Research On Waterborne Settlement Pheromone Of The Barnacle Balanus Albicostatus

Barnacle is a kind of typical and harmful fouling organism,adhering strongly to artificial facilities in marine and causing huge damage.In marine,barnacles gather and aggregate.Aggregation with high density is one of the reason why barnacles are difficult to erase.Thus,study on the mechanism of aggregation of barnacles can not only explain how barnacles settle and aggregate,but also enlighten the prevention of barnacles.It's generally assumed that the aggregation of barnacles is caused by contact settlement pheromone and waterborne settlement pheromone(BWSP).At present,the contact settlement pheromone,SIPC(settlement inducing protein complex)has already been identified,but BWSP is still unclear.This study focuses on Balanus albicostatus,one common barnacle species in China.Isolation and identification of BWSP in adult barnacles conditioned water(BCW)were performed.Relationship between the BWSP and microorganisms on the shells of B.albicostatus was demonstrated.Studies on the effect of high temperature and acidification on the release of the BWSP by adult barnacles and the settlement inducing activity of the BWSP were conducted.Main conclusions were as follow.(1)Ultrafiltration,gel column chromatography,high performance liquid chromatography and liquid chromatography-mass spectrometer were used to analyze the BCW which can induce the settlement of conspecific cyprids.Two active compounds adenosine and inosine were identified.The LC-MS results showed that the concentrations of adenosine and inosine in BCW were 0.32 ?g/mL and 0.22?g/mL,respectively.Results of bioassay indicated that adenosine was responsible for the settlement-inducing activity of BCW on cyprids,which was a waterborne pheromone.(2)Twenty-one bacterial strains were isolated from the shells of B.albicostatus,of which Shewanella aquimarinaB17 and Shewanella aquimarina B21 were found to be effective on inducing the settlement of cyprids.On the other hand,Tenacibaculum mesophilum B8,Pontibacter.akesuensis B12,Pseudoalteromonas.Arabiensis B14,Shewanella aquimarina B16 significantly inhibited the settlement of cyprids.The combined effect of adenosine and biofilm on settlement of cyprids had been performed,which indicated that there were no combined effect between adenosine and biofilms.BCW and adenosine induced biofilm-forming of S.aquimarina B21,indicated that B.albicostatus may indirectly inducing the settlement of conspecific cyprids by promoting S.aquimarina B21 forming biofilm.(3)The rise of temperature between 26-30 degrees significantly induced the release of adenosine by adult B.albicostatus.Acidification had no effect on the release of adenosine by adult B.albicostatus.Rise in temperature between 26-34 degrees induced the settlement of cyprids of B.albicostatus.Acidification inhibited the settlement.Rise in temperature between 30-34 degrees inhibited the responds of the cyprids to waterborne pheromone.BCW relieved the settlement-inhibiting effect on cyprids by acidification.In conclusion,adenosine may be one waterborne pheromone released by adults barnacles to induce settlement of conspecific cyprids.Adenosine also promoted S.aquimarina B21 forming biofilm,this maybe an indirect mechanism of how adult barnacles induced settlement of conspecific cyprids.The activity of adenosine could be affected by the change of temperature and pH.