CRAMP Benthic Monitoring
The requirements of the CRAMP experimental design for observer-independent accuracy, reproducibility, quality control and archiving led to the abandonment of the classic method of using a 1 m square quadrat frame and an underwater writing slate to estimate benthic coverage. New methodology has been designed for both monitoring and assessment. This section describes the monitoring design in detail. The Assessment design is an abbreviated version of the monitoring design and is described under Rapid Assessment Technique.
Paul Jokiel shown running classic benthic quadrat method at Molokini Island in Oct. 1998. Photo by Eric Brown. (Click image for larger view.)
The classic monitoring method of taking data underwater using a quadrat frame had been used in Hawai‘i for over 30 years, but failed to yield reproducible results under the conditions set by the CRAMP experimental monitoring design. A detailed analysis of methodology that led to the adoption of the CRAMP monitoring design is described in Brown et al. (2004).
Skippy Hau of the Hawai‘i State Department of Aquatic Resources sets 10 m transect lines along the 100 m spine transect line at Hakioawa, Kaho‘olawe during August 2000 CRAMP survey. Photo by Paul Jokiel. (Click image for larger view.)
A 100 m transect line is laid out along a consistent depth contour. Eleven stainless steel pins are placed to mark the “spine” or center of the transect from 0 m to 100 m along the transect. Plastic tubing slips over these pins as a reference point. In addition, one cable tie marks the center pin at the 0 m mark at the beginning of the transect, two ties at the 50 m mark and three ties are placed on the center pin at the 100 m mark at the end of the transect. This is done to aid in diver orientation on subsequent surveys. Pins marking each of the 10 randomly placed transects and each of the 5 randomly selected photoquads are also installed. Pins are secured with epoxy (z-spar marine epoxy) for permanent placement.
As can be seen from the above diagram, there are 50 possible transects of 10 m length that are determined by this grid. Ten of the 50 possible positions are randomly selected. Additional pins are installed only where needed to complete the array and mark the ends of the 10 transects. These are the 10 transects that will be monitored annually over time. In addition, five of the locations with pins are haphazardly selected for the installation of permanent photoquadrats.
An example of a randomly designed grid layout is shown below. The spine pins also determine the location of the reef fish transects. Rugosity is measured along the same 10 meter transects that are used for digital image monitoring.
Randomly designed grid layout. (Click image for larger view.)
Brown EK, Cox EF, Tissot B, Jokiel PL, Rodgers KS, Smith WR and Coles SL (2004) Development of benthic sampling methods for the Coral Reef Assessment and Monitoring Program (CRAMP) in Hawai‘i. Pacific Science 7: 145-158
|Photoquadrats -- Video Transects -- Rugosity Measurements -- Sediment Analysis|
Last Update: 04/21/2008
By: Lea Hollingsworth
Hawai‘i Coral Reef Assessment & Monitoring Program
Hawai‘i Institute of Marine Biology
P.O. Box 1346
Kāne‘ohe, HI 96744