Guam Long-term Coral Reef Monitoring Program Benthic Percent Cover Derived from Image Analysis since 2010

The Government of Guam's Long-term Coral Reef Monitoring Program, coordinated through the Guam Coastal Management Program until October 2013 and now coordinated through the University of Guam Marine Laboratory, involves the collection of data for a suite of coral reef ecosystem health parameters at several high priority reef sites around the island of Guam. Various coral reef surveys are carried out on an annual or biennial basis along the seaward slope between 7 and 15 m depth in the Tumon Bay Marine Preserve, East Agana Bay, the Piti Bomb Holes Marine Preserve, the Achang Reef Flat Marine Preserve, and the eastern side of the Cocos Barrier Reef (Cocos-East). Data collection is also carried out on a less frequent basis along the seaward slope (5-8 m) in Fouha Bay and along the reef margin (1-2 m) and slope (2-15 m) of Western Shoals, in Apra Harbor. The surveys, which are conducted by University of Guam Marine Lab and NOAA PIRO biologists at numerous permanent and non-permanent sampling stations within each site, currently include benthic photo transects, quadrat surveys for coral colony size and condition, stationary point count fish surveys, macroinvertebrate belt transects, and chain-length rugosity surveys. The data products described herein document the status and trends for benthic cover and composition at the monitoring sites mentioned above. Benthic cover and coral and algal generic diversity are currently assessed using digital photo transects. The still images provide a permanent record of the transects and are quantitatively analyzed using Coral Point Count with Excel extensions (CPCe; Kohler and Gill, 2006) point sampling software to obtain benthic cover estimates. Power analyses support the methodological approach, whereby statistically sound benthic cover estimates can be successfully derived. Benthic percent cover is calculated at the sampling station level (= one 25 m transect) for data derived from benthic images. Benthic percent cover has been derived from images collected at sites during surveys from 2010 through 2012 and quality control has been completed for these data. Additionally, benthic cover data has also been derived from images collected at sites during surveys in 2014, but quality control has not yet been completed for these , and analysis of images collected during 2015 surveys is currently underway. Surveys were not carried out in 2013.