Week 12: Comparing Geospatial Tools

Exploring Ocean Data with ArcGIS

An olive ridley sea turtle, named Shadow Dancer, with her satellite telemetry device attached. She was the first sea turtle tagged for the Project Migration 2008 nesting season. Image Source: Whalenet.

Olive ridley sea turtles (Lepidochelys olivacea) are named for their olive colored shell or carapace. They look very similar to the closely-related Kemp's ridley sea turtle. Adult olive ridley turtles can weigh up to 110 pounds and are approximately 24 to 30 inches long. Hatchlings, or baby turtles, weigh only a few ounces. It is believed that olive ridleys have lifespans averaging around 50 years in the wild. While olive ridleys are the most abundant sea turtle species in the world, they are currently classified as endangered.

Like other sea turtles, they do not breed until 10 to 15 years of age. At that time, they return to the beaches of their own youth to lay their eggs. They lay hundreds of eggs in each nest. The peak nesting season for olive ridley turtles in the Eastern Pacific is during the months of September and October. These turtles have adapted a nesting strategy of safety in numbers. Typically, they arrive at their nesting sites in large groups. The turtles gather offshore and come ashore as a group to nest, an event called an arribada, which is Spanish for arrival. Often, hundreds of thousands of turtles will nest at the same location and time. While this provides some safety against predators, it also makes the turtles vulnerable to environmental disasters, such as oil spills and predation by humans. No other turtle has been observed nesting in such a synchronous manner as the olive ridley. After females lay their eggs, they return to the sea and continue to forage. Hatchlings migrate to the ocean around 60 days after the eggs are laid.

Download the Compressed File of GeoTiff Images and Data about Ridley Turtles

• Right-click the link below to download the zipped file of data and images.
  RidleyTurtlesAM.zip (Zip Archive 5.7MB May7 10)
• Unzip the file. A folder called RidleyTurtlesAM will be created.
• Move the entire RidleyTurtlesAM folder into the Data folder inside the ArcGIS folder. (Path: c://eyesintheski2/week12/RidleyTurtlesAM)

Launch ArcGIS ArcMap and Add Data Layers

• Launch ArcMap by double-clicking its icon on your desktop or by clicking its icon in the Launch Bar.
• To add a September 2008 Sea Surface Temperature image, click the Add Data button. Navigate to the RidleyTurtlesAM folder. Click once on Sept2008SeaSurf.TIF to select the image. Then click Add.
• Repeat the procedure to add the Sept2008Chlorophyll.TIF image.
• Uncheck the Chlorophyll layer to turn it off and make sure that the 2008 Sea Surface Temperature layer added propertly. Then turn the Chlorophyll layer back on.
• Last, click the Add Data button and navigate to the World folder. Click once on country06.shp to select it. Then click Add.
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1. Click the Add Data button.
   
2. Navigate to the Week12 folder.
   
3. Navigate to the RidleyTurtlesAM folder.
   
4. Click once on Sept2008SeaSurf.TIF to select the image. Then click Add.
   
5. Repeat the procedure to add the Sept2008Chlorophyll.TIF image.
   
6. Both images are now in the project. Turn the Sept2008Chlorophyll.TIF image on and off to compare the Sept2008SeaSurf.TIF image with the Sept2008Chlorophyll.TIF image.
   
7. Click the Add Data button and navigate to the RidleyTurtleAM folder.
   
8. Click once to select cntries07.shp. Then click Add.