Little R Code for quantitative dissimilarity coefficients (Legendre et al. 2015)

Really interesting paper by Pierre Legendre and co-authors- Thirty-year recovery of mollusc communities after nuclear experimentations on Fangataufa atoll (Tuamotu, French Polynesia. Great paper for the community ecologists. Friend is trying to do a similar thing with the before-after analysis. The authors provide a how-to guide to answer this question of the paper: "We analysed the survey data (electronic supplementary material, appendix S1) to answer the following question: after the nuclear tests, were the assemblages generated during primary succession similar to those found before the tests?" Legendre provided his own code on his website , and I modified the code for my own work. All credit goes to Legendre.