Using Data to Identify Hot Spots and Predict Bleaching Events


Bleached coral. Image courtesy of NASA.

Coral bleaching is a major concern for reefs all over the world. Under certain environmental stresses zooxanthellae algae will vacate their coral hosts. Without the zooxanthellae, corals lose their colors and appear pale or white, hence the name coral bleaching. Zooxanthellae are also coral's primary source of food and play a key role in helping coral polyps build skeletal reef material. Bleaching can be caused by a number of different stresses including changes in ocean chemistry (particularly salinity or acidification), increased sedimentation in the water, high levels of solar irradiance, or pathogen infections. However, the primary cause of bleaching events is believed to be higher than normal sea surface temperatures. During this lab, you will explore some of the tools used by scientists to identify areas around the world where corals are at risk for bleaching. You will also learn about what bleaching means for the long-term health of coral reefs, and invent a way to model what happens in coral polyps during the process of coral bleaching.

After completing this investigation, you should be able to:

  • explain how maps of bleaching hot spots and degree-heating weeks help identify reefs at risk for bleaching;
  • describe the consequences of coral reef bleaching; and
  • model the process of coral bleaching in coral polyps.

Keeping Track of What You Learn

Throughout these labs, you will find two kinds of questions.
  • Checking In questions are intended to keep you engaged and focused on key concepts and to allow you to periodically check if the material is making sense. These questions are often accompanied by hints or answers to let you know if you are on the right track.
  • Stop and Think questions are intended to help your teacher assess your understanding of the key concepts and skills you should be learning from the lab activities and readings.
Your teacher will let you know which answers you should record and turn in.