Abstract
Marine invertebrate larvae are highly phototactic during early stages of larval period and greatly influenced by light, colour and other physio-chemical properties of the substrates. In the present study, the effects of light and substrate colour on recruitment of marine invertebrates were investigated. Four different colour panels (red, green, blue and yellow acrylic sheets) and colourless panel (clear transparent acrylic sheet) were suspended at 2 m depth in the central Red Sea for 4 weeks during two seasons (spring and summer). The effects of substrate colour on invertebrate recruitment were tested under light and shade conditions. The results revealed significant variations in the recruitment of invertebrates between different colour panels and the panels exposed to light and shade. Higher densities of invertebrates were observed on the panels exposed to shade but the bryozoans abundance was high on the panels exposed to light. Tube worms and bryozoans preferred blue colour panels and the abundance of barnacles and bivalves were high on red colour panels. Significant interaction between substrate colour and light was observed in the abundance of barnacles, tube worms, bivalves and bryozoans. In conclusion, this study indicated the ability of some marine invertebrate larvae to discriminate coloured substrates depending on the light intensity.