Long-term experimental in situ farming of Crambe crambe (Demospongiae: Poecilosclerida)

Background.ThemarinespongeCrambecrambe waschosenasanexperimentalmodel ofsustainableshallow-watermaricultureintheSardinianSea(WesternMediterranean) to provide biomass with high potential in applied research. Methods. Explants were cultured in four long-term experiments (19 and 31 months at ca. 2.5 m depth), to determine the suitability of new culture techniques by testing substrataandseedingtime(season),andmonitoringsurvivalandgrowth.Explantswere excisedandgrowninanexperimentalplantclosetothewilddonorspongepopulation. Percentagegrowthrate(GR%)wasmeasuredintermsofsurfacecoverarea,andexplant survival was monitored insitu by means of a digital photo camera. Results.Explantsurvivalwashighthroughoutthetrial,rangingfrom78.57%to92.85% ontravertinetilesandfrom50%to71.42%onoystershells.Afewinstancesofsponge regression were observed. Explant cover area correlated positively with season on two substrata, i.e., tiles and shells. The surface cover area and GR% of explants were measured in the starting phase and monitored up to the end of the trial. High GR% values were observed both on tiles (>21%) and on oyster shells (>15%). Discussion. The data on the behaviour and life-style of cultured fragments, together withanincrease>2,400%incoverarea,demonstratethatinsituaquacultureisaviable and sustainable method for the shallow-water biomass supply of Crambe crambe.