [feeding rate] Do humans have an impact on any of the dynamics? [If you are basing this on lotka-voltera, then you have a contact rate coefficient (mass-action type formulation), and extent of sea-ice is one of the factors influencing this contact rate]
Responsibilities. We plan to divide the model in to three parts; Adelie penguin populations, Krill Populations and Sea Ice fluctuation in relation to temperature. Each of us will that [take?] one of these variables and construct a simple model for the particular stock. We can then combine the simple models, and work as a group in determining how the variables relate and interact with each other. To set the model up as a learning device, we will each devise a condition under which the model can be run in order to better understand the dynamics of the system. [you might want to research these separately, but I suggest that you work collectively on developing the model. As you describe them, the variables are too related to be developed separately]
Timeline-
4/21- Simple models for each stock and general readings about the subject due
4/29/05– Synthesis of model with all relationships and forcing functions
5/4/05-Lesson component of model assembled
5/10- Formal written report and power point presentation
5/11- Fine-tune oral presentation
General
You do a good job at describing and providing context to the problem. And I get a good general idea of the feedback relationships that are occurring in this model. This looks like a really feasible subject to be modeling. It is not to simple and not too challenging.
Annotated bibliography:
Ainley, D. G. 2002. The Adelie Penguin; Bellwether of Climate Change. Columbia University Press, New York.
This is a cumulative resource of the current data on penguin ecology. It is a good resource for understanding how penguins interact with the sea ice and how sea ice levels behave on different temporal scales.
Ainley, D. G., et al. 2003. Late–Holocene initiation of ice –free ecosystems in the southern Ross Sea, Antarctica. Marine Ecology-Progress Series 262: 19-25.
This study gives broader picture to how temperature affects penguin populations. It shows that as the sea ice levels receded, after the ice age penguin populations increased.
Ainley, D. G., et al. 2001. Adelie penguin population change in the pacific sector of Antarctica; relation to sea ice extent and the Antarctic Circumpolar Current. Marine Ecology-Progress Series 213:301-309. This paper shows the relationship between annual population growth and the extent of ice cover. This is useful in defining (and giving values to) our forcing function ( as a function of maximum ice extent) .
Ainley, D. G., et al. 1998. Diet and foraging effort of Adelie penguins in relation to pack ice conditions in the southern Ross Sea. Polar Biology. 20 : 311-319.
This paper show how ice conditions affect how well penguins are able to forage and how much of their diet is composed of krill.
Fraser, W.R., Hofmann, E.E. 2003. A predator's perspective on causal links between climate change, physical forcing and ecosystem response. Marine Ecology-Progress Series 265: 1-15.
This paper shows the relationship between sea ice extent and Antarctic krill cohorts. It speculates that ice conditions affected by global warming will change the ice conditions that lead to good krill recruitment.
Belt, M., Deutsch, L., and Jansson, A. 1998. A consensus-based simulatin model for management in the Patagonia coastal zone. Ecological Modeling 110: 79-103.
This paper’s model has a component that models penguin populations and how they are influenced by fish populations.
Reviewer#1: Mike Pennino
Mike commented throughout the proposal. His comments are in blue, mine are in red
[Very constructive and thoughtful comments Mike]
Reviewer#2 : Paul Park
This model may have interesting dynamics due to the contradictory fact that Adelie penguins breed more when they have more breeding room (when more of the ice melts)--even though the krill food populations have declined. However, overall it appears that the affect of melting of ice is a decline in population of both penguins and krill. The relationship between penguins and krill under “stable” ice conditions clearly seems to fit the Lotka-Volterra formulation well. The relationship between ice melting and decline in penguin and krill populations, however, seems to be simply stimulus and response [yes, excellent point Paul - there is no feedback in this relationship between penguins and sea ice - but what will be very interesting to look at is the effect of this global climate change forcing (sea ice) on the feedback between krill and penguins].
I find the audience of Bio 120 to be appropriate for the model’s objectives, and I find the model to be quite feasible. I think that the bullet points were spelled out fairly completely, and I do not know how the model could be improved. So long as feedback actually occurs as a result of reduced ice cover, I think the model will be great. I am interested in playing with the model and seeing the outcome.
Reviewer#3: Jon Beckhardt
Your project both specifies really well the specific factors that are affecting these populations as well as the purpose that this model will have. By saying that the purpose of it will be to show ENVS 101 students the problems that global warming can have in this area, you have set an even more specific purpose for this model, which will only serve to help you more. For this reason, I would be hesitant about pursuing the any of the objectives that begin with “this model could also predict” or something to that extent. I imagine that this could lead to distracting you from the simpler but powerful model that could be built by just focusing on the primary objective. [Good point that Jon makes about keeping the model focused]
I think that what you have layed out in terms of stocks, flows and converters is good. I would consider going more in depth with your temperature function. Obviously, you want to avoid over-complexity at all costs, but it would be interesting if the model considered that the temperature effects of global warming may be more distinct than just a rise in temperature [?]. For example, perhaps the temperature variations from from season to season, or the extremes of each season become different. Such variation could have a bigger impact on sea ice extent than just a temperature increase would have. The responsibilities and timeline look workable and good. [Jon, in the last paragraph you suggested keeping it simple, and in this one you are suggesting adding a great deal of complexity. I go with your first instinct – keep it simple and focus strictly on annual sea ice rather than on finer scale dynamics or on the direct effects of temperature]
Ashley, Sarah and Allysa:
I think this is a wonderful topic for a heuristic model – very exciting. The writing in your proposal is a bit disorganized and hard do follow in places -- see comments and suggestions in text. Given that you already have a high degree of complexity in the basic dynamics between sea ice, penguins and krill, I suggest that you avoid all other complexity in the model. To some extent, I think your goal should be to lead your audience to discover how complex the effects of changing sea ice can be on interacting populations of organisms.
8.9/10