Name:________________________________ Date: Per:

Mesocosm Discussion

AIM: Setting up sealed mesocosms to try to establish sustainability (Practical 5).

Essential ideas:

The continued survival of living organisms including humans depends on sustainable communities.
Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.
Continued availability of carbon in ecosystems depends on carbon cycling.

Introduction

Mesocosms are small experimental areas that are set up as ecological experiments. Fenced-off enclosures in grassland or forests could be used as terrestrial mesocosms; tanks set up in the laboratory can be used as aquatic mesocosms. Ecological experiments can be done in replicate mesocosms, to find out the effects of varying one or more conditions. For example, tanks could be set up with and without fish, to investigate the effects of fish on aquatic ecosystems.

In this inquiry you will be setting up a sealed mesocosm to test what type of ecosystems are sustainable. This involves sealing up a community of organisms together with air, soil, and/or water inside a container. You will be observing your mesocosm for 4 weeks. (You have the option to observe it for longer)

Here are some questions before setting up either aquatic or terrestrial mesocosms.

What types of containers will you use? Large glass jars are ideal but transparent plastic containers could be used.
Should the sides of the container be transparent or opaque?
Which of these groups of organisms must be included to make up a sustainable community: autotrophs, consumers, saprotrophs and detritivores?
How can we ensure that oxygen supply is sufficient for all the organisms in the mesocosm as once it is sealed?
How can we ensure the proper levels of moisture and nutrients?
How can we prevent any organisms suffering as a result of being placed in the mesocosm?

Here is a great source for mesocosm ideas: http://www.magzinr.com/user/D_Faure/mesocosm

Here are some components you should consider while planning your mesocosm:

Soil – The productivity of soil depends on mineral content, drainage, water-holding capacity, air spaces, biota (animals present e.g. earthworms) and the potential to hold organic matter.

Seeds/plants – As you have limited growing space, your plants will need to be small. There will be a limited selection of seeds from the lab, or you can see what is available to purchase.

Organic matter – A mix of leaves, grass, and easily decomposed food such as fruit (do not include citrus fruit or peelings) could be used but you should think carefully about what proportion of each of these components you should use.

Insects – Insects such as fruit flies can help decompose the detritus.

Water – Tap water may be treated with chemicals and so should not be used in the aquatic chamber. What would be a good source of water?

Substrate – You should put gravel or sand at the bottom of this chamber. Organisms you put in this chamber may need this substrate as part of their life cycle, or as a refuge.

Organisms –snails and fish could be used in your mesocosm but you should be careful to select the fish carefully, and limit the number of larger organisms in this chamber. Add only the number of consumers you think that the chamber will support.

Brainstorm: What is an ecosystem? Why do scientists study ecosystems? What is a mesocosm? How do mesocosms help scientists study ecosystems?

Day 1:

To get a better understanding of how scientists study ecosystems, you will be working in lab groups to brainstorm an Investigative Question, generate a hypothesis, and come up with a preliminary design for your mesocosm. Please use the resources provided to learn more about mesocosm and their significance.

Research Question: You will be designing and creating a sealed mesocosm in order to determine what types of conditions are necessary for establishing sustainability in a closed system. This involves sealing up a community of organisms together with air/soil and/or water inside a container. You will be observing and taking measurements of your mesocosm.

How does __________________ affect _________________ found in ___________?

(IV) (DV)

Background Information:

Provide some information about your investigation and the reasons you are undertaking it. (Resources: Mesocosm Experiments as Tools for Ecological Climate Change Research, Mesocosm Link, 4.1 Video / Oxford Biology Book). Consider addressing the following questions in your background:

What is a mesocosm?
How are mesocosms useful to scientific climate change research?
How does a mesocosm establish sustainability? What ecological concepts are important to sustainability?

________________________________________________________________________________________

Preliminary Design:

You and your group mates will create a plan that details the conditions you think are necessary for establishing sustainability in a sealed mesocosm. DO OUTSIDE RESEARCH and make sure to address the following questions in your plan:

What type of container(s) will you use and why? Large glass jars are ideal but transparent plastic containers could be used. Should the sides of the container be transparent or opaque?
What substrate will you use in your mesocosm? Why did you select this particular substrate?
Which groups of organisms must be included to make up a sustainable community: autotrophs, consumers, saprotrophs and/or detritivores? What will groups of organisms will you include and why? (Hint- think about their requirements and the role they will play in your mesocosm. Can the requirements of all organisms be met once the mesocosm is sealed?)
How can we ensure that the oxygen supply is sufficient for all organisms in the mesocosm once it is sealed? How can we ensure proper levels of moisture and nutrients?
What other factors did you try to plan for? How will you deal with these?
How can prevent any organisms suffering as a result of being placed in the mesocosm? How will you follow the IB Animal Experimentation policy?

________________________________________________________________________________________

Day 2:

On the second day, you will build your mesocosm based on your preliminary design. We will also spend time going over lab report expectations for IB Biology. You will not be writing a formal lab report for this lab, instead you will be focusing on just the Exploration section of a formal lab report - personal connection, background, investigative research question, hypothesis, variables, materials, experimental setup, procedure, and safety. There will be a few examples for you to reference. Please use the IA Lab Report Template below to guide your work as well as the rubric for assessment.

