Decay of Tenacibaculum maritimum and fecal indicator organisms in sediment‐water microcosms.

WENXIONG LIM ELTON; WUERTZ STEFAN; CHAN SIEW HERNG STAN; CHÁVEZ DÍAZ LUCÍA VALERIA; YUNG PUI YI MARIA

Jornada; Marine Science R&D Program; 2019

As global demand for seafood is increasing, aquatic food production has transitioned from being primarily based on wild capture of fishes to aquaculture. Development of large-scale intensive aquaculture has been associated with a dramatic increase in severe disease outbreaks caused by a diverse range of pathogens. Understanding fate and transport of human and fish pathogens in coastal waters considering microbe-sediments interactions is critical to effectively managing health risk and farming. While the clinical signs and pathogenicity have been well described for many pathogens (Austin 2016; Crane 2011), the contribution of environmental factors to disease formation and reservoirs of these pathogens in the natural environment are poorly understood. The apparent environmental versatility of the Tenacibaculum genus, which includes one of the most important fish pathogens in Singapore, beckons an investigation of its ability to prevail in sediment-based biofilms. On the other hand, it is assumed that any biological agents tend to adhere to or to form macroaggregates. In that sense, it is believed that pathogens attached to such aggregates will persist and remain viable in nearshore environments once they have settled to the sea bottom. The aim of this work was to calculate the decay rates of Tenacibaculum maritimum and fecal indicator organisms in sediment-water microcosm study and to predict the fate and transport of these microorganisms with a view towards safe aquaculture farming practices. Outdoor destroyable microcosm with water and sediment samples from marine farming sites were inoculated with planktonic cells of a known concentration of Tenacibaculum maritimum, Enterococcus faecalis and P22 in treatment 1 and with the same surrogates attached to macroaggregates in treatment 2. Triplicates microcosms were sampled on days 0 3 hs, 0 8 hs, 1, 3, 5, 7, 9, 11, 13 and 15. Cultivation-based methods and qPCR analysis were carried out to analyze the decay in both phases.