Biology Project:
Gone Fishing
Step 3: Confirm your choices and Practice Analyzing Data

With your team members, analyze the following data. (Click on the images below for the larger versions.) It was collected at the same time and place, so we can compare the two graphs:

Graph A	Graph B
CTD (Conductivity-Temperature-Depth) sensor: The vertical axis, or Y-axis, of the graph shows the depth the CTD sensor reached as it was towed through the water. The horizontal axis, or X-axis, shows the distance in kilometers that the boat traveled collecting data on that day. The black line in the image shows the bottom of the ocean.	Fluorometer sensor (floor-ah-met-ter): The color scale to the right shows the amount of chlorophyll in the water measured as units of fluorometry. Phytoplankton use chlorophyll in their cells for photosynthesis, so the greater the amount of chlorophyll in the water, the greater the number of phytoplankton.

In your notebook answer the following questions:

1. In graph A, how far did the research vessel travel? ___km in the temperature graph
   
2. To the right of graph A you will see a temperature scale that relates the color of the water to the water temperature. Describe how the temperature of the water changes as the depth changes. Can you find the place where the warm water and cold water meet (and where the temperature changes quickly)? This is the thermocline. What is the depth range where the thermocline is located?
   
3. In graph B, at what average depth do you find the highest concentrations or levels of chlorophyll?
   
4. Look again carefully at the temperature graph A, and then at the fluorometry graph B What can you conclude about the relationship between the thermocline and the amount of phytoplankton? Why? (Hint: Don’t forget about the importance of light and nutrients to phytoplankton!)

Check out the Control Room (under C.o.o.l. Tools at the top left of the page) to learn more about CTDs, Fluorometers and thermoclines!