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Development of Benthic Sampling Methods for the Coral Reef Assessment and Monitoring Program (CRAMP) in Hawai'i
|Title:||Development of Benthic Sampling Methods for the Coral Reef Assessment and Monitoring Program (CRAMP) in Hawai'i|
show 3 moreTissot, Brian
Coles, Steve L.
|Issue Date:||Apr 2004|
|Publisher:||University of Hawai'i Press|
|Citation:||Brown E, Cox E, Jokiel P, Rodgers K, Smith W, Tissot B, Coles SL, Hultquist J. 2004. Development of benthic sampling methods for the coral reef assessment and monitoring program (CRAMP) in Hawai'i. Pac Sci 58(2): 145-158.|
|Abstract:||The Coral Reef Assessment and Monitoring Program (CRAMP) of
Hawai'i was established in 1998 to monitor long-term changes in coral reef
benthic communities around the state. Development of the methodology involved
analysis of results from previous monitoring programs in Hawai'i to determine
precision and statistical power of various methods to detect change.
Additional field trials were conducted to examine factors such as repeatability,
appropriate transect length, number of transects, number of samples per transect,
cover estimation techniques, observer variation, as well as time and financial
constraints. Benthic monitoring methods used previously in Hawai'i
generally showed low statistical power for detecting change due to low precision
and small sample size. Field trials indicated that repeatability of conventional
techniques using transects or quadrats had high variation and consequently low
statistical power unless efforts were made to reposition the sampling units with
greater precision. Longer transects (e.g., 25 and 50 m) had higher variability
than shorter transects (e.g., 10 m), suggesting that smaller sampling units were
more appropriate for the habitats sampled. Variability among observers analyzing
the same data was low in comparison with other sources of error. Visual
estimation techniques showed low initial cost but were inefficient per survey.
Digital video required the highest initial monetary investment but yielded the
greatest quantity of data per survey with sufficient quality. The cost effectiveness
of the digital video method compared with other techniques increased with
more surveys and in more remote situations where logistical expenses were incurred.
A within-habitat stratified random sampling design was implemented for
the CRAMP design. Fixed transects were chosen to reduce temporal variance
and allowed efficient resurveying under the high-wave-energy field conditions
typically found in Hawai'i. The method was designed to detect an absolute
change of 10% in benthic cover with high statistical power using 50 points per
frame, 20-30 frames per transect, and 8-10 transects per depth. Fixed photoquadrats
with high precision and high resolution were included in the design to
allow detailed monitoring of coral/algal growth, recruitment, and mortality.
|Appears in Collections:||Pacific Science Volume 58, Number 2, 2004|
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