Abstract: The behavioral responses of sea cucumber (Apostichopus japonicus) to different light intensity (100, 50, 10, 5, and 1 lx) and settlement substratum color (red, gray, yellow, blue, white, black, and green) were examined by mean phototactic rate (MPR) and mean attractive rate (MAR) methods. The results showed that the MPR was significantly different (P<005) among strong light regions (100, 50, and 10 lx) (P<005), but was not between weak ones (5 and 1 lx). Under natural light and darkness, the MAR of same color settlement substrata had no significant difference; while under the same light intensity, the MAR of black and grey settlement substrata was superior to that of the others, being significantly different with that of blue and yellow settlement substrata and of the control (P<001). The attractive effect of different color settlement substrata was in the order of black>gray>red>green>white>blue>yellow. The above results suggested that the MPR of A. japonicus decreased with increasing light intensity, representing the photonegative response of the organism. Among the seven colors settlement substrata, the black, gray, and red ones had the higher MAR.

Key words: Water stress, Sandy land, Pinus sylvestris var mongolica, Seed germination, Polyethylene glycol