Module 2: Prey Maps

Healthy populations of species depend on a healthy food source Healthy populations of species depend on a healthy food source. Then why doesn’t the Ocean Tracks interface have tracks or data layers showing where the prey of the Ocean Tracks species are located? Although scientists have an idea of where prey species are, tracks and detailed maps of this kind are not actually available. Many prey species are too tiny to carry tags, so scientists have to use other kinds of clues to figure out where they might be. You’re going to follow these same clues to generate your own map of where elephant seal prey are likely located in the Pacific Ocean. It might be worth pointing out here that most prey species are too small to carry a tag!

In this module, you will: Think about the data that are (or are not) available on the Ocean Tracks interface, and how they can be used to understand where prey species are Take measurements of animal tracks Try to make sense of what the data are telling you Look at the data overlays, and think about the linkages between the data overlays and the animal tracks

Directions Use the prompts outlined here to help you gather the information you need. Use this document as a template to record/document your work. Incorporate screen shots of maps, your observations, measurements, charts/graphs, and the results of your research.

Library Research First, spend some time in the Ocean Tracks library and online researching food webs and the oceanographic data overlays on the Ocean Tracks interface. Your research should focus on the following questions: What is a species? Population? Community? Ecosystem? Food web? What is meant by the term primary production? What overlay on the Ocean Tracks interface shows primary production in the surface of the ocean? What determines how much primary production occurs? What do elephant seals eat? Are they autotrophs, heterotrophs, producers, consumers, herbivores, carnivores, or omnivores? What is the link between primary production and elephant seals? Record your notes on additional slides

Library Research From what you’ve learned, construct a food web that starts with phytoplankton as the producers and the elephant seal as a top level consumer. Label and describe each component of the food web with vocabulary terms such as autotroph, heterotroph, producer, primary, secondary or tertiary consumer, herbivore, and carnivore.

Library Research Next, spend a little time learning about the curviness tool on the Ocean Tracks interface. Try using the curviness tool on a couple of tracks and answer the following questions: What does the curviness tool show? What might this tell you about the animal’s behavior along a section of the animal’s track? Curviness tool: How does it work? The curviness number is calculated by dividing the distance along the path from point A to point B (solid line) by the straight-line distance between point A and point B (dashed line). The closer this number is to 1, the straighter the animal is travelling. The higher the value is, the curvier the animal’s path is.  

Where are the prey of elephant seals likely to be found? Challenge Where are the prey of elephant seals likely to be found? http://tolweb.org/Octopoteuthis_deletron/19843

Data Collection Plan Just like the elephant seals, their prey move around from month to month. To make things simple, we’re just going to focus on developing a prey map for one specific month – August 2005. This is the time during which seals are undertaking their post-molting migrations out to sea to feed.

Data Collection Plan To create a prey map for the elephant seals in August, inspect the tracks of elephant seals #528, #536, #541, and #546. Measure the animal’s speed, depth, and track curviness during the section of track that occurs in August. This will give you some clues about what the animal is doing and where it might be feeding. Record this information in the Ocean Tracks measurement table. Repeat these measurements for the section of track that occurs in July for the same elephant seals: #528, #536, #541, and #546.

Data Collection Paste your measurement table here, and record any observations you have on additional slides. Be sure to include your own comments on what you observe, screen shots, and additional questions you may have.

State a Claim Where do you think the elephant seal is feeding? Mark the feeding locations on your map, and paste a screen shot of the map here.

Provide Evidence What is the average curviness of these elephant seals in July? In August? Average curviness = Sum of curviness values from all 4 seals 4 What is the average speed of these elephant seals in July? In August? What is the average depth of these elephant seals in July? In August?

Provide Evidence What other pieces of evidence do you have that indicate where the seal is feeding?

Explain Your Reasoning How do your speed, curviness, and depth measurements compare between July and August? What does this tell you about the seal’s behavior? Explain how any other evidence you’ve gathered supports your claim.

Data Collection Plan Next, you’re going to inspect the chlorophyll layer in the Ocean Tracks interface. This might also give you some clues about where the elephant seal’s prey is located. Display the chlorophyll layer in August 2005. Paste a map of this layer with the tracks displayed on the next slide.

What do you notice about the chlorophyll in the area where the seals are feeding? Refer back to your notes from the Ocean Tracks library to help you think about this.

State a Claim Now, using the pieces of information you’ve gathered from the seal tracks and the overlay, and any additional information you’ve gathered, create a prey map for the month of August 2005. This map should be drawn on poster paper. Mark the map with the pieces of evidence that helped you decide where prey are located.

Share Your Findings Present your map to the class, explaining your reasoning and why you drew your map the way you did.