Potential Of Marine Sponge, Hymeniacidon Perleve As Bio-remediator And Bio-monitoring Specie In Integrated Aquaculture Ecosystem

Diseases of aquaculture organisms and negative environmental impacts of pollutants in aquacultural water areas are two key factors that restrain the increase in marine aquaculture production. As the oldest metazoan, sponges (Porifera) possess extreme abilities of pumping water to extract food and defense/immune mechanisms against a large number of pathogens in seawater. Using an inter-tidal marine sponge Hymeniacidon perleve as a model system, this thesis aims to (1) investigate the characteristics of sponges as bioremediators to remove pathogenic bacteria, organic matters, and inorganic nutrients (N and P); (2) clone H. perleve14-3-3 mRNA as biomarker to biomonitor pathogenic bacteria in seawater. In the laboratory we demonstrate that the feasibility of using sponges as bio-remediator and bio-monitoring specie in integrated aquaculture ecosystem.To examine a biomarker from marine sponge H. perleve in response to pathogenic bacteria in seawater, three partial 14-3-3 cDNA and partial 18s RNA of H. perleve were cloned and sequenced. The expression of 14-3-3 mRNA when exposed to non-infectious bacteria E. coli was not significantly different from that of control. However, the expression of 14-3-3 mRNA when exposed to infectious bacteria V. anguillarum II and V. alginolyticus was down-regulated respectively. The results demonstrated for the first time that sponges could differentiate the infectious bacteria from non-infectious bacteria using the 14-3-3 mRNA transcript level as a biomarker.The tests of H. perleve retaining and digesting pathogenic bacteria showed that H. perleve removed 96% of E.coli with initial density 7.0-8.3×106 cells/mL during 10.5 h, and kept the pathogens growth under control at initial density 6.3×105 cells/mL of 200 mL SNSW. E. coli and V. anguilarumⅡstained by fluorescence dye DiI were respectively fed to sponge. The laser confocal microscopy observation confirmed that the sponges filtering-retained and digested these bacteria by phagocytosis. For natural seawater (NSW) with mixture of different kinds of pathogenic bacteria, H. perleve exhibited the ability of retaining and digesting E. coli, Vibrio and Total bacteria.The tests of removing TOC in SNSW demonstrated that H. perleve could effectively removed DOMD at concentrations lower than 500 mg/L, and that the maximum removal capacity of TOC was 25.50 mg/g-fresh sponge. We firstly found that the process of sponge retaining TOC and E. coli fitted finely with the following equation: K'?exp (pt) = ln(A1– Ct)– ln(Ct– A2).We design and demonstrated that an integrated system of microalgae and sponge H. perleve can remove 50% inorganic nitrogen and 90% inorganic phosphate in seawater within 48 h.Marine sponge H. perleve is suitable organism to bioremediate and biomonitor coastal aquaculture ecosystem.