Changes in algal coverage and sea urchins fauna, density of turban shells and abalone in Diadema removal area of Haidaura Bay, Mie Prefecture

Abstract

The effects of removing long-spined sea urchin species of the genus Diadema on regeneration of seaweeds were investigated in barren rocky areas in Haidaura Bay, Mie Prefecture, central Japan from February 2010 to December 2019. Diadema spp. were removed by diving and capturing from ships. Algal coverage and density of sea urchins, turban shells and abalone were monitored. Reduced density of Diadema spp. resulted in increased algal coverage in the area where sea urchins had been removed. In addition, the density of sea urchins other than Diadema spp. and the total number of sea urchin species increased under low Diadema spp. densities. Turban shells and abalone started to appear after the algal coverage increased.