Manta tow survey

Manta tow involves towing a snorkel diver behind a small boat along the upper reef slope to make direct observation on the distribution of corals in a broad scale. Although obtained data are qualitative, e.g. 5 coral cover categories presented in the table below, they can provide general description of coral communities and disturbances such as the occurrence of the Crown-of-Thorns Starfish and coral bleaching. The rapidness is also an advantage of Manta tow. We usually complete Manta tow within 2 hours to cover about 5 km reef slope habitats in the survey area.

Manta tow results
Download "manta" (kmz format, 352 b)
Manta tow survey

Manta tow tracks and coral cover changes can be viewed on Google Earth
Download Google Earth

Manta tow tracks and coral cover changes can be viewed also on Google Map

Manta tow procedure


Manta tow is carried out by a snorkel diver and an assistant on a boat. The snorkel diver holds on to a "manta board" attached to a small boat by an about 10-15 meter rope. While the boat runs along the upper reef slope (3-8m depth) at the speed of 6-8km/h, the diver makes a visual assessment of coral cover categories and other variables (see the table below). The diver records these data when the boat stops every 2 minutes, on a data sheet attached to the manta board. At the same time, the assistant records the position coordinates and time using a portable GPS. The GPS is set to record the boat track automatically.

Manta tow results

2006 Results          2007 Results

manta2006  manta2007

2008 Results         2009 Results

manta2008  manta2009

2010 Results         2011 Results

manta2010  manta2011

2012 Results         2013 Results

manta2012  manta2013

2014 Results