In this assignment, students will learn about the definition of an ecosystem and ecology - the study of how non-living and living organisms interact within a defined area, and concepts of energy transfer and trophic structure in ecosystems. Short, narrated video stories/lessons and specific examples from South Florida are used to illustrate these concepts.
This activity fulfills the following objectives:
CLO 2: Outline and describe the nature and flow and matter and energy through ecosystem
MLO 2.3 Differentiate among forms of energy and identify how energy and matter flows through ecosystems (MLO3) MLO 2.4 Distinguish photosynthesis, cellular respiration, and chemosynthesis, and identify their importance to living things (MLO4)
MLO 2.5 Define ecosystems and discuss how living and nonliving entities interact in ecosystem-level ecology (MLO5)
For all but a few ecosystems, the Sun is the initial source of energy in a biological system. Algae and plants harness some of that energy through photosynthesis and use it to produce energy-rich organic matter from simple chemicals like water and carbon dioxide. This process is called “primary production” or “autotrophy.” Therefore, algae and plants are also known as autotrophs or “primary producers”. Some of the organic matter that a plant produces builds up to form the plant’s growth and offspring, but a lot of it is “burned” to fuel the plant’s metabolism; the chemical reactions that maintain its life. The remaining biomass is called net primary production.
Animals that eat plants are called herbivores or “primary consumers.” Instead of getting their energy directly from the sun, they get their energy by consuming and digesting organic matter in a process called heterotrophy. Like plants, herbivores have to burn most of the organic matter they consume, but as long as they’re getting enough to eat they can use the excess organic matter to grow and reproduce.
Animals that eat herbivores are called carnivores and are also known as predators or “secondary consumers” because they consume other consumers to get their energy and organic matter. Like the levels below them, secondary consumers have to burn most of their organic matter to keep themselves alive, but can use what’s left over to grow and reproduce creating secondary production – the organic matter biomass result of heterotrophy.
Like consumers, decomposers are heterotrophs. They get their energy by breaking down dead organisms and waste. Decomposers can be considered a “terminal trophic level,” because they use up the last of the organic matter left over from the other trophic levels. The most common decomposers are bacteria and fungi. When something is fully decomposed, its organic matter has all been broken back down into simple molecules like water and carbon dioxide.
Each level of production or consumption is called a trophic level. There is no definite limit to the number of trophic levels that can exist in the environment. For example, small predators can be eaten by bigger predators, which can be eaten by even bigger predators, and so on. However, at each higher level there’s less energy and matter available until at some point there’s just not enough to support a population of bigger predators.
[Image unavailable: A terrestrial food chain showing a linear energy transfer relationship between organisms. Plants gather sun's energy and store it as biomass, which transfers to a grasshopper herbivore, which is eaten by a secondary consumer carnivore chipmunk, which is eventually consumed by a top predator hawk. Note the loss of energy as heat and the contribution of detritus from all levels. Matter, shown as chemical nutrient cycling, is recycled back to the soil and used as nutrients for plants.]
Figure 1: A terrestrial food chain showing a linear energy transfer relationship between organisms. Plants gather sun's energy and store it as biomass, which transfers to a grasshopper herbivore, which is eaten by a secondary consumer carnivore chipmunk, which is eventually consumed by a top predator hawk. Note the loss of energy as heat and the contribution of detritus from all levels. Matter, shown as chemical nutrient cycling, is recycled back to the soil and used as nutrients for plants.
A food chain is a simple visual representation of energy and matter flow from one trophic level to the next through an ecosystem. By tracing the flow in a system, scientists can determine the role of each organism and tabulate the loss of matter and energy from each trophic level. Food chains are almost always an oversimplification of the natural food web, which is highly complex. In the real world there are many pathways that interconnect and food webs help visualize these more complex relationships. Occasionally one or more individuals may be removed from a system due to human interaction or other disturbance resulting in changes in the transfer of energy and matter throughout the food web – a trophic cascade. While not without its faults, using the food chain simplification allows scientists to follow matter and energy flow, see how the transfer of matter and energy from one trophic level to the next is not an efficient process, and determine what the impact of removing (or adding) species (invasives) may have on the rest of the ecosystem.
Instructions:
Watch the following video for a review of Ecosystem Ecology or see URL: Links to an external site.
Watch the following video for a review of food webs with an emphasis on aS. Florida Ecosystem or see URL:
Part 1: Construct a Food Web. In this activity you will be assigned a specific ecosystem (alphabetical by last name - see below), where you will construct and draw a representative food web, NOT A FOOD CHAIN, for that ecosystem. You may draw your organisms/food web by hand (I love seeing your nice artwork!), draw a food web using word/or other appropriate software, where images of your organisms can be taken from the web, or a combination of both.
Food Web Ecosystems assigned by LAST NAME: Tropical Rainforest (Starts with A-E), Desert (Starts with F-I), Freshwater lake or pond (Starts with J-M), Arctic Tundra (Starts with N-Q), Coastal Ocean (R-T), Wetlands (U-Z) ( i need to do dessert ).
Your Food Web diagram SHOULD TAKE UP AN ENTIRE 8.5x11 piece of paper and include the following:
- Your food web must have 10 different organisms from your assigned ecosystem. Make sure they are identifiable organisms with a picture/image and correctly spelled names and LARGE FONT/WRITING SIZE
- Clearly label each organism appropriately as: Primary Producer, Consumer (indicate whether its Primary, Secondary, etc), Detritivore/Decomposer, and Top Predator. You must include at least 1 of each of these.
- Arrows indicating the correct direction and transfer of energy
- If drawn on paper, you must take a picture and upload this picture separately as its own file; if drawn using software, upload a separate file of your computerized drawing. Your files must be in a format I can see/open - you will receive a 0 on this section of the assignment if I cant.
Part 2: Download the template foodwebs
and answer the 4 questions within as they relate to your food web and ecosystem.
YOU MUST USE AND SUBMIT THIS TEMPLATE in .docx format for full credit when answering the questions. (Note: if you do not use the appropriate template or format, you will lose points). Your food web will be submitted as a separate document.
Requirements:
- Submit 2 documents: Your Food Web diagram and your completed assignment template: