[Coral-List] Accuracy of Point Count in Monitoring Ecosystem Change

Phil Dustan dustanp at cofc.edu
Wed Feb 1 09:19:53 EST 2012

Dear Listers,
     I'd like to draw your attention to a new online publication that 
evaluates the robustness of a commonly used method to estimate benthic 
cover: point counting which is particularly used in large-scale, 
long-term coral reef monitoring projects such as the Florida Keys Coral 
Reef Evaluation and Monitoring Project. In short it explores the error 
limits of point counting  in a world of degrading coral reefs:

Getting to the Point: Accuracy of Point Count in Monitoring Ecosystem 
Change  by  Eric Pante and Phillip Dustan
Journal of Marine Biology,  Volume 2012 (2012), Article ID 802875, 

   While some authors have addressed questions on the statistical 
sensitivity of point counting under specific conditions, the general 
robustness of the method has never been tested to the best of our 
knowledge. In this communication, we report results from computer 
simulations based on real data from the Bahamas that strongly suggest 
that the number of points needed to robustly estimate benthic cover 
depends on overall cover and benthic heterogeneity, and therefore, the 
point-counting effort (number of points being identified) must be 
tailored to fit particular conditions. Our results indicate that the 
sampling density  must be _increased_ as reefs degrade in order to 
maintain the same level of accuracy and precision.  Thus it is important 
that  investigators  periodically re-evaluate point-counting parameters 
when benthic cover is expected to vary over the course of the monitoring 
project to insure valid data.
    We hope that the results of this communication will motivate the 
community to better justify their sampling design when using point 

 The paper may be accessed directly at:


Phillip Dustan  Ph.D.
Department of Biology
College of Charleston
Charleston   SC  29424
(843) 953-8086 voice
(843) 953-5453 (Fax)

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