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CRAMP Rapid Assessment Techniques (RAT)

The CRAMP Assessment Technique (RAT) is a highly abbreviated version of the CRAMP monitoring protocol, consisting of a single fish transect, a single benthic transect, a rugosity measurement, a sediment sample and various qualitative habitat observations. The assessment protocol is designed to produce quantitative spatial data that is consistent with and comparable to data taken at the permanent monitoring sites. The power of the RAT lies in large numbers of replicates taken over the spatial range of a given habitat. The assessment program expands our ability to describe habitats and spatial distributions of Hawaiian reef organisms in relation to various environmental factors. However, the assessment protocol requires a small fraction of the human effort and cost per site. This is critical due to the large number of sites needed to describe habitats along the entire coast of Hawai‘i. Considerable time saving is achieved because no permanent transect markers are needed and no permanent photo-quadrats are installed. Assessment data can be used with monitoring data for spatial comparisons, but the benthic assessment data does not have the statistical power needed to establish temporal change with the degree of precision involved in the monitoring effort unless an extremely large number of RATs are performed in a small area or repeatedly over time.

All of the CRAMP long-term monitoring sites have been established on hard bottom in coral habitats stratified at depths of 3 m and 10 m. In contrast, the RAT is used in all coral reef ecosystem habitats and at all depths being mapped.

The reef fish sampling method used in the RAT is identical to the monitoring method, but only one 25m x 5 m transect is measured as compared to 4 transects for monitoring. The benthic sampling effort is the same as used at the monitoring sites, but reduced from ten 10 m transects to a single 10 m transect that only has sufficient power to describe habitat differences. The RAT requires the use of two divers to conduct the full survey (fish, benthic digital still images, rugosity measurement, sediment and observations) in a single short dive. In contrast, establishing the monitoring sites took a team of 6 divers multiple dives to install and conduct the initial monitoring of the site. Data entry time for the assessment method is reduced to less than 2 person-hours per site for the assessment method compared to more than 20 person-hours for the monitoring sites. The monitoring site protocol must have sufficient statistical power to detect a less than 10% change in coral cover between samplings. The assessment protocol only requires sufficient statistical power to allow quantitative description of a given habitat. Generally from 3 to 7 RATs are needed to describe a given habitat depending on its heterogeneity.

  1. Location of the assessment site is pre-determined using the habitat maps and other information to develop the experimental design. A stratified random sample is selected from within each habitat. Latitude and longitude are determined for each rapid assessment site and entered as waypoints into the GPS.

  2. A field team consisting of 2 divers navigates to a randomly selected waypoint using GPS, marks the location with a lead weight and float and accurately establishes the location using GPS measurements. Divers descend together. Diver 1 carries one 25 m transect line. Diver 1 begins fish transect starting at the marked waypoint and moves along the depth contour. The fish count method is identical to that described above for the monitoring method. Diver 2 carries a digital camera system and rugosity chain. As diver 1 lays out the transect line, diver 2 takes still images along the first 10 m, leaving enough space between divers as not to affect fish populations. Diver 2 also runs rugosity on the 10-m transect. Diver 1 completes the fish transect and collects sediment and records general observations while compiling a species list. This produces a data set similar to the monitoring sites but with only one fish transect.

  3. Data entry takes about half an hour for the fish data, less than needed for fish data taken at the monitoring sites. The major time saving is on the benthic sampling data. No permanent photo-quadrats are involved. Only one transect is sampled with PhotoGrid. The entire procedure will require less than 3 hours of analysis time per transect.

 

Last Update: 05/02/2008

By: Lea Hollingsworth

Hawai‘i Coral Reef Assessment & Monitoring Program

Hawai‘i Institute of Marine Biology

P.O. Box 1346

Kāne‘ohe, HI 96744

808-236-7440 phone

808-236-7443 fax

email: jokiel@hawaii.edu