Growth of the massive morph of Cliona nigricans (Schmidt 1862) (Porifera, Clionaidae) on different mineral substrata

Abstract

Mineralogy of substratum plays several roles on benthic organisms, affecting both their distribution and abundance. Here we studied the long-term effect of biogenic limestone, travertine and quartz on the growth of the massive stage of the boring sponge Cliona nigricans. Experiments were performed in the field, on a detritic bottom 40 m depth, where a population of the massive C. nigricans lives. Experimental sets of sponges with the same dimensions were maintained for 500 days on the three different substrata and a comparison among relative growth was performed. At the end of the experiment all the sponges incorporated gravels but the specimens buried into calcareous particles, both biogenic and not, and increased in size while dimensions of the specimens buried into quartz sand decreased. Our results show a negative effect of quartz towards the growth of this species and highlight once again that mineral composition of substratum can affect morphogenetic processes.