Competitional settlement of brown alga Iyengaria stellata and soft coral Zoanthous sansibaricus on muddy and muddy-rubble intertidal substrate in the Hormuz island

Abstract

The effect of substrates on the surface cover by the soft coral, Zoanthus sansibaricus, and the brown alga, Iyengaria stellata, and their competitional condition, was compared in Hormuz Island by estimating of coverage area in 40 quadrates (50×50 cm). This soft coarl (Zoanthid) is a dominant species in the island’s intertidal zone and I. stellata is a dominant macroalgea most of the year. Significant negative correlation (p<0.01; r =-0.607) revealed competition between the two species for settlement on the two substrates. Soft coral with 61.7% coverage was dominant vs. 16.8% for brown algae on muddy-rubble substrate, but on sandy-rubble substrate, the brown algae was dominant with 37.8% coverage vs. 19.5% for the soft coral. It seems that better competitional conditions in settlement on unconsolidated substrate have some advantages for Z. sansibaricus.