Supplement 1. Data and R script for reproducing the correspondence analysis of raw data and a video file showing the transition from regular to "raw" correspondence analysis (CA-relative to CA-raw).

File List CAraw_data.csv<br> CA_raw.R<br> CA_rel_to_raw.swf Description The CAraw_data.csv file is a comma-delimited data file containing the benthic abundance data analyzed in the statistical report.<br> --- Rows are the 13 sampling stations (stations R40 and R42 are references)<br> --- Columns are the 92 species, with abbreviated latin names<br> Note that the first row contains the 92 column names, and the first column the 13 site names. Thus there is one fewer item in the first row, which is convenient for reading with the read.table function in R. The CA_raw.R file is an R script for performing the computations of CA-raw. The CA_rel_to_raw.swf file is a video file showing the transition from CA-relative (the usual form of correspondence analysis) to CA-raw. (This video in shockwave flash format can be opened in a browser such as Firefox).