Water flow and the distribution and abundance of echinoids (genus Echinometra) on an Hawaiian Reef

Abstract

Echinometra oblonga and E. mathaei, two rock-burrowing sedentary echinoids, live in positive association on an Hawaiian algal reef. E. oblonga dominates in rough water, E. mathaei in calmer water. The distribution and abundance of these two species of echinoids is significantly correlated with water flow over the reef and with detrital algae being deposited in their burrows. The mean size of each species increased with increase in water flow. E. mathaei and E. oblonga show no significant difference in the rate in which biomass increases with test diameter.