The Government of Guam's Long-term Coral Reef Monitoring Program, coordinated by the Guam Coastal Management Program until October 2013 and now coordinated by the University of Guam Marine Lab, 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, including Tumon Bay, East Agana Bay, Piti Bay, and Western Shoals. Sites at Fouha Bay, the Achang Reef Flat Marine Preserve, and the Eastern seaward slope near Cocos Island will be established in 2014. Data are collected annually or biennially by a team of highly-trained field biologists from the Guam Coastal Management Program, the NOAA Pacific Islands Regional Office, the University of Guam Marine Lab, and with occasional assistance by staff from other agencies. Corals are the main contributor to coral reef accretion, provide critical habitat for numerous reef organisms, and serve as a food source for some reef organisms. In recognition of the critical important of corals, coral colony size and condition surveys are a key component of the Guam Long-term Coral Reef Monitoring Program. Coral colony size and condition surveys have been conducted at high priority reef sites around Guam since August 2010. The surveys are carried out at numerous sampling stations within each monitoring site, the locations of which were generated randomly using a Geographic Information System and the relevant bathymetric and benthic habitat data. A split-panel approach is currently used for the sampling design, with half of all sampling stations in a given site being fixed and half re-randomized every visit or every other visit. The monitoring team assesses the size and condition of all coral colonies found within quadrats placed every 5 meters along 25-m transects (15-m transects for the Western Shoals site). These monitoring data on coral communities provide results on coral colony density, size, condition, and diversity; allow for exploration of community structure by functional group and size; and can be used to detect changes in coral communities over time.
The coral quadrat data are collected as part of the Guam Long-term Coral Reef Monitoring Program, which documents a number of important parameters related to ecosystem health; these parameters are grouped into three categories: water quality, benthic habitat, and associated biological communities. Many of these parameters are indicators of stressors, and significant changes in these parameters will likely raise concern and possibly trigger management actions. Data collected for these indicators provide important information about the resilience of high priority reef areas around Guam. Monitoring these parameters allows resource managers to evaluate the effectiveness of specific management strategies, and inform the development of new management actions.
Coral colony size and condition surveys have been conducted since 2010 at: Tumon Bay from August 4 to September 3 2010 at 20 stations ranging in depth from 5 to 15 meters and from September 5 to November 9 2012 at 21 stations ranging in depth from 6 to 15 meters East Agana Bay from September 7 to November 26 2010 at 20 stations ranging in depth from 5 to 15 meters and from November 16 to November 28 2012 at 10 stations ranging in depth from 8 to 15 meters Western Shoals from July 11 to August 19 2011 at 23 stations ranging in depth from 0.9 to 18 meters. Piti from July 23 to August 31 2012 at 20 stations ranging in depth from 7 to 13 meters. Surveys were not conducted in 2013, and are currently in progress for 2014 (as of the publication date of this document).
Ground Condition
Please cite the Guam Coastal Management Program when using data collected prior to October 2013. Guam Coastal Management Program, Guam Bureau of Statistics and Plans, Government of Guam.
Marine Laboratory - University of Guam
Marine Laboratry University of Guam
Guam Coastal Management Program, NOAA Pacific Islands Regional Office, and University of Guam Marine Lab.
Observations at all sites between 2010 and 2012 were made by the monitoring program coordinator, who specializes in Guam's coral communities. Species-level identifications likely became more accurate over time, but the accuracy of genus level identifications remained high through time.
The same methods of data collection were used at each of the stations surveyed, with the exception of surveys at the Western Shoals site, for which larger (1 m x 0.75 m) quadrats were used. All coral quadrat surveys conducted between 2010 and 2012 were carried out by the monitoring program coordinator, who specializes in Guams coral communities. Species-level identifications and coral health assessments likely became more accurate over time, but minor improvements in skill are not expected to have a significant impact on data quality.
Only hard-bottom habitats are surveyed. Surveys have been conducted every year between 2010 and 2014, except for 2013. Data entry and quality control are complete for surveys conducted through 2011; data entry and quality control of data collected in 2012 and 2014 is in progress (as of the publication date of this doucment).
5-10 meters as determined by GPS Unit Instrument parameters
Dive computer and analog SCUBA depth gauge
Instrument parameters
Coral colony size and condition surveys are carried out at all sampling stations. All sampling stations have been selected in hard-bottom habitats using a stratified random sampling design, and the stations have been designed using the split-panel approach (combination of fixed and non-fixed transects). Each sampling station is located using a GPS receiver. Upon reaching a given station, a small weight and line tied to a buoy is carefully lowered to the ocean floor. In optimal situations where four divers are available, two divers enter the water first to carry out the fish surveys. Starting at the weight tied to the buoy, a 30-meter transect is laid out. The transect is laid out in a clockwise direction relative to the island, following the depth contour if it is readily determined; if the area is relatively flat and a depth contour is not readily discernable the transect is laid at an angle parallel to the reef margin (which is determined prior to entering the water). Compact digital point and shoot cameras and housings are used by individual observers to document unknown organisms, incidences of coral disease, and species/behaviors of special interest. For the initial establishment of fixed sampling stations, 24 inch rebar is installed at the beginning of the transect and 12 inch rebar is installed at the center and end of the transect; four-inch concrete nails are installed at two of the corners of each quadrat used for coral size and condition surveys. For the Western Shoals site, rebar and concrete nails were not used and instead a small PVC float was tied to dead coral with a line at the beginning of the transect and large zip ties were placed at the beginning, middle, and end of the transect. Two small zip ties were used to mark two corners of each permanent quadrat location. To minimize diver disruptions, the two divers conducting the benthic surveys enter the water approximately 20-30 minutes after the divers conducting the fish surveys, once the fish team has finished enumerating fish. In situations where only three divers are available, all three divers enter the water at the same time and remain as a three-person buddy team to ensure diver safety throughout the survey. A fish diver partners with a benthic diver when two fish divers are not available. In this situation, the fish diver lays the transect and conducts the first SPC at 22.5 m while the benthic diver works from 0-15 m; they then switch positions along the transect. Shortly after a benthic team diver begins the photo transect, another diver then identifies and measures all coral colonies within 0.5 x 0.5 m quadrats placed at 0 m, 5 m, 10 m, 15 m, and 20 m along the right side of the transect. In rare instances time limitations prevent data collected for all five quadrat positions. For each quadrat location, the bottom-left corner of the quadrat is coincident with the appropriate meter mark (0 m, 5 m, etc.) along the transect. Only those colonies whose geometric center is within the quadrat are counted. Percent old dead, percent recent dead, and disease type and severity are recorded for each colony. The cause of tissue mortality is also noted if it can be determined with a reasonable degree of confidence. Measurements of the longest dimension and the width of the colony perpendicular to the longest dimension are made. An effort is made to carefully count all coral recruits/juvenile corals in order to assess the rates of coral recruitment to natural substrate. Care is taken to prevent the count of remnants of larger colonies as coral recruits/juvenile corals. Any tissue isolate suspected of being a remnant of a larger colony will be noted as such, in order to prevent the calculation of erroneous coral recruitment rates. At least two planar view photos are taken of each quadrat in order to maintain a photographic record of all quadrats. Photos are also taken of corals for which species identification, of unidentified sources of mortality, or of species or conditions of particular interest.
While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. The Guam Coastal Management Program makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
Contact Guam Coastal Management Program Coordinator for information. Data are available in xls (Microsoft Excel worksheet) or csv (comma-separated values) format