1a.Objectives (from AD-416)
The objectives of this cooperative agreement are as follows:. 1)to develop slow-release non-toxic antifouling additives in coatings in the prevention of biofilm formation on culture tank walls and other components of recirculating aquaculture systems (RAS); and. 2)to develop formulated encapsulations of some of the more active algaecidal compounds included in U.S. Patent #6,949,250 for inhibition of biofilm formation on tank walls and other components of RAS.
1b.Approach (from AD-416)
The accumulation of biofilms on the wetted surfaces of culture tank, vessel, and pipe components in recirculating aquaculture systems (RAS) cause several problems including the following:. 1)requires frequent cleaning to remove unwanted biofilm and help maintain the RAS;. 2)biofilms can serve as a reservoir for harboring or propagating opportunistic fish pathogens; and. 3)compared to RAS-culture water, biofilms contain higher levels of the “earthy” and “musty” off-flavor compounds geosmin and 2-methylisoborneol (MIB) and may also harbor geosmin- and MIB-producing microorganisms. The presence of geosmin and MIB in the flesh of cultured aquatic animals results in an unpalatable product and delays harvest, thereby resulting in large economic losses to the producer. In order to determine if the coatings that contain slow-release non-toxic antifouling additives as provided by ND Life Sciences, Inc., and the encapsulated formulations of algaecidal compounds prevent biofilm formation, replicated strips of coated fiberglass will be suspended in the water of an existing intensive fish culture system located at The Conservation Fund Freshwater Institute, Shepherdstown, West Virginia. After a specific time interval, the fiberglass strips will be removed from the water and microbiological examination and enumeration of biofilm microorganisms will be conducted to evaluate the efficacy of the antifouling technology in preventing biofilm formation. Levels of geosmin and MIB in RAS-culture water and biofilm samples will be determined by instrumental methods [solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS)].
Several types of slow-release antifouling compounds (additives) in coatings underwent efficacy testing to determine the inhibition of biofilm formation on polyvinyl chloride (PVC), a common material used in certain components of recirculating aquaculture systems (RAS). None of the additives that have been tested so far have demonstrated adequate inhibition of biofilm material which can contain significant concentrations of common off-flavor compounds as well as harbor fish pathogenic microorganisms. This research is aligned with the objectives of the discovery of management approaches to mitigate common off-flavors that can occur in fish raised in recirculating aquaculture systems. Monitoring activities used by the ADODR included telephone calls and email.