Permutational multivariate analysis of variance (PERMANOVA) on epibenthic fish species composition among 3 deep-sea surveys conducted between 1964 and 2002 in the northern GoM.

Two-way mixed model PERMANOVA were employed for (a) the east and (b) the west central areas which roughly overlap for all 3 surveys (Fig. 1). The random factor used two depth intervals separated by the 840-m depth contour in the east area and 900-m depth contour in the west central area. For a limited number of sites, the most current DGoMB study repeated the historical NGoMCS or R/V Alaminos sampling; hence, randomized complete block (RCB) PERMANOVA was conducted on (c) Station W1, W3, WC5 and WC12, (d) Station C1, C7 and C4, (e) Station S41, S42 and S43, and (f) S35, S36, S37 and S38 to examine the temporal variation on fish species composition. The blocking factor for the RCB PERMANOVA used different sites along the selected transects.