A survey of coral communities was carried out in the American Samoa Archipelago to assess the current status of coral reefs and provide a rigorous quantitative baseline dataset for future monitoring of these reefs. Five replicate belt transects were used to estimate the size structure, density and percent cover of corals at 29 locations around Tutuila and Manu'a Islands during October and November, 1995.
Provide a status of the reefs for scientific and managerial purposes.
NOAA Supplemental: Entry_ID: Unknown Sensor_Name: SCUBA Source_Name: manual Project_Campaign: American Samoa Coral Ecosystem Assessment Originating_Center: Dept Marine & Wildlife Resources, American Samoa Storage_Medium: PDF, Quattro Pro, MS Word and Excel Online_size: 11520 kbytes Resource Description: NODC Accession Number 0001972
ground condition
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Dept Marine & Wildlife Resources, American Samoa
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Status of the coral reefs of the Samoan Archipelago
Status of the coral reefs
critical evaluation
Quantitative Survey
Field Surveys: Quantitative surveys of hard corals were carried out at 29 sites around Tutuila and the Manu'a Islands during October and November 1995. These surveys were designed to complement reef fish surveys currently underway in the American Samoa Archipelago (Green, in prep). At each site five replicate 20m x 0.5m belt transects were surveyed on the reef slope at 10m depth, except at Fagaitua where only three transects were surveyed. All transects were located randomly within sites as it has been shown that random transects within fixed sites are as effective and more efficient for long-term monitoring of corals than fixed transects (Mundy 1991; see also Green 1989). In addition to reef slope surveys, coral communities were surveyed at two sites on the reef flat at Manu'a Islands (Olosega and Ofu) and at two sites on the reef flat at Tutuila (Fatumafuti and Nu'uuli). A single lagoon site was surveyed on Tutuila at Faga'alu at approximately 4m depth. Detailed descriptions of all sites and transect locations can be found in Green (in prep). Each transect was surveyed by laying a 20m fibre tape close to the substratum parallel to the reef edge. A coral was considered to be within the transect if the centre of the colony lay within 25cm of either side of the tape. All corals within the belt were identified to species where possible, and the maximum diameter of each colony was measured and placed in one of seven size classes as shown in Table 1. Table 1. Size categories and corresponding colony size used to record size of colonies in belt transects. Size class Colony size 1 <= 5cm2 > 5 cm and <= 10 cm3 > 10 cm and <= 20 cm4 > 20 cm and <= 40 cm5 > 40 cm and <= 80 cm6 > 80 cm and <= 160 cm7 > 160 cm. Data analysis: Transect data were used to estimate colony density, population size structure, and percent cover for each species at each site. The midpoint of each size class was used to calculate the approximate area of each colony. Percent cover was calculated by expressing the sum of the areas for each species as a proportion of total transect area (10m2). Multivariate analyses were used to identify patterns in coral community structure around the islands of American Samoa. Cluster analysis (flexible UPGMA) and Multi-dimensional scaling (non-metric) (MDS) were used to test for effects of habitat (reef flat vs. lagoon vs. reef slope) and exposure (NW, NE, SW, SE, Manu'a; on coral community structure. Cluster analyses and MDS were based on Bray-Curtis similarity matrices using species densities (mean number of colonies per site) and the average percent cover of each species at each site. Green, A.L. 2002 Status of the coral reefs of the Samoan Archipelago: Report to the Department of Marine and Wildlife Resources, PO Box 3730, Pago Pago, American Samoa. 96799, 85pp. Green, A.L. 1996 Status of the coral reefs of the Samoan Archipelago: Report to the Department of Marine and Wildlife Resources, PO Box 3730, Pago Pago, American Samoa. 96799, 120pp. Mundy, C.N. 1991. A critical evaluation of the Line Intercept Transect methodology for surveying sessile coral reef benthos. Msc Thesis. James Cook University of North Queensland. 127pp.Mundy, C.N. 1996. A Quantitative Survey of the Corals of American Samoa: Report to the Department of Marine and Wildlife Resources, PO Box 3730, Pago Pago, American Samoa. 96799, 33pp.
files are found in directory ../../dataFILENAME FORMAT HISTORY CONTENT App_raw1.wb1 Quattro Pro Original Raw Data App_raw1.xls MS Excel Copy sameApp_raw1.csv ASCII CSV Copy sameSamoa201995.pdf PDF Original ReportSamoa201995.doc MS DOC Copy sameSamoa201995.txt ASCII Text Copy sameSite_Locations.xls MS Excel Original LocationsSite_Locations.csv ASCII CSV Copy sameNote, the Site_Locations.xls was acquired from the dataset(A.Green, 1996).
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