Annual Reef Monitoring Design |
Layout of transects For each reef, 1 to 5 zones (depths) parallel to the coastline are selected. Zone 1 is the shallowest at 1 m below the lowest low tides. The remaining zones are at 2m, 5m, 10m, and 20m with respect to the first zone, but may vary depending on reef structure and depth gradient. The design is adapted from Loya (1978) but uses quadrats. In each zone, three belt-transects 10m long and 10 meters apart are monitored, all at the same depth and parallel to the coastline. Each transect is marked at the beginning, middle, and end with a permanent metal rod driven into the reef. Ten quadrats are measured along each transect with successive placements of the frame along the shoreward side of the tape. There is no space between frame placements. A one meter square PVC quadrat divided with string into a 10x10 cm grid (100 cm 2, or 1% of the quadrat, for each grid square) is used for censusing each transect. To conduct the survey, the PVC frame is placed on the reef with the seaward edge adjacent to a metric tape cable stretched between the marker bars and starting with end of the transect furthest to the right, facing the shore. The percent area of each type of cover for all sessile organisms is estimated as a fraction of a grid square. Hence a colony of size 25cm 2 would be 1/4 of a square and be recorded on the data sheet as 0.25. |
Recording data For each colony or type of cover in the quadrat, record the taxon name (to species level if possible), the area in fractions of a grid square, and if there is more than one colony of this size, the number of colonies. If a colony extends outside of the frame, or into an adjacent frame, record the area of the part of the colony that is within the frame only. A large colony extending over two quadrats will then be counted as two smaller colonies and no attempt is made to record the total size of a colony. If a colony or algal frond extends above the plane of the frame, record the attachment area only (i.e. gorgonians, sponges). If one colony is growing over another colony, record only the uppermost. Coral colonies less than 5 cm 2 (0.05 grid square) are considered recruits. The last entry for a quadrat is the background cover and its area is not recorded directly but is calculated later. Algae are divided into four groups, calcareous, crustose coralline, turf, and frondose (macro). Corals, ocotocorals and sponges are recorded to species if possible. Taxon names are recorded in the field as an abbreviation that is unambiguous to the people collecting and entering the data. A standard code is assigned to the taxa as part of the data entry procedure. |
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Last revised: June 1, 2005 |