 About AIMSResearchFacilitiesNewsSearchSite mapSite index   |
Part One: Manta Tow Technique
COTS and CORAL SURVEYS The manta tow technique is used to provide a general description of large areas of reef and to gauge broad changes in abundance and distribution of organisms on coral reefs. The advantage of manta tow over other survey techniques is that it enables large areas of reefs to be surveyed quickly and with minimal equipment. The technique involves towing a snorkel diver (observer) at a constant speed behind a boat (Figure 1). The observer holds on to a 'manta board' attached to a small boat by a 17 metre length of rope. This person makes a visual assessment of specific variables during each manta tow (2 minutes duration), and records these data when the boat stops, on a data sheet attached to the manta board. The manta tow technique was developed in 1969 to assess crown-of-thorns starfish densities on reefs in Micronesia (Chesher 1969). Similar studies were done in the Red Sea (Roads & Ormond 1971), Micronesia (Goreau et al. 1972) and on the Great Barrier Reef (Endean & Stablum 1973). Since the 1970's, the manta tow technique has been used extensively on the Great Barrier Reef for broadscale surveys (at the scale of entire, or large part of, reef). A study by Moran et al. (1988) to assess the distribution and abundance of crown-of-thorns starfish (COTS) and corals on the Great Barrier Reef led to a standardisation of the technique at AIMS. Studies by Fernandes (1989, 1990), Fernandes et al. (1990), and Moran and De'ath (1992) have shown the manta tow technique to be a relatively accurate and cost effective way of determining the abundance of non-cryptic COTS and corals over large areas, in clear water. Moran & De'ath (1992) found that the counts of COTS from manta tow surveys can be calibrated to predict estimates obtained from more intensive searches using SCUBA.
web@aims.gov.au |
Figure 1. The manta tow technique.