Coral reef
onthebeat
Coralphotoquadrats.pdf
Corals and Climate Change
Photoquadrats on a Transect: Student Guide
When scientists want to learn about the health of a coral reef, they have to collect data on the plants and animals found on a reef. One way to do this in by taking pictures of a specifi c area of the reef, called a photoquadrat, at several places along a line, called a transect. Scientists examine the pictures to identify the plant or animal species, record this information, and interpret their fi ndings to estimate the overall health of the reef. In this exercise, you will use the photoquadrat technique to learn about the health of a Hawaiian coral reef.
Step 1: Identify the Species Each photoquadrat photo contains an overlying grid of dots. First, identify the coral, algae or invertebrate under each dot. Use the Coral Reef Identifi cation Guide (Appendix 2) to identify each type of organism.
Step 2: Record the Species After identifying what type of organism is under each dot, put a check mark in the “Times Observed” column on your data sheet each time you observe an organism under a dot. Next, add up all of your check marks for each type of organism and record this number in the “Total Times Observed” column of your data sheet.
Step 3: Calculate Percent Cover Calculate the percent cover for each species. Record this on your data sheet in the “Percent Cover” column on your data sheet. Percent cover = (Number of points under which organism is observed) ÷ (Total number of points) × 100
Step 4: Identify Healthy and Unhealthy Points Add up percent live coral cover. Next add up percent cover for all dead coral points (areas with any dead coral, which looks like a rock, or dead coral covered with algae).
Step 5: Analyze the Data After fi lling in the data table for each photoquadrat, compare the photoquadrats along your transect and answer the following questions:
1. What photoquadrat had the highest percent live coral points? ________________________________________________
2. What photoquadrat had the highest percent of percent dead coral points? ______________________________________
Step 6: Graph data 1. Make a data table that displays total live percent cover in each photoquadrat. 2. Next, use the data table to make a bar graph that illustrates live percent cover of each photoquadrat.. Make sure to number
and label the X and Y axes of your graph and include a title.
Step 7: Draw conclusions Answer the following questions: 1. Based on your data is one photoquadrat healthier than all the others? Write 2 or 3 sentences that explain why.
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Corals and Climate Change
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3. What is the average percent live and percent dead coral cover for all of the photoquadrats on the transect?
Average % live: ________________
Average % dead: _______________
4. Based on your data is the overall reef healthy? Write 2 or 3 sentences that explain why or why not.
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Photoquadrats on a Transect: Student Guide
Corals and Climate Change
Photoquadrats on a Transect: Data Sheets
Photoquadrat 1
Species
Times observed (place a check mark in this column every time you observe each species)
Total times ob- served (add up check marks for each species)
Percent cover (percent cover=total times observed÷total dots × 100)
Antler coral
Caulifl ower coral
Lobe coral
Blue soft coral
Turf algae
Encrusting algae
Dead coral
Percent live cover
Percent dead cover
Photoquadrat 2
Species
Times observed (place a check mark in this column every time you observe each species)
Total times ob- served (add up check marks for each species)
Percent cover (percent cover=total times observed÷total dots × 100)
Antler coral
Caulifl ower coral
Lobe coral
Blue soft coral
Turf algae
Encrusting algae
Dead coral
Percent live cover
Percent dead cover
Corals and Climate Change
Photoquadrats on a Transect: Data Sheets
Photoquadrat 3
Species
Times observed (place a check mark in this column every time you observe each species)
Total times ob- served (add up check marks for each species)
Percent cover (percent cover=total times observed÷total dots × 100)
Antler coral
Caulifl ower coral
Lobe coral
Blue soft coral
Turf algae
Encrusting algae
Dead coral
Percent live cover
Percent dead cover
Photoquadrat 4
Species
Times observed (place a check mark in this column every time you observe each species)
Total times ob- served (add up check marks for each species)
Percent cover (percent cover=total times observed÷total dots × 100)
Antler coral
Caulifl ower coral
Lobe coral
Blue soft coral
Turf algae
Encrusting algae
Dead coral
Percent live cover
Percent dead cover
Corals and Climate Change
Photoquadrats on a Transect: Appendix 1 Photoquadrat Images
Photoquadrat 1
Corals and Climate Change
Photoquadrats on a Transect: Appendix 1 Photoquadrat Images
Photoquadrat 2
Corals and Climate Change
Photoquadrats on a Transect: Appendix 1 Photoquadrat Images
Photoquadrat 3
Corals and Climate Change
Photoquadrats on a Transect: Appendix 1 Photoquadrat Images
Photoquadrat 4
Corals and Climate Change
Photoquadrats on a Transect: Appendix 2 Organism Identifi cation Guide
Corals
ANTLER CORAL - a branching live stony coral. Photo: NPS
LOBE CORAL - a bumpy looking live stony coral. Photo: NPS
BLUE SOFT CORAL - a coral that does not make a calcium carbonate skeleton. Photo: IAN/UMCES
CAULIFLOWER CORAL - a live stony coral with elaborate bends. Photo: IAN/UMCES
DEAD CORAL - rocky substrate with no liv- ing coral polyps. Photo: NPS
Corals and Climate Change
Photoquadrats on a Transect: Appendix 2 Organism Identifi cation Guide
Invertebrates
SEA URCHIN - can have short or long spines and attach to hard substrate. Photo: NOAA
Algae
TURF ALGAE - short fi lamentous algae that may grow on live coral, dead coral, or other substrates. Photo: NOAA
ENCRUSTING ALGAE - pink to dark burgandy algae crust that grows on hard sub- strates. Photo: NOAA
