Ecosystem Ecology Activity Questions
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, as well as 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.
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.
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.
Watch these two videos: https://youtu.be/v6ubvEJ3KGM

Instructions: In this activity you will be assigned a specific ecosystem based on the first letter of your LAST NAME. Wetlands (Starts with A-E), Freshwater biome (Starts with F-I), Arctic Tundra (Starts with J-M), Desert (Starts with N-Q), Coral Reef (R-T), Tropical Rainforest (U-Z). For the ecosystem you will need to draw or construct a food web, NOT A FOOD CHAIN. Your food web must have 10 different organisms and include at least 1 of the following: Primary Producers, Consumers, Detritivores/Decomposers and Top Predator. The diagram should take up an entire 8.5 x 11 piece of paper and show: Identifiable organisms with correctly spelled names and large font/writing size.
Arrows indicating transfer of energy.
Clearly labeled organisms as Primary Producers, Consumers, Predators or Decomposers.
You will have to upload the food web. You can make it on a computer or draw it and take a photo to upload. Please look at this website to help show you how to draw a food web. https://www.wikihow.com/Draw-a-Food-Web
**My last name starts with a C so the Food Web should be based on WETLANDS ecosystem**