Hawai'i Coral Reef Network


Written by Brian N. Tissot
Kalakaua Marine Education Center
University of Hawai’i at Hilo Hilo


Volunteers from Save Our Seas survey a reef near Heana Beach, Kauai

A. Survey design: be able to address the following basic questions

1. State the problem or hypothesis you are addressing:

  • Descriptive survey: species diversity and abundances;
  • Baseline survey: a reference for future comparisons;
  • Impact study: detect changes due to a specific cause (requires a control site).
  • Criteria for a control site: ecologically similar in every way to the impact site except for the absence of the potential impact

2. Select a site to sample that fits your criteria for the study (the study site).

3. Decide where to sample at your site (the study area): consider reef zonation (reef flat, main reef, reef slope) in relation to the objectives of study.

4. Position a transect in the study area and use a random number table to collect random samples (total number of samples = sample size).

  • A fundamental assumption of statistics is random sampling: the faithful representation of the population in the sample; samples are unbiased and typical of the population.

5. Use the appropriate method for sampling different reef organisms:

  • Corals and seaweeds: estimate percent cover using the line-intersect method with quadrats;
  • Large, mobile invertebrates: estimate density by counting in a quadrat;
  • Fishes: estimate density by counting along a strip transect.

6. Repeat sampling for baseline and impact studies at regular intervals. Sample the same area and use consistent methods between surveys. Rule of thumb:

  • Corals and seaweeds: once or twice a year
  • Large, mobile invertebrates: four times a year
  • Fishes: six times a year

B. Survey execution: minimize errors during surveys:

1. Write clearly and legibly.

2. Review data sheet during survey and make sure it is complete and you can read it.

3. If several people are involved standardize how the data are taken (requires training).

C. Data management: considerations after the survey

1. Have a data manager. Assign one person to collect and hold the data.

2. Review data sheet after survey and make sure it is complete and that you can read it! (all header information must be filled out!!!).

3. Always make copies of data after field work. Keep in different locations.

4. Enter data into a database on a computer maintained in a consistent format (e.g., Microsoft Access).

5. Verify database. Print out data and compare to raw data.

6. Make back-up copies of computer data files; leave copies in several different locations.

D. Data analysis: interpretation of the results

1. Summarize the data using means and standard errors for each combination of species, study area, and survey.

2. Use graphs to display trends in means and standard errors in space and time.

3. Test hypotheses using statistical methods appropriate for the data (e.g., t-tests, analysis of variance, non-parametric statistics).

4. Write a report which summarizes the results and biologically interprets the trends discovered and hypotheses tested.

5. Do something with what you’ve found: give a talk to your local community or school, publish it in a newsletter or professional journal, post it on the Internet.

6. Above all have fun and enjoy the reef!

For more information on Monitoring see the USGS Monitoring Program


Last update: 1/25/2005