Sponges of economical interest in the Eastern Mediterranean: an assessment of diversity and population density

Abstract

The aim of this paper was to investigate diversity and population density of sponges with manifest or potential economical interest for the first time in the Eastern Mediterranean. For this purpose, the area of Dodecanese, an Aegean area traditionally harvested for sponges was surveyed for bath sponges and species known as sources of bioactive compounds. Twenty stations of diverse orientation, substrate inclination and type of substratum, located on seven islands, were surveyed and totally 36 demosponge species were found. The data, collected with a non-destructive method, were subjected to multivariate analysis which showed that sponge diversity was higher in areas with vertical cliffs. A considerable spatial variation was revealed by the formation of two groups of stations, according to sponge species presence/absence: one including vertical cliffs and a second one, including moderately inclined cliffs, Posidonia meadows and detritic biogenic bottoms. Bath sponges occurred at a restricted number of stations and although in relatively low population densities, they revealed a sign of recovery after the devastating epidemic events. Higher stock availability was found for six biotechnologically promising species which were distributed all over the study area. The above results are encouraging for a future sustainable stock exploitation and open a new perspective for sponge mariculture in the area.