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IA Lab Report Template

TITLE (The effect of IV on DV)

Personal Connection

2-3 sentences explaining your interest in the chosen topic and how specifically you have made this investigation uniquely your own -applicable for the IA. You earn marks for making a personal connection, making a global connection, and having a unique experimental design.

Exploration

Background

This is the place to summarize what you have verified about the topic using research. Please make sure your background addresses the following questions: How does your investigation connect to the scientific topic covered in the IB Biology syllabus? What is the science behind your experiment? How does the science influence the methodology designed? Use reputable online sources, but you can probably start with your textbook and notes from class. You should have a minimum of two sources cited at the end of your report (No Wikipedia). Use MLA format for in text citations and for your works cited. You may repeat some of this information in your conclusion when comparing your results to literature values and when explaining your results. When you proofread this section, make a list (actual or mental) of the scientific facts used. If there are none, you need to rewrite. (2-3 paragraphs)

Investigative/Research Question – must be focused and not ambiguous in any way. Restating the question posed to you is not sufficient. Your question should be more focused than the question I posed to you. Should sound something like: "What is the effect of IV on DV?" Be specific about levels of independent variable used and how the dependent variable will be measures.

Hypothesis – state first & then give a logical rationale – your conclusion should address the hypothesis you are giving here. Information in your background section should be repeated and used to support your hypothesis. Do not assume that the reader can tell which parts of your background research support your hypothesis. State the science behind your hypothesis explicitly and offer citations.

Variables – chart or list identifying Independent, Dependent & Controlled Variables. Include in this chart how dependent variables will be measured, and how & why controlled variables will be controlled. Make sure you answer the following question: How will not controlling for a specific variable affect your data? For example, if you are assuming that temperature will be controlled by the air handling system for the building, state that. Elaborate around how your data could be affected if temperature wasn’t controlled for. Dependent variables should be measured quantities, not calculated quantities. If you are planning on calculating density, mass or volume is the Dependent variable, not density. A rate of increase (slope) is also a derived variable. Please specifically define your treatment groups, include units, and uncertainty. For example, if your independent variable is the size of an agar cube, you should clearly identify which sizes you will be using in your research.

Materials – make a table listing precisely what materials you are using and what you will use it for. 250 mL beaker not beaker, electronic balance not balance, 100 mL graduated cylinder not graduated cylinder. For any chemicals used, identify the compounds precisely including concentrations where appropriate. Any measuring device will have a range of uncertainty associated with the measurements of it, please explicitly state the absolute uncertainty associated with your measurement tools underneath your materials.

Experimental Setup – annotated photograph showing how variables were instituted, especially the controlled variables. This is not just a variety of equipment sitting next to each other. Can be a drawing if necessary.

Procedure – write numbered list of steps that can stand alone and be followed by any member of the junior class. Be sure to include details of data collection. Saying you will "collect data" is not sufficient, under any circumstances. If you're measuring length, say you will measure the length with a ruler, not just measure the results. Include multiple trials in your procedure!!! Five is generally a good goal. Even if you are sure you will run out of time to do 5 trials, put at least 5 trials in your procedure (10 minimum if you use a T-test)!! Don’t exaggerate the number of trials you plan on doing either. If the procedure is simple enough to do 100 trials, say you will do 100 trials, but don’t say that unless you know there is enough time. State the method of data analysis as last step.

Safety - Include any appropriate safety precautions, including the use of goggles and aprons (if appropriate).

--------------------------------------------------------------------------------------------------------------------------------------------------Exploration Rubric:

This criterion assesses the extent to which the student establishes the scientific context for the work, states a clear and focused research question and uses concepts and techniques appropriate for the Diploma Program level. Where appropriate, this criterion also assesses awareness of safety, environmental, and ethical considerations.

IB Mark	CHS Mark	Descriptor
5-6	Exceeds (6-7)	The topic of the investigation is identified and a relevant and fully focused research question is clearly described. The background information provided for the investigation is entirely appropriate and relevant and enhances the understanding of the context of the investigation. The methodology of the investigation is highly appropriate to address the research question because it takes into consideration all, or nearly all, of the significant factors that may influence the relevance, reliability and sufficiency of the collected data. The report shows evidence of full awareness of the significant safety, ethical or environmental issues that are relevant to the methodology of the investigation.
3-4	Meets (4-5)	The topic of the investigation is identified and a relevant but not fully focused research question is described The background information provided for the investigation is mainly appropriate and relevant and aids the understanding of the context of the investigation The methodology of the investigation is mainly appropriate to address the research question but has limitations since it takes into consideration only some of the significant factors that may influence the relevance, reliability and sufficiency of the collected data The report shows evidence of some awareness of the significant safety, ethical or environmental issues that are relevant to the methodology of the investigation*
1-2	Nearly Meets (2-3)	The topic of the investigation is identified and a research question of some relevance is stated but it is not focused The background information provided for the investigation is superficial or of limited relevance and does not aid the understanding of the context of the investigation The methodology of the investigation is only appropriate to address the research question to a very limited extent since it takes into consideration a few of the significant factors that may influence the relevance, reliability and sufficiency of the collected data The report shows evidence of limited awareness of the significant safety, ethical or environmental issues that are relevant to the methodology of the investigation.
0	Beginning (1)	The student’s report does not reach a standard described by the descriptors above.

Name:________________________________________ Date:______________ Per:______