Contextualization

Food chains and webs are central concepts in the study of Biology. Both are models used to represent the feeding interactions that occur between living beings in an ecosystem, in other words, who eats whom in a given environment and how energy and organic matter flow from one organism to another.

A food chain is a linear model, where each organism belongs to a trophic level, that is, a position in the chain that indicates who it eats and who eats it. At the base of all food chains are the producers, organisms that can synthetize their own organic matter, followed by the consumers that feed on other living beings, and decomposers that feed on dead organic matter.

A food web, on the other hand, is a more real and complex representation of the feeding interactions in an ecosystem, since an organism generally does not feed on just one type of food, but on several. Thus, in a food web, several organisms are interconnected through multiple food chains.

These concepts are vital to understand the interactions between living beings and how human action can affect them. Pollution, excessive hunting and fishing, the introduction of exotic species and the destruction of habitats are some examples of how humans can alter food chains and webs, causing ecological imbalances and loss of biodiversity. Therefore, understanding how these systems work is the first step towards conservation and environmental sustainability.

The importance of these ecological interactions, however, goes beyond nature preservation. They are also fundamental to human activities such as agriculture, fishing, pest and disease control, in addition to playing a crucial role in ecosystem services such as pollination, biological control, decomposition and nutrient recycling. Without food webs and chains, life as we know it would simply not be possible.

For this project, I suggest that the students consult the following resources:

1. Book: "BIO volume único" by Sonia Lopes and Sergio Rosso, available in digital version on Amazon (https://www.amazon.com.br/Bio-Sonia-Lopes-Sergio-Rosso/dp/B01F9S3S3C)

2. Video "Food Webs and Chains" on the Youtube channel Ciência Todo Dia (https://www.youtube.com/watch?v=-W31ZHJ7G1I)

3. Khan Academy website in Portuguese, with free didactic material on the subject (https://pt.khanacademy.org/science/biology)

Practical Activity - "Restoring the Balance: An Experimental Study on Food Webs and Chains"

Project Objective:

To study the food chains and web of a specific environment and identify the human impacts on these structures, proposing solutions to restore the ecological balance.

Detailed Project Description:

The students will be divided into groups of 3 to 5 members. Each group will choose a specific local ecosystem for interest, such as a park, a natural reserve, a local water body, or even a more urban location such as a public garden. The choice will depend on the accessibility and safety of the location.

Each group must carry out a holistic survey of the chosen ecosystem, identifying the main components of the food chains present (producers, consumers and decomposers) and mapping the food web as much as possible, carrying out bibliographic research to help in this process. This is the multidisciplinary part of the project, since it involves knowledge of both Biology and Geography (understanding of the location and characteristics of the regions).

With the understanding of the established food web, the group must identify and document possible human impacts that are altering this dynamic and propose measures to mitigate these impacts.

The students must document the entire investigation and analysis process, including field observations, drawings, photographs and any other type of data collected. They must use these records to prepare a detailed report on the project, according to the "Project Deliverables" section below.

Necessary Materials:

1. Field notebook
2. Pencils and pens
3. Camera or Smartphone (for photographs)
4. Research material (books, internet access)

Step by Step to Carry Out the Activity:

1. Divide the students into groups of 3-5 members.
2. Each group chooses a local ecosystem for study.
3. Carry out field trips, always safely, to observe and collect data on the chosen ecosystem.
4. Identify the main members of the food chain of that ecosystem (producers, consumers and decomposers).
5. Prepare a diagram representing the food web of the ecosystem.
6. Document the possible human impacts identified.
7. Propose solutions to reduce these impacts.
8. Compile the observations and analysis in a detailed report.

Project Deliverables:

Each group must deliver a complete project report. The report must contain:

1. Introduction: Presentation of the chosen ecosystem and justification for the choice. Importance of this ecosystem and the role it plays in the region. Brief description of the concepts of food chains and webs and their importance to understand the ecological interactions in the chosen ecosystem.

2. Development: Detailed description of the process of identifying the members of the food chain and building the food web. Discussion of the human impacts identified and proposals for solutions. This section should be complemented with photos, drawings, graphs and any other type of evidence collected during the investigation.

3. Conclusion: Discussion of what was learned throughout the project. Discussion on how the activity impacted the group's understanding of the food chain and web and human interaction with these structures. Project evaluation and discussion on how it could be improved in the future.

4. Bibliography: List of all sources consulted throughout the project.

The total duration of the project, including data collection, preparation of the food web, identification of human impacts and writing of the report, should be more than 12 hours per student.