Supplement 1. Bivalve data (Legendre et al. 1997) used for example application.

File List bivalve.txt Description The ASCII text data frame bivalve.txt contains 200 rows of observations corresponding to the 0.25 square meter sample plots on a 250 m × 500 m area on the sandflat of Wiroa Island, Manukau Harbor, New Zealand (data from Legendre et al. 1997). The 21 column variables are: LN.MACG15, logarithm of counts of <i>Macomona</i> &gt;15 mm; MACG15, counts of <i>Macomona</i> &gt;15 mm; ELEV.M, bed elevation in meters above chart datum; ELEV2, ELEV.M squared; ELEV3, ELEV.M cubed; X.CTR, longitude coordinates centered to mean 0; Y.CTR, latitude coordinates centered to mean 0; X2, X.CTR squared; XY, X.CTR multiplied by Y.CTR; Y2, Y.CTR squared; X3, X.CTR cubed; X2Y, X2 multiplied by Y.CTR; XY2, X.CTR multiplied by Y2; Y3, Y.CTR cubed; EBBSTRESS, ebb tide bed shear stress (N/m²); SWWAVEWORK, southwest wave work per unit of bed area (kg/s²); WSWWAVEWORK, west, southwest wave work per unit of bed area (kg/s²); WATER.G20CM, proportion of time the plot is covered by water &gt;20 cm deep during spring tide (0 - 1); LRGWAVE.STIR, proportion of time large waves stir the plot during spring tide (0 - 1); FLDSTRESS, flood tide bed shear stress (N/m²); and SHELLHASH, bivalve shell hash (g) in the bed sediment. Missing values are indicated by NA.