Takata-Glushkoff
The top of your coral reef aquarium is the ocean surface, and the bottom of the box is the sea floor. The items within the box are our corals!
Now it’s our turn to be scientists.
What is coral reef topography?
Why should we study coral reef topography?
Volume and Surface Area Formulae
Complete the following procedure, and document your measurements
in the provided data table. Answer all bolded questions along the way.
Note: follow the order of the procedure. Do not try to complete tables before the procedure says to!
1. Collecting Data: Initial Measurements
ü Measure the volume and surface area of each item in your box, using a measuring tape and your above formulae. Record in table 1
ü Measure the volume of the box. Record in table 2
2. Calculating Porosity
Porosity defines the amount of “unoccupied” space, relative to the total volume. In our case, this space is taken by air. In the ocean, that space is taken up by seawater.
Porosity = VvVt
Vv = the void volume
This is the volume of unoccupied space in the box; in other words, the amount of water you would need to fill your aquarium box!
Vt = total volume of box, including occupied and unoccupied space
Record the following in table 2 of your data sheet:
ü Sum all of the object volumes
ü Calculate the void volume
ü Calculate the porosity
ü Convert the porosity fraction to a percentage
3. Discussion: How structure affects species biology and water flow
Now that you have used some of the calculation methods that scientists use, let’s think about their significance. Knowing the porosity, we can think about how the presence of our “corals” might affect how water would flow through it. Notice how different the volumes and surface areas of these different corals are! Different coral structures have varying effects on water flow and species biology.
Q: (small group) Try to imagine water flowing from the side of your box through your “corals.” Differences in structure between corals can affect the water flow differently. Record your thoughts on how the water might move differently around each of your corals, depending on volume and surface area.
Class Q: Why is it important to study water flow?
Class Q: Why do you think the surface area (topography) of corals is important for other living organisms?
4. Create Your Own Species Groups
Remember, the objects in your box are coral.
ü Classify each individual coral into a “coral species” (table 1). Think of a descriptive name for each species type. Fill in the last column of table 1.
You should have multiple individual corals for some of your species. For example, you might block together item types based on shape, size, color, texture, or another characteristic. Choose the characteristic that you think would be most relatable to the way coral species are classified.
Q: Explain what characteristic you are focusing on to decide what species (type) each coral (item) belongs to. Do you think that actual coral species might be classified in a similar way?
5. Estimate Percent Cover
Now, we will practice being biologists. We will estimate the amount of area each species covers in the box. In order to find the percent cover, we simplify the three-dimensional box, and look at it from an aerial view as if it is two-dimensional. It is important that you do not change the facing of your corals in the box at this point. Keeping in mind the area of the opening of the box, estimate the percentage of two-dimensional space in the box that the combined corals of each species occupies. Record in table 3.
Ex: if you have three corals belonging to one species called “smooth cylinders,” you will find the percent cover of those three corals combined.
Q: Why do you think biologists evaluate the percent cover of coral environments?
6. Reflection Discussion
Porosity and percent cover are two different measurements that are used for very different purposes in science. Differences in porosity affect water flow differently. On the other hand, percent cover is used for understanding biological distributions. Ultimately, both measurements are key components to the study of our coral reef ecosystems.
Q: What were some of the difficulties you came across while measuring the volumes? Scientists face these same difficulties! How could a scientist come up with more precise measurements?
Q: What were some of challenges you came across in estimating the percent cover of various species? How could you come up with more precise measurements?
Congratulations! You are a coral reef scientist! Coral reef researchers use the same measurements we practiced using today. These measurements help them improve their understanding of the physics and biology of coral reef ecosystems. By better understanding coral reefs, humans can preserve them more effectively.
Data
Table 1
Item Name (Coral) / Item General Shape / Item Volume / Item Surface Area / Item Type (Species)Table 2
Total Volume (box) / Sum of Item Volumes / Void Volume / Porosity fractionVvVt / Porosity percentage
Eg: 100,000 cm3 / 30,000 cm3 / 70,000 cm3 / 710 / 70%
Table 3
Item Type / Estimated Percent Cover