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. Fish are a culturally and economically valuable resource for the island of Guam (van Buekering et al., 2007). In recognition of the high value of this resource, reef fish surveys are a key component of the Guam Long-term Coral Reef Monitoring Program. Reef fish assessment 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 uses a Stationary Point Count Method, adapted from Ault et al. (2006) and NOAA Fisheries, Coral Reef Ecosystem Division (Williams et al., 2011), to conduct the reef fish surveys. These monitoring data on reef fish communities provide results on fish density, biomass, and diversity; allow for exploration of community structure by functional group and size structure; and can be used to detect changes in fish communities over time.
The reef fish 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.
Fish surveys have been conducted in the summer months starting in 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 September 26 2012 at 4 stations ranging in depth from 6 to 12 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 each site were made by divers who have been trained, and met minimum standards in identifying species present at the survey locations and in estimating size of fishes in survey counts. However, all species identifications are made visually, sometimes in situations where a fish is only briefly seen. Observations, including species identification and sizing, were periodically checked for consistency between divers, and little discrepancy was noted between divers. Data is checked after each survey season, but there remains some possibility of typographical or other errors. The surveys are conducted by taxonomic experts, but when field technicians do not possess the requisite taxonomic expertise, photos of specimens that cannot be identified by field personnel are provided to taxonomic experts for identification.
The same methods of data collection were used at each of the stations surveyed, with some minor changes over time to refine data collection as described below in the process description. Surveys were conducted by a team of scientists that met minimum qualifications and trained and calibrated together. Examination of the early data show minor diver bias associated with surveyor experience. More experienced surveyors had higher species diversity and thus biomass. Steps have been taken to increase training time for new surveyors and improve calibration to minimize this bias.
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 collected in 2012 and 2014 has not yet been entered or quality controlled (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
The fish team uses a Stationary Point Count Method (SPC) adapted from Ault et al. (2006) and NOAA Fisheries Coral Reef Ecosystem Division (Williams et al., 2011) at all stations. The modified method is documented in the Final Status Report that was prepared by the Guam Long-term Monitoring Program Coordinator to close out a fiscal year 2010 grant from the Coral Reef Conservation Program (https://www.ncei.noaa.gov/data/oceans/coris/library/NOAA/CRCP/other/grants/MonitoringGrants_FY10_Products/NA10NOS4260046_GuamLTMP_ProgressReport_3-8-12.pdf), the relevant details of which are provided below. 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 conduct the reef fish surveys divers are positioned at 7.5 m and 22.5 m along the transect and count fish within a 7.5 m radius cylinder extending from the substrate to the limits of vertical visibility. The simultaneous surveys start once the divers deploy the transect and both divers are ready to proceed. 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. The SPC surveys are conducted in two parts. During the first five minutes, divers record all species observed within the cylinder, but do not count or size fish. All fish are identified to species level or the next lowest taxonomic level possible (genus or family). If a rare fish (shark, species of concern, large mobile predators, etc.) is observed during the first 5 minutes, it is counted and sized, but the diver notes that it was not an instantaneous count (This survey method for rare fish was not in place during the Tumon Bay and East Agana Bay surveys. Rare fish were counted and sized but it was not clear if it was an instantaneous count or not.) After the first five minutes divers enumerate fish, one species grouping at a time, using rapid visual sweeps of the plot. The counts are designed to be instantaneous to avoid double counting. All fish of the target species within the SPC boundaries are counted and sized to the nearest centimeter; however, divers use size classes for large schools or high densities. This process is continued until all of the listed species are counted. If a species is no longer present in the cylinder during the second phase, divers record their best estimate of size and number. During the Western Shoals surveys, this type of count was marked as noninstantaneous and excluded from the biomass and density calculations. At the end of the survey, divers swim throughout the 7.5-m radius plot to enumerate small and cryptic species that were not captured from the stationary central position. If a rare fish is still present during the counts, it is counted and sized and the original measures are crossed off. Species that enter the SPC after the first five minutes are noted on the species list for the site, but are not counted unless they are a rare fish recorded with a noninstaneous designation. Surveys are not completed if the visibility is less than 7.5 m. To document species richness at the sites, the fish team conducts roving diver swims throughout the survey station after the SPCs. For the first two monitoring sites in 2010, Tumon Bay and East Agana Bay, fish divers also conducted belt transects along the transect lines prior to conducting SPCs. As the fish divers deployed the transect line they recorded the species, number, and size of all fish greater than 20 cm in length within 5 m of the transect (25 m x 10 m). They then returned along the transect counting and sizing all fish less than 20 cm within 1m of the transect (25 m x 2 m). Fish were identified to species or next lowest taxonomic level and sized to centimeter. Once the belt transects were complete, the divers conducted the modified SPC method as described in the Process Description section of this metadata record.
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.
