Determination of the physical parameters of coral distributions using line transect data

Abstract

We present a new method for extracting a comprehensive suite of biologically significant parameters from line transect data of coral communities. In addition to the percentage coral cover (the traditionally extracted parameter), the method extracts the population density of the coral colonies, their mean diameter and associated standard deviation and, for adequate data, their size frequency distribution. The method assumes only that the coral colonies form a system of non-overlapping circles in the plane, that the diameters of the circles are random quantities with an unknown distribution function, and that the transects are placed randomly. We test the method on both theoretical and real data to show that it performs as well as, if not better than, current methods in extracting the traditional parameter as well as being able to extract the additional useful parameters indicated. Because the method makes few restrictive assumptions and seems robust when used with field data, we suggest that it has wide application wherever line transects are used for ecological survey. The method is implemented in a Fortran program available from the senior author.