Case Study — Underwater Research
Click here to download & print the Transect and Quadrat Surveys Worksheet in Adobe Acrobat format.*

Objectives

  • experiment with two underwater research techniques
  • understand the concepts of diversity and abundance

 

Vocabulary

  • transect
  • quadrat
  • diversity
  • abundance

 

Background

Two of the research methods SFS students at the South Caicos research site use to study the coral reef are the transect, or line survey, and the quadrat, or square survey. The line survey is used to study diversity, or how many different types of animals are on the reef. The square survey is used to study abundance, or how many of each type of animal lives on the reef.

To conduct a transect survey, researchers measure a length of string or rope and lay it down on the area to be studied. Then, they identify, count and record each species that the transect line touches. At the research site, transect lines are laid on the reef, and SFS students use underwater slates to record the types and numbers of corals they identify along the transect line. This information will be used to compare diversity in coral communities at various locations around the island.

To conduct a quadrat survey, researchers construct a square and place it in the study area. For underwater research, the squares are usually made of plastic plumbing tubes and joints, weighted with sand. The researchers then identify, count and record the types and numbers of each species within the square. At the research site, quadrat surveys are used to study the abundance and movement of juvenile conch that were raised on a shell-fish farm, then released to the wild.

 

Materials

  • scissors
  • string
  • poster board
  • yardstick
  • stapler
  • Transect and Quadrat Surveys Worksheet (download*)
  • green, red, and yellow construction paper

 

Activity

  1. If possible, have students work in teams.
  2. Each student or team of students will need the following:
3 green squares 3 red squares 3 yellow squares
3 green circles 3 red circles 3 yellow circles
3 green triangles 3 red triangles 3 yellow triangles
3 green stars 3 red stars 3 yellow stars
  1. Have each student or team measure and cut a three-foot length of string to use for the transect survey.
  2. Have each student or team construct a one-foot square for quadrat survey as follows: Cut four strips of poster board 1.5 inches wide by 15 inches long. Assemble the strips to create a square. Overlap and staple the corners. The inside dimension should be 12" by 12".
  3. Have each student or team scatter their shapes in an area approximately 3' by 3'.
  4. Have students conduct transect and quadrat surveys using the worksheets.
  5. Discuss the results.

 

* If you do not have Adobe Acrobat Reader, download it for free from www.adobe.com