The activities are as follows:
- Teacher Guide
- Student activity, Graph Type A, Level 1
- Student activity, Graph Type B, Level 1
- Student activity, Graph Type C, Level 1
- Grading Rubric
Imagine you are snorkeling on a coral reef! You see a lot of plants and animals living together. Some animals, such as sharks, are predators and eat other animals. Other animals, like anemones and the fish that live in them, are mutualists and protect each other from predators. There are also herbivores, such as urchins, on the reef that eat plants and algae. All of these species, and many more, need the coral reef to survive.
Corals are animals that build coral reefs. When you look at a coral you may see what looks like one large rock. In fact, corals are made up of thousands of tiny animals, called polyps. Coral polyps are white but look brown and green because microscopic plant-like organisms, called zooxanthellae (a kind of algae), live inside them. Corals provide the microscopic algae a safe home, and in return the corals are able to feed on the excess sugars the algae produce from photosynthesis. But sadly, corals around the world are dying. Scientists are determined to figure out ways to save coral reef ecosystems by helping corals survive so they can continue to build important and diverse reef habitats.
Corals are habitat specialists and only like to live in certain places. However, the corals compete with other types of algae, like seaweed, for space to grow. Sarah is a marine biologist who is interested in corals because they are such important animals on the reef. She wanted to understand how to help the dying corals. She thought that when herbivores are present and are eating algae on the reef, the corals in turn have less competition for space and thus more room to grow.
Sarah set up an experiment where she put tiles in bins out on the reef. Tiles provided space for animals to grow, including corals. Sarah also put sea urchins in half of the bins. Sea urchins are important herbivores and one of the species that like to eat algae. The other half of the bins had no urchins so the algae would be free to grow there. She had 4 bins with urchins and 4 bins with no urchins. After a few months, Sarah counted how many corals were growing on tiles. She counted corals found in the bins with and without sea urchins. Because sea urchins eat algae, they should free up space for coral to grow. Sarah expected that more corals would grow on the tiles in sea urchin bins compared to the bins with no sea urchins.
Featured scientist: Sarah W. Davies from University of Texas at Austin
The lab webpage can be found here. There is one scientific paper associated with the research in this Data Nugget. The citation and PDF of the paper is below.
Davies SW, MV Matz, PD Vize (2013) Ecological Complexity of Coral Recruitment Processes: Effects of Invertebrate Herbivores on Coral Recruitment and Growth Depends Upon Substratum Properties and Coral Species. PLOS ONE 8(9):e72830
After students have completed the Data Nugget, you can have them discuss the management implications of this research. Watch the news story below and have students consider how urchins can be used as a management tool to help restore coral reefs!