Tratamiento físico-químico del agua para el cultivo larvario y el asentamiento de la ostra del Pacífico Crassostrea gigas (Thunberg, 1975)

The Pacific oyster Crassostrea gigas is one of the mollusks with greater production  on  a  global  scale.  The  success  of  its  cultivation  depends  mainly  on  the production of seeds under controlled conditions, for which the quality of water used is a preponderant  factor.  Production  of  C.  gigas  spat  was  evaluated,  both  in  the  larval  and pediveliger  stages,  under  physical  and  chemical  treatments  commonly  used  in  the production  of  invertebrates.  The  different  water  treatments  were  based on  the  filtration and exposure of water to ultraviolet light-UV (1-control treatment) and its variants with the  addition  of  hypochlorite  +  thiosulfate,  hypochlorite  +  vitamin  C,  hypochlorite  + thiosulfate  +  ethylenediaminetetraacetic  acid  -EDTA,  hypochlorite  +  thiosulfate  + vitamin C + EDTA and oxytetracycline antibiotic. The results, expressed in less time of larval  development,  higher  growth  rate  and  size  of  larvae  competent  to  the  settlement, demonstrate the effectiveness of the physical treatment of the filtered water and irradiated with UV in flows of 10 L min-1, and of the therapy based on oxytetracycline to increase the  survival,  as  well  as  positively  influencing  the  settlement  rate.  However,  we  do  not recommend the use of antibiotics in the spat production of C. gigas, because it generated a lower physiological condition of the larvae (2-day delay in larval development) and its effects  on  promoting  resistance  inside  and  outside  the  hatchery.  For  the  production  of postlarvae of C. gigas the use of filtered water up to 1 µm and subsequent exposure to UV rays is recommended, as well as studies searching for alternatives of disinfection or immune strengthening with the use of natural products and probiotics for optimization of larval and postlarval development.