Penn State NASA

Lab 7: Reef Ecology


Lab 7: Reef Ecology

The goal of this lab is to:

  • observe and compare the health of reef by exploring different parts of the ocean.


First, you will be watching videos from the Catlin Seaview Survey as well as photos to learn how to determine the health of reefs. Then you will be looking at before and after photos of reef bleaching events. Finally, you will be looking at the risk to reefs in the future.

Please Note: There is practice only for the video part of the lab. There are not enough pre and post photographs of bleaching events to use some for the practice, but the questions are going to be fairly straightforward, so practice is not necessary.

Please watch the videos below. To move around, insert your cursor in the videos to manipulate the camera and stop on particular items of interest or to change direction. The best way to move the camera is with your keyboard arrows (up, down and side to side).

The goal of this part of the lab is for you to show you can identify different types of coral as well as overall health of the reef at different locations. Make sure you have read the material on reefs in the module before attempting to complete the lab. Below are the different types of coral for you to identify. In addition, we show pictures of algae that colonize reefs as well as reef damage from storms. Healthy corals show a variety of colors from the different algal symbionts. Unhealthy corals show fewer colors, more algal colonization, more breakage and often are bleached white. Remember, algae are some of the key markers of an unhealthy reef.

Photographs of different types of coral

Photographs of algal colonization

The following images show some of the range of morphologies and colors of colonizing algae

Photographs of reef damage from storms or people

Files to Download





Prep and Instructions

Load the ReefsAllFin.kmz file. The locations of reefs of interest are shown with flags. The videos are shown with diver markers, the still photographs are shown with wave markers. The videos run best if you open them a browser such as Firefox (see Google Earth window top right).  Before submitting your lab, let’s begin with the practice. Make sure you do this part of the lab to get comfortable with the tasks you will be asked to do and to receive feedback about your answers. Watch the videos at the following locations and answer the questions below. Make sure you maneuver up and (especially) down as well as side-to-side.

Practice Questions

Part A

In this section, you will be looking at the health of reefs using their color, the presence and abundance of algal overgrowth and the and the presence of bleaching. Go to the Belize reef. Look around the reef and answer the following questions.

  1. Is there living coral? (look for different colored coral) (Yes/No)
  2. Is there brain coral? (Yes/No)
  3. Which types of coral do you see?
    A. Table bottom
    B. Table bottom and staghorn
    C. Staghorn and brain
    D. Table bottom, staghorn, and brain
  4. Is there any bleached coral? (Yes/No)
  5. Is there any algal overgrowth? (Yes/No)
  6. How would you describe the health of the reef?
    A. Very healthy
    B. Moderately healthy
    C. Not healthy

Part B

In this part of the lab, you will compare photographs from before and after major events that have impacted reefs. Answer the questions about the changes in the abundance of different types of coral, algal overgrowth, or percent bleaching.

Go to Lizard Island. Please look at the two pictures and answer the following questions.

  1. Which picture has the healthiest reef? (upper/lower)
  2. What is most diagnostic of the health of the upper photograph?
    A. The healthy reef has very tall coral
    B. The healthy reef has a lot of different colors
    C. The healthy reef has bleached corals
  3. What is most diagnostic of the health of the lower photograph?
    A. The unhealthy reef is bleached
    B. The unhealthy reef is growing quickly
    C. The unhealthy reef is covered by algae

Part C

In this section, you will be looking at the projected health of the reef in the future. Load the three Reef risk kmz files, the first is for today (ReefsAtRiskRevisitedPresent.kmz), the second for 2030 (ReefsAtRiskRevisited2030.kmz), and the third for 2050 (ReefsAtRiskRevisited2050.kmz). When you look at these, make sure you only have one set of projections and keep the others switched off. Look at the Indian Ocean and answer the following questions.

  1. Where is the threat highest at the current day? Select all that apply.
    A. Indonesia
    B. East Africa
    C. Maldives
  2. Given the distribution of the threats in 2030 compared to high population areas around the margins of the ocean and the lower population areas in the ocean islands, which is most likely the largest threat to reefs? Select all that apply.
    A. Bleaching
    B. Ocean acidification
    C. Pollution and overfishing
  3. Why is the threat is so high everywhere in 2050? Select all that apply.
    A. Ocean acidification
    B. Bleaching
    C. Pollution and overfishing